MINISTRY OF REGIONAL
GOVERNMENT OF ROMANIA
DEVELOPMENT AND TOURISM
www.mdrt.ro
1. ------IND- 2012 0512 RO- EN- ------ 20121002 --- --- PROJET
ORDER
No……….of ………...2012
approving the technical regulation
“Normative document regarding acoustics in structures and urban areas.
Code C 125–2012”
In accordance with the provisions of Article 10 and Article 38(2) of Law No
10/1995 regarding quality in constructions, with its subsequent modifications,
the provisions of Article 2(3) and (4) of the Rules regarding the types of
technical regulations and costs for the regulatory activity in the field of
constructions, town planning, landscaping and habitat, approved by
Government Decision No 203/2003, with its subsequent modifications and
supplementation, and the provisions of Government Decision No 1016/2004
regarding measures for organising and carrying out the exchange of
information in the field of technical standards and regulations, as well as the
rules regarding information society services between Romania and the EU
Member States, as well as the European Commission, with its subsequent
modifications,
on the grounds of Article 5(II)(e) and Article 13(6) of Government Decision
No 1631/2009 concerning the organisation and operation of the Ministry of
Regional Development and Tourism, with its subsequent modifications and
supplementation,
The Ministry of Regional Development and Tourism hereby issues
this
ORDER:
Article 1 - The technical regulation “Normative document regarding
acoustics in structures and urban areas. Code C 125–2012“, is hereby approved
as follows:
a) “Part I – General provisions regarding noise protection. Code C
125/1–2012”, stipulated in Annex 1;
b) “Part II – Design and implementation of sound insulation
measures and acoustic treatments in buildings (revision C125-2005). Code C
125/2–2012”, stipulated in Annex 2;
1
c) “Part III – Noise protection measures in residential, social-cultural
and technical-administrative buildings (revision and supplementation
P122/1989). Code C 125/3–2012”, stipulated in Annex 3;
d) “Part IV – Noise protection measures to be taken in urban areas
(revision GP0001/1996). Code C 125/4-2012”, stipulated in Annex 4.
Article 2 – Annexes 1–4 are an integrated part of the present order.
Article 3 – This order*) shall be published in the Official Journal of
Romania, Part I and shall come into force 30 days after its date of publication .
Article 4 – On the date the present order comes into force, the technical
regulations “Technical instructions for the design of sound insulation measures
for social-cultural and technical-administrative civilian buildings. Code P 1221989”**)) and “Noise protection. Guidelines for the acoustic design and
construction of urban areas. Code GP 0001-96” ***) shall cease to be
applicable, whilst the technical regulation “Normative document for the design
and implementation of sound insulation measures and acoustic treatments in
buildings ( revision C 125-1987). Code C 125-05” ****) shall be repealed.
The technical regulation approved by the present order was adopted in
accordance with the notification procedure No RO/......... of ......................,
stipulated by Directive 98/34/EC of the European Parliament and of the
Council of 22 June 1998, laying down a procedure for the provision of
information in the field of technical standards and regulations, published in the
Official Journal of the European Communities L 204 of 21 July 1998, amended
by Directive 98/48/EC of the European Parliament and of the Council of
20 July 1998, published in the Official Journal of the European Communities L
217 of 5 August 1998.
The Order and its annex shall also be published in the Constructions Journal edited by the “URBANINCERC” National Institute for Research and Development in the field of Constructions, Town Planning and
Sustainable Territorial Development, which is coordinated by the Ministry of Regional Development and
Tourism.
**)
The technical regulation “Technical instructions for the design of sound insulation measures for socialcultural and technical-administrative civilian buildings. Code P 122-1989” was approved by Decision
No 49/1989 of the Central Institute for Building Research, Design and Directives, published in the
Constructions Journal No 3 - 4/1991 edited by the Institute for Research in the field of Constructions –
INCERC Bucharest.
***)
The technical regulation „Noise protection. Guidelines for the acoustic design of urban areas. Code GP
0001-96” was approved by Order No 22/N/03.04.1996 of the Ministry of Public Works and Territorial
Development and was published in the Constructions Journal No 9/1996 edited by the Institute for Building
Research and Construction Economics - INCERC Bucharest.
****)
The technical regulation “Normative document regarding the design and implementation of sound
insulation measures and acoustic treatments in buildings (revision C 125-1987). Code C 125-05” was approved
by Order No 195/15.02.2005 of the Ministry of Transport, Constructions and Tourism and was published in the
Official Gazette Part I, Issue No 460bis/ 31.05.2005 and the Constructions Journal No 15/2005 edited by the
Institute for Building Research and Development and Construction Economics - INCERC Bucharest.
*)
2
MINISTER
Eduard HELLVIG
Annex 2
to Order MDRT No ................../ 2012
NORMATIVE DOCUMENT REGARDING ACOUSTICS IN
STRUCTURES AND URBAN AREAS,
Part II – Design and implementation of sound insulation measures
and acoustic work in buildings (Revision C 125-2005), code C125/22012
3
CONTENTS
1.
1.1.
1.2.
1.3.
GENERAL INFORMATION .................................................................................6
AIM AND FIELD OF APPLICATION .....................................................................6
TECHNICAL REFERENCES ...................................................................................8
TERMINOLOGY .......................................................................................................9
2.
PROTECTION OF FUNCTIONAL UNITS IN BUILDINGS AGAINST
AIRBORNE NOISE .................................................................................................9
PROTECTIVE MEASURES IMPLEMENTED AT THE SOURCE ......................10
PROTECTIVE MEASURES TO BE TAKEN IN THE SOUND RECEIVING
SPACE (ENSURING SOUND ABSORPTION INSIDE FUNCTIONAL
UNITS) .....................................................................................................................16
PROTECTIVE MEASURES APPLIED ALONG THE PROPAGATION
PATHS .....................................................................................................................20
Figure 2.10 ....................................................................................................25
2.1.
2.2.
2.3.
3.
3.1.
3.2.
4.
4.1
4.2
4.3.
4.4
4.5
4.6.
4.7.
PROTECTION OF FUNCTIONAL UNITS IN BUILDINGS AGAINST
IMPACT NOISE ....................................................................................................31
PROTECTIVE MEASURES IMPLEMENTED AT THE SOURCE ......................31
PROTECTIVE MEASURES IMPLEMENTED ALONG THE
PROPAGATION PATHS ........................................................................................32
PROTECTION AGAINST NOISES PRODUCED BY EMBEDDED
INSTALLATIONS AND EQUIPMENT IN BUILDINGS .................................39
VENTILATION AND AIR CONDITIONING SYSTEMS (VAC) ........................39
Figure 4.1.3 Elastic devices for fixing ventilation channels to the ceiling ........ 43
Figure 4.1.8 Rectangular active attenuators with baffles ................................... 46
SANITARY INSTALLATIONS .............................................................................48
HEATING INSTALLATIONS ................................................................................55
ELECTRICAL INSTALLATIONS .........................................................................56
EMBEDDED EQUIPMENT ....................................................................................60
PROTECTION AGAINST STRUCTURAL NOISE PRODUCED BY
INSTALLATIONS ...................................................................................................64
HOUSEHOLD WASTE DISPOSAL SYSTEMS....................................................88
ANNEX 1 RECOMMENDATIONS FOR THE DYNAMIC AND ACOUSTIC
CHARACTERISATION OF EQUIPMENT LOCATED IN INDUSTRIAL
HALLS, AIMED TO ENABLE THE DRAWING UP OF TECHNICAL
DESIGNS ..........................................................................................................89
4
ANNEX 2 SOUNDPROOF CASINGS...............................................................................91
ANNEX 3 METHOD FOR CALCULATING THE ADDITIONAL LEVEL
REDUCTION “ΔLVA” CORRESPONDING TO THE APPLICATION OF
VIBRATION DAMPING TREATMENTS ON THIN BOARDS ....................94
ANNEX 4 DETERMINATION OF THE ATTENUATION INDEX CURVE “RI(F)”
FOR SINGLE AND DOUBLE-LAYERED HOMOGENEOUS CLOSING
ELEMENTS ......................................................................................................96
ANNEX 5 VALUES OF THE AIRBORNE SOUND INSULATION INDEX RW
FOR VARIOUS STRUCTURES OF PARTITION ELEMENTS ..................109
ANNEX 6 GUIDE METHOD FOR CALCULATING THE AIRBORNE SOUND
INSULATION INDEX “RW” FOR SINGLE AND DOUBLE-LAYERED
HOMOGENEOUS CLOSING ELEMENTS ..................................................113
ANNEX 7 ACOUSTIC ABSORPTION COEFFICIENTS (F) FOR CERTAIN
FINISHINGS AND OBJECTS THAT ARE FREQUENTLY USED IN
STRUCTURES (DETERMINED USING THE REVERBERATION
CHAMBER METHOD – SR EN ISO 354) ....................................................117
ANNEX 8 METHOD FOR DETERMINING THE CURVE OF THE SOUND
ABSORPTION COEFFICIENTS “ΑI(F)” FOR VARIOUS SOUNDABSORBING STRUCTURES ........................................................................119
ANNEX 9 VALUES OF THE INSULATION INDEX LN,EQ,O,W FOR REINFORCED
CONCRETE SLABS .......................................................................................125
ANNEX 10 IMPROVEMENT OF THE IMPACT SOUND INSULATION LW FOR
VARIOUS TYPES OF FLOORING ...............................................................126
ANNEX 11 CALCULATION OF THE IMPACT SOUND INSULATION
IMPROVEMENT INDEX, „LW”, FOR A FLOATING SLAB FLOOR ......127
ANNEX 12 ELEMENTS OF ACOUSTIC CALCULATION OF VAC SYSTEMS .........132
5
1. GENERAL INFORMATION
1.1. Aim and field of application
1.1.1. Part II, code C125/2-2012 of this regulation refers to general aspects with regard to
regulating the noise conditions in buildings in order to ensure the permissible acoustic
comfort conditions that are stipulated by law.
The regulation shall be used from the early design stages to adopt acoustic measures
intended to avoid the occurrence of any situations that would be hard to solve during
subsequent design stages.
The regulation also highlights certain priority aspects that need to be dealt with in order to
prevent execution errors that could compromise the good operation of the designed
measures.
Part II of the present normative document is intended for planners, planning assessors,
certified technical experts, contractors, certified technical and operational managers, owners,
administrators and users of urban areas and structures, central and local public
administration authorities, as well as inspection bodies operating in the field.
For the operational application of the regulation, each chapter is organised into three parts:
 general information;
 design elements;
 provisions for carrying out the works.
1.1.2. Noise protection is defined, in accordance with Part I, Code C 125/1-2012, by six
specific technical requirements:
 Protection against airborne noise coming from outside of the building.
 Protection against airborne noise coming from another enclosed space.
 Protection against impact noise.
 Protection against the noise produced by the technical equipment and installations of
a building.
 Protection against excessive reverberated noise and noise produced in the respective
space.
 Environmental protection against noise produced by sources located inside structures
or in relation to them.
These technical requirements are presented in detail in Part I, Code C125/1-2012.
1.1.3. In the spirit of this regulation, the results obtained shall be considered to be optimum
if the acoustic protection measures intended to ensure acoustic comfort are implemented
simultaneously along the entire “noise source – propagation path – sound receiving space
(protected functional unit)” route.
The noise sources taken into consideration in this regulation can act inside or
outside of the protected functional unit. These can be:
 exterior noise sources;
 everyday activities carried out by the users of the building as part of its normal
operation;
 the operation of equipment and installations located inside or outside the building.
1.1.3.1. The acoustic protection measures implemented at the source must lead to
obtaining a minimum emitted acoustic power and a minimum noise level, respectively, in
their immediate vicinity.
6
1.1.3.2. The noise propagation path from the source to the receiving space can be fluid (in
the case of this regulation, it is predominantly airborne). Noises produced at the source
propagate towards the sound receiving space via both paths (airborne noise or structural
noise) or, predominantly, via one of them.
The acoustic protection measures implemented along the propagation paths
imply the installation of inhomogeneity elements (energy dissipation devices) along these
paths.
If the noise is airborne, the inhomogeneous elements are represented primarily by
structural elements with an acoustic impedance much higher than air impedance (e.g. walls,
ceilings).
If the noise is propagated through a solid, the inhomogeneous elements are
represented by gaps in the propagation path, whose acoustic impedance is much lower than
the impedance of the respective path (elasto-damping-dissipative elements).
1.1.3.3. The acoustic protection measures to be implemented in the sound receiving
space (protected functional unit) imply the following:
 a reduction of the emitted acoustic power of interior sources;
 high sound absorption (sound-absorbing treatments).
1.1.4. The technique of protecting functional units against airborne or structural noises
from various sources involves the implementation of certain general measures, whose basic
principles are presented in Chapters 2 and 3 of the regulation. Specific aspects of this issue,
relating to the operation of certain sources that are widely spread in buildings, are presented
in Chapter 4.
7
1.2. Technical references
Standards
Ite Standard
m
No
1
STAS 6156 - 86
2
SR 6161-1: 2008
3
SR 6161-1/C91:2009
4
SR 6161-2: 2008
5
STAS 6161/3- 82
6
SR EN ISO 717-1:2000
7
8
9
10
11
12
13
14
Name
Acoustics in structures. Noise protection in civilian
and social-cultural buildings. Permissible limits and
sound insulation parameters
Acoustics in structures. Part 1: Measurement of the
noise level in civilian structures. Measurement
methods.
Acoustics in structures. Part 1: Measurement of the
noise level in civilian structures. Measurement
methods.
Acoustics in structures. Part 2: Laboratory
determination of the airborne sound insulation for
separating elements that contain doors, windows or
glass elements
Acoustics in structures. Determination of the noise
level in towns and cities. Determination method.
Acoustics. Rating of sound insulation in buildings
and building elements. Part 1: Airborne sound
insulation.
SR EN ISO 717-1:2000/ Acoustics. Rating of sound insulation in buildings
A1:2007
and building elements. Part 1: Airborne sound
insulation. Amendment 1: Rounding up rules for
assessing unique values and quantities expressed by a
unique value.
SR EN ISO 717-2: 2001
Acoustics. Rating of sound insulation in buildings
and building elements. Part 2: Impact sound
insulation.
SR EN ISO 717-2:2001/ Acoustics. Rating of sound insulation in buildings
A1:2007
and building elements. Part 2: Impact sound
insulation. Amendment 1
SR
EN
ISO
717- Acoustics. Rating of sound insulation in buildings
2:2001/C91:2007
and building elements.
Part 2: Impact sound insulation.
SR EN ISO 10140-2: 2011
Acoustics. Laboratory measurement of the sound
insulation of structural elements. Part 2:
Measurement of airborne sound insulation
SR EN ISO 10140-3:2011
Acoustics. Laboratory measurement of the sound
insulation of structural elements. Part 3:
Measurement of impact sound insulation
SR EN ISO 140-4: 2002
Acoustics. Measurement of sound insulation in
buildings and building elements. Part 4: In situ
measurement of airborne sound insulation between
rooms
SR EN ISO 140-7: 2002
Acoustics. Measurement of sound insulation in
buildings and building elements. Part 7: In situ
8
15
STAS 7150 - 77
16 STAS 12203/1- 83
17 STAS 12025/1- 81
18 SR 12025-2: 1994
19 SR ISO 2631-1: 2001
20 STAS 8048/1- 91
21 SR EN ISO 354: 2004
22 STAS 1957/1-88
23 STAS 1957/3-88
measurement of impact sound insulation of ceilings
Acoustics in industry. Methods for measuring the
industrial noise level
Acoustics in structures. Determination of the acoustic
power level in anechoic and semi-anechoic rooms.
Determination method
Acoustics in structures. The effects of vibrations
produced by road traffic on buildings or parts of
buildings. Measurement methods
Acoustics in structures. The effects of vibrations on
buildings or parts of buildings. Permissible limits
Mechanical shocks and vibrations. Assessment of
human exposure to overall body vibrations. Part 1:
General requirements
Acoustics in structures. Mechanical vibration
isolation products. Determination of elastic quality
under dynamic actions
Acoustics. Measurement of sound absorption in a
reverberation room
Acoustics. Terminology. Physical acoustics
Acoustics. Terminology. Acoustics in constructions
and transport
Note:
1. The dated references were taken into account on creation of the technical regulation;
2. On the date of use of the technical regulation, the latest edition of the standards and all
applicable amendments thereto shall be consulted.
1.3. Terminology
The terminology used in this regulation is in line with the following:
STAS 1957/1-88 Acoustics. Terminology. Physical acoustics.
STAS 1957/3-88 Acoustics. Terminology. Acoustics in constructions and transport.
2. PROTECTION OF FUNCTIONAL UNITS IN BUILDINGS
AGAINST AIRBORNE NOISE
Functional units in buildings shall be protected against noise coming from sources
operating outside or inside them.
In both situations, the protection shall be provided by implementing:
- protective measures at the source (which lead to a reduction of the noise
emitted by the sources), in accordance with paragraph 2.1.
- protective measures in the sound receiving space (which ensure acoustic
absorption inside the functional unit), in accordance with paragraph 2.2.
For noise coming from sources operating outside of the functional unit, the following
must also be implemented:
- protective measures along the propagation paths (ensuring protection of
the functional units through their closing elements or partitions) in
accordance with paragraph 2.3.
9
2.1. Protective measures implemented at the source
2.1.1. The noise sources taken into consideration in this regulation can act inside of the
protected functional unit or outside of the building. These can consist of:
- everyday activities carried out by the users of the building as part of its normal
operation;
- the operation of equipment and installations located inside and outside the
building;
- the operation of machinery and/or means of transport in traffic.
2.1.2. The characteristic noise levels for the operation of the main equipment and
machinery in residential and social-cultural buildings, as well as for carrying out their
specific activities, are given in Part III, Code C125/3-2012.
2.1.3. Airborne noise produced by sources located inside or outside of the protected
functional unit shall be reduced by:
- selecting the correct sources and regulating their use, in accordance with
paragraph a.
- using local acoustic protection systems, in accordance with paragraph b
(soundproof casings and acoustic protection screens).
a. Selecting the correct sources and regulating their use
2.1.4. The purpose of selecting the correct sources and regulating their use is:
- to reduce the noise level produced by the sources;
- to reduce the significant nature of the noise produced by the sources.
2.1.4.1. The noise level emitted by the sources shall be reduced by adopting, as early as
the technological design stage, the most quiet equipment possible, which is potentially
equipped with acoustic protection accessories provided by the manufacturer or designed at a
later date, in accordance with paragraph b of this chapter.
For industrial buildings which house many heavy machinery and equipment, the
technical designs must include an acoustic calculation spreadsheet for the industrial facility,
in accordance with the provisions of the technical regulation on the design and
implementation of noise and anti-vibration protection measures in industrial buildings, in
order to highlight those situations in which the permissible noise limits stipulated by the
technical regulations in force can be exceeded. This spreadsheet shall be prepared on the
basis of the data contained by the internal rules or the specifications of the machinery and
equipment, drawn up in accordance with the “Recommendations for the dynamic and
acoustic characterisation of machinery in industrial halls” (ANNEX 1).
2.1.4.2. The significant nature of noise in civilian buildings shall be reduced by adopting
real source utilisation programmes, so that they operate during periods of time in which their
informational contribution is minimum (regardless of whether the noise they produce is
masked by noises of great utility for the respective building, or it only occurs during those
periods of time in which the users of the building do not perceive it).
For industrial buildings, the significant nature of the noise shall be reduced in
accordance with the provisions stipulated in the technical regulation on the design and
implementation of noise and anti-vibration protection measures in industrial buildings with
regard to classifying various types of industrial halls into classes of acoustic efficiency.
b. Soundproof casings
10
2.1.5. Soundproof casings are spatial structural elements designed to attenuate the
transmission of noises produced by a source to the environment by completely covering the
source.
The casing also ensures:
- prevention of potential accidents that could occur due to direct contact with the
equipment;
- ventilation of the machines, etc.
The design of the casings and their classification depending on their structure, their
compliance with certain technological requirements, their accessibility, etc. are presented in
ANNEX 2.
2.1.6. The casings can be located, in relation to the sources, in one of the following ways:
- outside of the limits of the acoustic near field corresponding to the source;
- within the limits of the acoustic near field corresponding to the source.
2.1.7. The acoustic near field of a source shall be determined in accordance with Figure
2.1.
Design elements
2.1.8. For a point located outside of the casing, the noise level reduction as a function of the
frequency,  Lc  f  , by complete encasing, shall be given by relationship:
 Lc  f   L1  f   L 2  f
where:

(dB)
(2.1.)
L1  f  - the noise level in the given point in the absence of the casing, in dB;
L2  f  - the noise level in the given point after encasing, in dB.
The value  Lc  f  can be obtained by:
- acoustic measurements, whether they are carried out in situ or in a
laboratory (using models);
- calculation.
The usable frequency range that must be taken into consideration shall depend on
the spectral characteristics of the source being encased.
2.1.9. The reference standard for determining the value “  Lc  f  ” for in situ acoustic
measurements is STAS 7150, whilst the standard for laboratory acoustic measurements is
STAS 12203/1.
2.1.10. The value “  Lc  f  ” for casings made of panels with an identical structure can
be calculated, for guidance, using the relationship:
Lc  f   R f   10 lg
where:
S
Ai  f 
(dB)
(2.2.)
R f  - acoustic attenuation index corresponding to the structure of the casing
panels, in dB;
S - total area of the casing underside, in m2;
Ai  f  - equivalent sound absorption area of the casing underside, in m2.
Relationship (2.2.) shall be valid for situations in which:
11
- the casing is located outside of the limits of the acoustic near field corresponding
to the source;
- the casing is located within the limits of the acoustic near field corresponding to
the source, but has an intense sound-absorbing treatment applied to its underside, which has
the sound absorption coefficients  i  f   0,80 for the entire usable frequency range.
Note:
Relationship (2.2.) cannot be used for casings located within the limits
of the acoustic near field corresponding to the source, which have
sound-absorbing treatments applied to their underside and are
characterised by the sound absorption coefficients  i  f   0,80 . In this
situation, acoustic measurements must be carried out in accordance
with point 2.1.9.
2.1.10.1. The acoustic attenuation index “ R f  ” can be determined by:
- the reference standard for in situ or laboratory acoustic measurements is SR
6161-2;
- calculation, in accordance with the provisions of sub-chapter 2.3.1 and Annex 4.
2.1.10.2. The equivalent sound absorption area of the casing underside shall be calculated
with relationship:
A (f) =  i Si
where:
(m2 A.U.)
(2.3.)
i
- sound absorption coefficient of the treatment “i”; [-]
Si
- geometric surface on which the treatment “i” is applied; [m2]
2.1.11. For casings made of panels of different structures, the value “  Lc  f  ” shall be
determined by calculation using relationship (2.2.), where R f  is the lowest value of the
acoustic attenuation indices corresponding to various types of panels.
2.1.12. If efficient vibration damping treatments (with the internal damping coefficients
  102 ) are applied to the surface of a casing, the additional level reduction  L va  f  shall
be added to the value “  Lc  f  ” calculated with relationship (2.2) . The technical regulation
on the design and implementation of noise and anti-vibration protection measures in
industrial buildings shall be referred to when choosing the material and its corresponding
coefficient  .
The efficient vibration damping treatments taken into consideration in this case
consist of thin plastic boards, metal sheets, etc. applied to the casing using layers of products
with low dynamic stiffness (e.g. felt, spongy polyurethane, etc.).
The value  L va  f  can be determined by:
- acoustic measurements performed in a laboratory;
- calculation, in accordance with ANNEX 3.
2.1.13. When a casing must be provided with openings for ventilating or monitoring the
sources, the design stage shall be carried out as applicable, with the contribution of
specialists in the field.
2.1.14. If the casings are made of flammable products or are installed for equipment
operating at high temperatures, they shall be designed in accordance with the provisions
stipulated in the regulations on fire safety in constructions.
12
Provisions for carrying out the works
2.1.15. When installing soundproof casings, special care shall be taken to assemble the
constituent panels correctly, so that the resulting casings care as soundproof as possible.
2.1.16. For soundproof casings located within the acoustic near field of a source, the casing
shall be positioned as accurately as possible to prevent the possibility of any rigid contact
between the casing and the source.
2.1.17. The sound-absorbing treatment (on the casing underside) and the vibration damping
treatment (on the exterior surface) shall be applied so that they cannot come off, gradually,
during operation of the casing.
2.1.18. The products and design solutions stipulated in the technical documentation can
only be changed with the approval of the design engineer.
c. Noise protection screens (installed at the source)
2.1.19. Noise protection screens (installed at the source) are planar or spatial structures
made of panels or other structural elements which partially mask the noise source from the
sound receiving points taken into consideration, and are located within the acoustic near
field of the source (defined in Figure 2.1.).
Vertical section
Plane
Figure 2.1 – Determination of the limits of the acoustic near field corresponding to a
noise source
A – is the approximate parallelepiped of the real equipment, with the dimensions L, l,
h;
B – is the approximate hemisphere of the acoustic near field limit, characterised by
“r”
13
r = max. (L; 2h)
where:
L = the largest dimension of the base rectangle;
h = height of the approximate parallelepiped of the real equipment.
2.1.20. Noise protection screens can be made of:
- opaque elements (metallic plates, wood products, fired clay or reinforced
concrete masonry, etc.);
- transparent elements (glass sheets or glass bricks, polycarbonate, plexiglass, etc.)
used when permanent visual monitoring of the source is required.
Design elements
2.1.21. The minimum dimension “l” of a noise protection screen must comply with the
relationship:
l
340
f0
(m)
(2.4.)
where:
f 0 , in Hz, is the lowest frequency of the range within which the screen must reduce
the noise produced by the source.
2.1.22. The efficacy of the noise protection screens shall manifest in the acoustic shadow
areas they create. The acoustic shadow area can be determined graphically by drawing radii
from the geometric centre “O” of the base rectangle of the parallelepiped that approximates
the real equipment (see Figure 2.1.) to the contour of the screen.
2.1.23. The value “  Les  f  ” by which the noise level is reduced at a point within the
acoustic shadow area (Figure 2.2.), due to the presence of a noise protection screen, can be
determined by:
- acoustic measurements performed in situ;
- calculation.
14
VERTICAL SECTION
ACOUSTIC
SHADOW AREA
PLANE
REDUCED ACOUSTIC
SHADOW AREA
Figure 2.2 – Areas of acoustic shadow behind the screen
The noise level reduction “  Les  f  ” shall be obtained by in situ measurements, in
0
accordance with the reference standard STAS 7150, by determining the noise level “ Ls  f  ”
at a point in the absence of the screen, “ Ls  f  ” at the same point after the screen is
installed, and by applying the relationship:
Les  f   L0s  f   Ls  f  (dB)
(2.5.)
The noise level reduction “  Les  f  “, expressed in percentages of the acoustic
attenuation index R f  corresponding to the screen structure, shall be obtained by
h
calculation using the diagram shown in Figure 2.3. as a function of the ratio  , where:
h - height of the screen above the plane which contains the characteristic noise emittingreceiving points;
c
 - wavelength, in metres,   ;
f
c - speed of sound propagation through air (340 m/s);
f - sound frequency, in Hz.
15
Figure 2.3 – Reduction of the noise level Les (% R) by installing a screen in the near
field of a source
With the following known elements:
- noise spectrum of the emitting source;
- noise level permissible in the sound receiving area,
the diagram shown in Figure 2.3. can be used to determine:

either h, the design height of the screen above the plane which
contains points E, M (see Figure 2.2.);

or the structure of the screen to which a certain diagram R f  of the
attenuation index is associated.
Note: The attenuation index R(f), corresponding to the structure of the screen, shall
be determined by:
- in situ or laboratory acoustic measurements in accordance with the reference
standard SR 6161/2;
- calculation, in accordance with paragraph 2.3.1 and ANNEX 4.
2.1.24. If using flammable products to make noise protection screens, or when screening
equipment which operates at high temperatures, the soundproof screens shall be designed in
accordance with the provisions stipulated in point 2.1.14.
Provisions for carrying out the works
2.1.25. When installing noise protection screens consisting of two or more panels, special
care shall be taken to ensure that the panels are correctly assembled so that the joints
between them are as airtight as possible.
2.1.26. The chosen position of the noise protection screens with respect to the source shall
eliminate the possibility of any rigid contacts occurring between the screens and the source.
2.1.27. Other building products than those stipulated in the technical documentation can only
be used with the approval of the design engineer.
2.2. Protective measures to be taken in the sound receiving space (ensuring sound
absorption inside functional units)
2.2.1. Airborne noise inside a sound receiving space can be reduced by sound absorption, by
equipping the respective space with surfaces or objects that can dissipate most of the acoustic
16
energy of the incident waves. These surfaces or objects are called sound-absorbing
treatments.
2.2.2. The noise level reduction due to applying sound-absorbing treatments inside the sound
receiving space, “Δ LA”, can be determined by:
- acoustic measurements performed in situ;
- calculation.
2.2.3. The noise level reduction, Δ LA, following the application of sound-absorbing
treatments inside the sound receiving space can be determined by calculation, as follows:
a) for rooms in which an acoustic diffuse field is obtained (where the noise comes from
sources located outside of the room or, for rooms characterised by a uniform noise level
produced by speaking or relatively small noise sources - typewriters, fans, vacuum cleaners,
etc. that can be inscribed in spheres with a radius of less than 50 cm), the noise level reduction
can be calculated with the relationship:
A2 ( f )
Δ LA(f)= 10 lg A1 ( f )
(dB)
(2.6.)
where:
A1 ( f ) - the equivalent sound absorption area corresponding to a room that is not
subject to acoustic treatment (m2 A.U.)
A2 ( f ) – equivalent sound absorption area corresponding to a room with soundabsorbing treatments, (m2 A.U.)
b) for rooms containing a single noise source of large dimensions, the reduction “Δ LA”
shall be determined as a function of the distance between the source and the equivalent
absorption area of the room, using the diagram shown in Figure 2.3.
c) for large rooms containing many noise sources of relatively large dimensions, the
noise level reduction can be calculated using the calculation methodology stipulated in the
technical regulation on the design and implementation of noise and anti-vibration protection
measures in industrial buildings.
The main types of sound-absorbing treatments that are frequently used are:
a)
Plates (mats) made of porous materials (with open porosity) and structures
constructed based on these;
b)
Vibrating membranes;
c)
Mixed sound-absorbing structures (made of porous plates and vibrating membranes);
d)
Sound-absorbing resonance structures.
2.2.4. The coefficient “  i  f  ” corresponding to the surface “Si” shall be determined by:
- acoustic measurements performed in a laboratory;
- calculation.
2.2.4.1.
The reference standard for determining the coefficient “  i  f  ” by laboratory
acoustic measurements is SR EN ISO 354 .
ANNEX 7 of this regulation presents the values of the sound absorption coefficient “
  f  ” for the main finishings or surfaces that are traditionally used in constructions,
determined by acoustic measurements carried out in a laboratory.
17
The technical regulation on the acoustic design and execution of public audition halls
stipulates the values of the sound absorption coefficient “   f  ” for various sound-absorbing
treatments that are frequently used in social-cultural buildings and industrial halls.
2.2.4.2.
The sound absorption coefficient “  i  f  ” can be approximated, by calculation,
in accordance with ANNEX 8.
2.2.5. The sound receiving space can contain:
- furniture or ornamental items (without any special sound-absorbing properties);
- special sound-absorbing structures (for example, pyramid-shaped sound-absorbing
objects - Figure 2.13.).
2.2.6. The equivalent sound absorption area “Ak(f)” corresponding to an object located inside
the sound receiving space shall be determined by laboratory acoustic measurements, in
accordance with the provisions of SR EN ISO 354.
ANNEX 8 of this regulation specifies the values of the equivalent sound absorption
area “Ak(f)” for a few representative objects in buildings.
Design elements
2.2.7. Plates (mats) made of porous materials (with open porosity) can be installed directly
on the building elements or away from them.
Sound-absorbing plates (mats) with a low thickness (3–5 cm) shall be installed
directly onto a structural element, especially when the support is continuous and flat and
their acoustic properties (more reduced within the low and medium frequency ranges) meet
the necessary requirements. They can be installed onto a continuous support by gluing or
using mechanical retaining devices.
Sound-absorbing plates (mats) are installed away from the structural element:
- for acoustic purposes, when aiming to ensure increased efficacy within the low
and medium frequency ranges;
- for thermo-technical purposes, when special measures need to be implemented
in order to avoid condensation on the exterior walls, ceilings located on the top storey, etc.
- for structural purposes, to cover surfaces that display many uneven areas or to
install suspended ceilings that have an aesthetic function.
Details about the installation of such structures are given in the technical regulation on the
acoustic design and execution of public audition halls.
2.2.8. Vibrating membranes shall be installed in the following situations:
- to ensure a high level of sound absorption in rooms containing noise sources which emit
mainly in a narrow frequency band;
- to enlarge the maximum acoustic efficiency range of the treatments applied in a room,
especially within the low frequency range.
2.2.9. Sets of sound-absorbing objects shall be used in rooms which require a very high
level of sound absorption within the entire frequency range (100–4 000 Hz), such as: radio
and television studios, anechoic rooms, audiometric testing rooms, etc.
Details about the structure and installation of such sound-absorbing treatments are given in
the technical regulation on the acoustic design and execution of public audition halls.
18
2.2.10. The acoustic design of sound-absorbing treatments shall take into consideration the
provisions stipulated in the technical regulations on fire safety in constructions.
Proposals for carrying out the works
2.2.11. Sound-absorbing plates can be installed directly on the surface of a structural
element by:
- gluing;
- mechanical retaining devices.
If installed by gluing, the installation technique shall consist of the following stages:
a) preparation and inspection of the supporting surface;
b) drawing;
c) gluing the plates;
d) finishing the joints and correcting the visible faces.
a) During preparation and inspection of the supporting surface, its smoothness shall be
checked using a 1.00 m level, only one 2 mm burr being permitted at 1.00 m. Before
installation, the supporting surface shall be cleaned of any impurities. The relative humidity
of the support must not exceed 5 %. If the sound-insulating plates are installed in rooms in
existing buildings, on painted walls, the layer of paint shall be removed off the walls before
their installations. Sound-absorbing plates can be installed directly onto oil-painted surfaces
after these surfaces have been cleaned of any impurities;
b) Plotting shall be carried out from the centre of the surface towards its edges, so that any
execution defects can be resolved by adjusting the dimensions or joints;
c) Sound-absorbing plates shall be glued onto the supporting surface in accordance with the
technique recommended by the manufacturer of the adhesive being used;
d) For factory-finished sound-absorbing plates, only those plates whose visible face is not
damaged shall be installed. After installation, any slight damage to the plates (that may
occur during execution) shall be corrected by applying filler or water-based paint.
A finishing layer shall be applied to sound-absorbing plates that are not factory-finished, on
the basis of aesthetic and mechanical protection criteria; this finishing layer shall meet the
following main requirements:
- to prevent spreading particles of sound-absorbing material into the environment;
- to preserve the initial sound-absorbing properties (for this reason, the finishing element
must have the lowest specific airflow resistance possible).
If the plates are installed by means of mechanical retaining devices, they shall be applied in
accordance with the provisions of the technical design, which must stipulate:
- the position of the connecting pieces that are left in the supporting element;
- details about the supporting elements for the sound-absorbing plates.
2.2.12. Sound-absorbing plates provided with a gap shall be installed using a supporting
frame. The supporting frame can be made primarily of fireproof timber or metallic elements.
Its application shall be carried out in accordance with the provisions of the technical design,
which must stipulate:
- the position of the connecting pieces that are left in the supporting element;
- details about the connecting elements between the support and the sound-absorbing
plates;
- details about the supporting elements for the sound-absorbing plates.
The planar dimensions of the supporting frame for the sound-absorbing treatments shall be
chosen in accordance with the provisions of the regulations on fire safety in constructions,
with regard to the measure of partitioning (breaking the continuity of) the gaps between the
treatments and the supporting surface.
19
2.3. Protective measures applied along the propagation paths
(reducing the noise level depending on the distance between the source and the sound
insulation of the functional units)
2.3.1. The protective measures adopted along the airborne noise propagation paths must
comply with the following requirement:
 Lef ( f )   Lnec ( f )
(dB)
(2.7.)
where:
 L nec ( f )  L s ( f )  L adm ( f )
(dB)
(2.7’.)
where:
Ladm - permissible noise level, depending on the type of activities carried out in the
protected functional units, stipulated in Part III, code C 125/3-2012; Ladm can be expressed
by a noise curve (Cz) or an overall noise level, in dB(A);
Ls(f) - noise level at the limit of the acoustic near field (as shown in Figure 2.1):
4r 2
Ls ( f )  LPS ( f )  10 lg 2
ro
(dB)
(2.8)
where:
LPS - acoustic power level of the source, (dB);
r - radius of the approximate hemisphere of the acoustic near field, (m);
ro - the 1 m distance measured from the centre of the source, which is used to
measure LPS.
 Lef ( f ) is the actual noise level reduction obtained along the propagation paths
depending on the distance between the source and the sound receiving space, as well as the
sound insulation measures adopted.
Applying sound insulation measures along the propagation paths means to install
obstacles with an acoustic impedance higher than the acoustic impedance of the propagation
medium (air) on these paths.
These obstacles are structural elements which can ensure:
 full closure of the propagation paths (homogeneous and non-homogeneous walls — with
doors and windows, homogeneous and non-homogeneous floors — with hatches, etc.)
 partial closure of the propagation paths (partial walls or floors).
The reduction “  Lef ( f ) ” can be determined by:
 the reference standards for acoustic measurements carried out in situ, which are SR
6161-1, SR 6161-1/C91, STAS 6161/3 and STAS 7150, and standard STAS 12203/1 for
laboratory measurements.
 calculation, in accordance with the provisions stipulated in paragraphs 2.3.2 - 2.3.3.
The usable frequency range to be taken into consideration shall depend on the spectral
characteristics of the source.
2.3.2. If no sound insulation measures have been implemented along the noise
propagation paths from the source to the sound receiving space, the reduction “  Lef ( f ) ”
can be determined by calculation, as follows:
20


For an acoustic diffuse field (characterised mainly by noise level uniformity in each
point within the space) Lef ( f )  0 , regardless of the type of source taken into
consideration.
For an acoustic free field (in which the sound emitted by the source is propagated
without affecting the surface of the delimiting elements of the space)
 Lef ( f )  k lg
r1
r
(dB)
(2.9)
where:
Noise level reduction (dB)
r1 - distance from the source to a point within the sound receiving space, (m);
r - radius of the approximate hemisphere of the acoustic near field (as shown in
Figure 2.1), (m);
k - source directivity characteristic, with the following values:
k = 0, for plane waves;
k = 10, for cylindrical waves;
k = 20, for spherical waves.
 For an acoustic intermediate field (whose characteristics are between those of the
diffuse field and those of the free field), the value for the variable “  Lef ( f ) ” shall be
determined in accordance with the diagram shown in Figure 2.4.

Figure 2.4
Distance from the centre O of the source (as
shown in Figure 2.1)
Attenuation of the source noise level depending on the distance and
equivalent absorption area of the room
2.3.3. If structural elements are installed along the noise propagation paths from the
source to the sound receiving space, within a (total or partial) closing plane, the reduction “
 Lef ( f ) ” can be determined by calculation, as follows:
2.3.3.1.
When using elements that ensure full closure of the propagation paths, the
reduction “  Lef ( f ) ” shall be calculated depending on the nature of the acoustic fields, as
follows:
21
a) For propagation from an acoustic diffuse field to another acoustic diffuse field
(Figure 2.5), a situation which occurs during the transmission of noise between small
rooms (volume of less than 100 m3) without an acoustic treatment, located in
residential and social-cultural buildings,
Lef ( f )  R( f )  10 lg
S
A( f )
(dB)
(2.10)
where:
R(f) - acoustic attenuation index for the element ensuring the full closure of the
propagation path, in dB;
S - area of the element ensuring the full closure of the propagation path, in m2;
A(f) - equivalent sound absorption area corresponding to the sound receiving space,
in m2.
element ensuring the complete
closure of the propagation path
Figure 2.5.
b) For propagation from an acoustic diffuse field to an acoustic free field (Figure
2.6), a situation which occurs during the transmission of noise from inside rooms
without acoustic treatment to the outside, or from inside industrial halls without
acoustic treatment and many noise sources of similar acoustic power to the outside
(Figure 2.5)
element ensuring the complete
closure of the propagation path
Figure 2.6.
b1) for r  0,4 S
Lef ( f )  R ( f )  6
(dB)
(2.11)
where:
r - distance between the element ensuring full closure of the propagation path to the
sound receiving point, in m;
S - area of the element ensuring the full closure of the propagation path, in m;
22
R(f) - acoustic attenuation index corresponding to the element ensuring the full
closure of the propagation path, corrected as a function of the indirect transmissions
via the connections to the adjacent elements, in dB.
b2) for 0,4 S  r  1,5 S , the reduction “ Lef ( f ) ” at a point M(r,θ,φ) in accordance
with Figure 2.7, shall be calculated by linear interpolation between the values obtained at
points b1 and b3.
Figure 2.7.
b3) for r  1,5 S , the reduction “ Lef ( f ) ” at a point M(r θ,φ) in accordance with
Figure 2.7, shall be calculated with the relationship:
Lef ( f )  R( f )  10 lg
4S (r )
  H ,
S
(dB)
(2.12)
where:
r, S, R(f) have the meaning specified in point b1;
Sα(r) - area of the spherical cone with the radius “r” limited by the solid angle at the
centre “θ”, which represents the wavefront from the source, in m2;
 H - the deviation from the uniform emission in a free space, in dB, in accordance
with the provisions of the technical regulation on the design and implementation of
noise and anti-vibration protection measures in industrial buildings.
c) For propagation from an acoustic free field to an acoustic diffuse field, a situation
which occurs during the transmission of noise from outside of the building to rooms
without acoustic treatment (Figure 2.8),
element ensuring the complete
closure of the propagation path
Figure 2.8.
23
Lef ( f )  k lg
r1
4S cos 
 R( f )  10 lg
,
r
A( f )
(dB)
(2.13)
where:
R(f), S, A(f) have the meaning given in relationship (2.10);
k, r1, r have the meaning given in relationship (2.9);
β - angle of incidence of the sound with the plane of the structural element taken into
consideration.
d) For propagation from an acoustic intermediate field to another acoustic
intermediate field, a situation which occurs during transmission between rooms
with acoustic treatment (Figure 2.9),
Lef ( f )  L1 ( f , r1 )  R ( f )  10 lg
S
 L2 ( f , r2 )
A2 ( f )
(dB)
(2.14)
where:
R(f), S, A2(f) have the meaning given in relationship (2.10);
L1 ( f , r1 ) si L2 ( f , r2 ) - noise level reductions determined using the diagram
shown in Figure 2.4, (dB).
Figure 2.9.
Note:
If the structural element ensuring the full closure of the
propagation paths has a non-homogeneous structure (with distinct sound
attenuation areas), the calculations stipulated in relationships (2.10) (2.14) shall be carried out for each of its components. The value „
Lef ( f ) “, taken into consideration shall be, at a random point of the
sound receiving space, the lowest of the resulting values.
2.3.3.2.
When using structural elements that ensure partial closure of the
propagation paths, the reduction “  Lef ( f ) ” shall be calculated depending on the nature of
the acoustic fields, as follows:
a) During propagation from an acoustic diffuse field to another acoustic diffuse field
(Figure 2.10),
 A ( f )  S no 
Lef ( f )  10 lg  0,21R ( f )

S ip  S no 
10
(dB)
(2.15)
where:
Sip - area of the element ensuring the partial closure of the propagation path, in m2;
Sno - non-blocked area within the plane of the element ensuring partial closure, in m2;
R(f) – acoustic attenuation index corresponding to the element ensuring partial
closure, in (dB);
24
A2(f) - equivalent sound absorption area in the protected space, (CR), calculated
without taking into consideration the non-blocked area, in m2.
compulsory sound-absorbing area
section AA
Figure 2.10
For elements ensuring the partial closure of the propagation paths with the indices
R( f )  15dB , the reduction “  Lef ( f ) ” can be determined using the diagram shown in
Figure 2.11.
Figure 2.11. The reduction L due to installing a
partial closing element within an acoustic diffuse field.
b) During propagation from an acoustic free field to another acoustic free field, for
screen-type partial closing elements with practically infinite length (Figure 2.12) and
attenuation indices R( f )  15dB , the reduction “  Lef ( f ) ” can be determined using the
diagram shown in Figure 2.13.
25
reception
emission
Figure 2.12
Figure 2.13
Diagram for determining the noise level reduction by means
of screens with practically infinite length.
Note:
The wavelength “λ” corresponding to the frequency f =
500 Hz shall be taken into consideration when calculating the overall noise
level, in dB(A).
2.3.4 The acoustic attenuation index “R(f)” can be determined by:
- acoustic measurements carried out in situ or in a laboratory in accordance with
the provisions of SR EN ISO 140-4, SR EN ISO 10140-2;
Note:
The acoustic attenuation index determined in laboratory
conditions, where the noise transmission through the elements
adjacent to the element being tested (collateral paths) is
practically zero, shall have the notation “R(f)”.
For in situ measurements, in which the noise transmission through
the adjacent elements becomes measurable, the acoustic
attenuation index shall have the notation “R'(f)”. Its value shall be
different from the variable R(f) depending on the nature of the
collateral paths, which must be detailed in the measurement
report;
26
- calculation, in accordance with the provisions stipulated in paragraphs 2.3.6–
2.3.11 of this regulation.
2.3.5 The equivalent absorption area “A(f)” shall be determined using relationship 2.3.
2.3.5.1.
For residential and social-cultural buildings, requirement (2.7) shall be
expressed with the relationship:
RW,ef ≥ RW,nec
(dB)
(2.16)
where:
RW,ef
-
RW,nec
-
the actual airborne sound insulation index for the structural element
(calculated in accordance with the reference standard SR EN ISO 7171, SR EN ISO 717-1/A1, using the “R(f)” values determined in
accordance with the reference standard SR EN ISO 10140-2 Acoustics.
Laboratory measurement of the sound insulation of structural elements.
Part 2: Measurement of airborne sound insulation
the airborne sound insulation index necessary for the structural element,
stipulated in Part III, Code C 125/3-2012
Determination of the acoustic attenuation index “R(f)” by calculation
2.3.6 The acoustic attenuation index “R(f)” is defined by the relationship:
R(f) = 10lg Pi / Pr (dB)
(2.17)
where:
- Pi - the incident power on the surface of the propagation path closing element (W);
- Pr - the power emitted by the propagation path closing element (W).
The “R(f)” index is represented in the form of a curve with values for each 1/3
octave within the usable frequency range (for residential and social-cultural buildings: 100 –
3 150 Hz).
2.3.7 Essentially, the values of the “R(f)” index depend on the structural type of the
closing element taken into consideration. In accordance with this regulation, the following
categories of structures shall be taken into consideration:
a) homogeneous and non-homogeneous (within the plane of the closing element
taken into consideration);
b) single-layered and multi-layered (double, sandwich-type and casing-type).
2.3.8 For single-layered, homogeneous closing elements, the “R(f)” index can be
determined by calculation, in accordance with the methodology presented in ANNEX 4.
2.3.9 For double, homogeneous closing elements, the “R(f)” index can be determined by
calculation, in accordance with the methodology presented in ANNEX 4.
2.3.10 For compound single-layered or multi-layered closing elements, the index “ R f  ”
can be determined using the diagram shown in Figure 2.14.
27
2.3.11 The actual airborne sound insulation index, RW,ef, shall be determined by comparing
the “R'(f)” curve corresponding to a closing element (determined by acoustic measurements
or calculation, by taking into account the propagation via collateral paths) to a standard
curve, in accordance with the methodology presented in SR EN ISO 717-1, SR EN ISO 7171/A1.
ANNEX 5 of this regulation presents a few constructive structures that are frequently
used for closing elements, whose airborne sound insulation indices RW are determined by
means of acoustic measurements.
For guidance, the in situ airborne sound insulation index RW for single-layered or
multi-layered homogeneous closing elements can be determined in accordance with
ANNEX 6.
Note: Solutions providing closure elements for airborne noise propagation
paths, calculated in accordance with ANNEX 6, shall only be included in
designs after they have been verified by means of laboratory
measurements in accordance with SR EN ISO 10140-2.
28
Figure 2.14 – Determination of the attenuation index R f of the compound structure
R0 – attenuation index of the solid wall
Ri – attenuation index of the door or window
R - attenuation index of the compound wall
S – wall surface, including the door or window
S1 – surface of the door or window
Design elements
2.3.12 The structural element for ensuring closure of the noise propagation paths shall be
chosen depending on the entire set of requirements that it must meet in a building.
29
In principle, the interior walls and floors which are part of the supporting structure of the
buildings are, from an acoustic point of view, designed to act as single-layered elements.
The requirements for providing sound insulation between functional units separated by such
a structural element can be met either directly by the structure resulting from the safety
criteria, or by supplementing the structure in an appropriate manner. The necessary
supplementation can be provided as follows:
- over-sizing the single-layered element (which is often the case with the floors in
residential buildings);
- adding a structural element located at a certain distance from the supporting
element.
In the second situation, the added element must also meet all the corresponding
requirements, except for those that fully apply to the supporting element.
The position of the added element with respect to the supporting element should,
overall, create a double structure.
The main requirements for the structure of interior walls, which only act as
partitions, are those regarding: sound insulation, fire resistance and the aesthetic appearance
of the element.
Under these conditions, the best aesthetic results shall be obtained when double
structures are used. However, the most favourable response to the set of requirements is
provided by a casing-type structure, dimensioned from the point of view of its behaviour to
noise action so that its sound insulation capacity is as similar as possible to the capacity of a
double structure with comparable physico-mechanical parameters.
2.3.13 The acoustic design of closing elements for airborne noise propagation paths shall
take into consideration the provisions stipulated in the technical regulations on fire safety in
constructions.
Provisions for carrying out the works
2.3.14 To ensure airborne sound insulation during the construction of structures, special
attention shall be paid to:
ensuring compliance with the provisions stipulated in the design with regard to
the minimum thicknesses of the propagation path closing elements (to ensure
their necessary mass);
filling the joints during masonry works and sealing the joints when installing
prefabricates and closing elements.
2.3.15 When installing double walls and suspended ceilings, it is prohibited to form any
rigid contacts between the two layers, other than those that are potentially stipulated in the
design.
2.3.16 Proposals for choosing architectural design concepts for residential buildings
depending on the number of apartments grouped around the stairway, the number of
rooms and the type of stairway used.
2.3.16.1 The acoustic design of residential buildings with structures made of reinforced
concrete frames and structural walls made of masonry and reinforced concrete (whether
prefabricated or monolith) involves the implementation of a set of noise protection measures
in order to ensure acoustic comfort as an integrated part of the overall quality of the
dwelling.
30
2.3.16.2 The architectural design parti for a section shall be chosen depending on the
number of apartments in an entrance, the number of rooms in an apartment and the way in
which the stairwell is positioned:
1. enclosed (bordered by the apartment walls);
2. with 1–3 exterior sides.
For dwellings located along roads with intense traffic, the habitable rooms shall
normally be positioned facing the quiet area,
- in two-room apartments - the bedroom;
- in apartments with more rooms - at least two rooms, preferably bedrooms.
If this layout is not possible, special measures shall be taken to insulate the
envelope elements — mainly the windows — and provide special room ventilation
equipment for the summer period to help avoid opening of the windows as much as possible.
The spaces in the neighbouring apartments that have similar functions shall usually
be positioned adjacently (kitchens next to kitchens, bathrooms next to bathrooms, bedrooms
next to bedrooms, etc.).
It is prohibited to install lifts or waste chutes near habitable rooms (living rooms,
bedrooms) without taking insulation measures, obtained as a result of calculations carried
out by specialists in the field.
3. PROTECTION OF FUNCTIONAL UNITS IN BUILDINGS
AGAINST IMPACT NOISE
A functional unit shall be protected against impact noise primarily by means of:
- protective measures implemented at the source (which lead to a reduction of the noise
emitted by the sources) in accordance with paragraph 3.1.
- protective measures implemented along the propagation paths in accordance with
paragraph 3.2.
3.1. Protective measures implemented at the source
3.1.1. The protective measures implemented at the source aim to:
- regulate use of the sources and ensure that these are selected appropriately;
- reduce the vibration level induced in the structural element subjected to the
action of the respective source.
3.1.2. Regulating the usage of sources and selecting them appropriately must lead to
minimising the dynamic stresses created by their action. The sources referred to in this
chapter are:
- impact actions resulting from normal operation of the buildings (objects
falling, moving furniture, people walking about, etc.);
- operation of the machines, equipment or installations within the building.
3.1.3. The vibration level induced in a structural element subjected to the action of the
given source shall be reduced by installing energy dissipation systems (elastic supporting
elements for machines, equipment and installations, elastic flooring for impact actions) at
the place of contact between the source and the element.
31
Under the conditions specified above, the vibration level shall be calculated in
accordance with the provisions stipulated in the technical regulation on the design and
implementation of noise and anti-vibration protection measures in industrial buildings.
Elastic elements for supporting the installations (pipes, reinforcements, etc.) shall be
designed in accordance with the provisions stipulated in Chapter 4 of this regulation.
Elastic flooring for impact actions shall be designed in accordance with sub-chapter
3.2. of this regulation.
When choosing the dimensions of energy dissipation systems, special care shall be
taken to ensure that the structural elements on which these systems are installed have the
required stiffness.
3.2.
Protective measures implemented along the propagation paths
3.2.1. The protective measures adopted along structural noise propagation paths must
comply with the following requirement:
Lvef  f   Lvnec f 
(vibrations)
(3.1)
where:
Lves  f   Lvs  f   Lvadm f 
(vibrations)
(3.2)
where:
Lvs  f  - vibrational strength of the structural element affected by the given source
(vibrations);
Lvadm  f  - permissible vibrational strength for the delimiting element of the protected
functional unit (vibrations).
The level “ Ladm  f  ” shall be deducted depending on the permissible noise level
corresponding to the functional unit being protected.
v
v
For small rooms (with a volume of less than 100 m3), the level “ Ladm  f  ” can be
deducted with the relationship:
Lvadm  f   Ladm  f   C r  10 lg
4S
 80
A f 
(vibrations)(3.3)
where:
Lvadm  f  - permissible noise level for the functional unit being protected (dB);
C r - emission characteristic of the structural element affected by the source (dB);
S – surface of the structural element which emits noise in the functional unit (dB);
A(f) – equivalent sound absorption area of the functional unit (m2A.U.).
Note: The emission characteristic “Cr” for reinforced concrete flooring with a surface
area of up to 25m2 and a thickness of 8–16 cm shall have the values shown in Figure 3.1.
32
Emission characteristic “Cr” for reinforced concrete elements with a surface
area ≤ 25 m2 and a thickness of 8–16 cm
Figure 3.1
“ Lef  f  ” is the actual vibration level reduction obtained along the propagation paths
depending on the distance between the source and the receiving space, as well as the
isolation measures adopted.
v
The reduction “ Lef  f  ” can be determined by:
v
-
acoustic measurements, whether they are carried out in situ or in a
laboratory (using models);
- calculation.
The usable frequency range to be taken into consideration shall depend on the spectral
characteristics of the source.
3.2.2. The reduction “ Lef  f  ” shall be determined by means of acoustic measurements in
accordance with the provisions of STAS 12025/1.
v
3.2.3. The reduction “ Lef  f  ” can be determined by calculation, for guidance, along the
most unfavourable structural route, using the relationship:
v
Lvef  f    Lni  f 
i
(vibrations)
(3.4)
where “ Li  f  ” is the propagation attenuation achieved due to implementing the isolation
measure “i” (vibrations).
The structural noise propagation attenuation referred to in this regulation is:
v
a) attenuation by distance Lad  f  ;
b) attenuation due to sudden cross-section changes in the plane of a structural
v
element Ls  f  ;
v
v
c) attenuation in the corners (90°) Lc  f  ;
33
d) attenuation at cross junctions Lic  f  ;
v
e) attenuation at T-junctions Lit  f  ;
v
v
f) attenuation in the joints Lr  f  .
3.2.3.1.
The level of attenuation by distance Lad  f  can be calculated with the
relationship:
v
Lvad  f   8.6d (vibrations)
(3.5)
where:
 - internal damping coefficient of the material used to make the structural element
through which propagation occurs (s/m);
 - pulsation corresponding to the frequency “f” taken into consideration (Hz);
d - distance between the points in which the attenuation is calculated (m).
v
v
v
v
3.2.3.2.The attenuation levels Ls  f  , Lc  f  , Lic  f  , Lit  f  shall be determined with
the relationship:
Lv  f   R v  f   10 lg
where:
z1  f 
z2  f 
(vibrations)
R v  f  is the vibration attenuation index obtained.
(3.6)
v
for sudden changes in cross-section ( Rs  f  in accordance with the diagram
shown in Figure 3.2.a;
v
- for the propagation of vibrations through the corners ( Rc  f  ) in accordance
with the diagram shown in Figure 3.3.b;
v
- for the propagation of vibrations through cross junctions ( Ric  f  ) in
accordance with the diagram shown in Figure 3.2.c;
v
- for the propagation of vibrations through T-junctions ( RiT ( f ) ) in
accordance with the diagram shown in Figure 3.2.d.
Z1(f) is the impedance of the structural element from which the vibrations are
propagated;
Z2(f) is the impedance of the structural element in which the vibrations are
propagated.
-
34
(vibrations
)
Figure 3.2.a Value of the vibration attenuation index for sudden changes in cross-section
(vibrations
)
Figure 3.2. b Value of the vibration attenuation index for vibrations propagated through the
corners
(vibrations
)
35
Figure 3.2. c Value of the vibration attenuation index for vibrations propagated through
cross junctions
(vibrations
)
Figure 3.2. d Value of the vibration attenuation index for vibrations propagated through Tjunctions
Note: For approximate calculation, the ratio Z1(f)/Z2(f) can be replaced with the ratio
m1/m2, where m1, m2 are the masses of the two structural elements considered per unit of
surface area.
3.2.3.3.
A total attenuation of the amplitude of the vibrations shall be obtained during
their propagation through joints that do not contain insulating materials (joints with an air
layer).
Note: If, for reasons other than acoustic ones, the joints are equipped with isolation
products, local resonance phenomena shall occur, which can amplify the amplitudes of the
vibrations transmitted through them. In these situations, the solution implemented must be
checked by in situ acoustic measurements.
For structural elements such as walls intersecting at right angles, it is preferable for
the joint provided with insulating material to be located within the plane of the wall to which
vibrations are transmitted from the other wall.
3.2.4. In accordance with this regulation, impact actions developed on the floor slabs of
buildings due to their normal operation shall be taken into consideration.
3.2.5. The normalised impact noise level Ln(f) shall be determined using the values of the
sound pressure level Li (f) measured in the sound receiving room - in accordance with SR
EN ISO 10140-3 (in a laboratory) or SR EN ISO 140-7 (in situ).
3.2.6. From a practical point of view, it shall be considered that a functional unit complies
with the impact sound insulation requirements if its ceiling meets the following requirement:
L’n,w,ef ≤ L’n,w,nec
(dB)
(3.7)
where:
36
L’n,w,ef -
the actual normalised impact sound insulation index of the bare floor slab
with flooring, determined in accordance with SR EN ISO 717-2, SR EN
ISO 717-2/A1 and SR EN ISO 717-2/C91, using the Ln(f) values;
L’n,w,nec - the necessary normalised impact sound insulation index for the bare floor
slab with flooring, stipulated in Part III, code C 125/3-2012.
3.2.7. The impact sound insulation capacity of a floor slab shall, essentially, depend on the
elasto-damping properties of the flooring applied to it.
Note: Bare floor slabs or floor slabs covered with regular cold flooring, which are
frequently used in residential and social-cultural buildings, do not meet the impact sound
insulation requirements.
ANNEX 9 gives the values of the normalised equivalent impact sound insulation
indices Ln,eq,o,w for bare floor slabs made of reinforced concrete of various thicknesses.
Design elements
3.2.8. The impact sound insulation requirements shall be complied with, primarily, by
installing flooring which, together with the bare floor slab, must ensure the necessary impact
sound insulation index.
3.2.9. The normalised impact sound insulation index for a bare floor slab with flooring,
Ln,w ,ef, can be determined by:
- acoustic measurements carried out in situ or in a laboratory;
- calculation.
The frequency range taken into consideration shall be 100–3 150 Hz.
3.2.9.1.
The index Ln,w ,ef shall be determined by measurements in accordance with the
provisions of SR EN ISO 10140-3 (in a laboratory) or SR EN ISO 140-7 (in situ).
3.2.9.2.
The index Ln,w ,ef shall be determined by calculation using the relationship:
Ln,w = Ln,eq,o,w - Δ Lw
(dB)
(3.9)
where:
Ln,eq,o,w - normalised equivalent impact sound insulation index of the bare floor slab;
Δ Lw - impact sound improvement index.
The improvement Δ Lw shall be determined by carrying out acoustic measurements in
a laboratory or in situ, in accordance with the provisions of SR EN ISO 10140–3 or SR EN
ISO 140-7.
ANNEX 9 gives the values of the improvement ΔLw corresponding to the main types
of flooring that are frequently used in civilian buildings.
3.2.10. Floating slabs can be used if a special level of impact sound insulation is required.
Floating slabs shall have the structure shown in Figure 3.3.
37
wall
wall mounted plinth
(must not come in contact with the flooring)
vertical elastic layer
continuous flooring
floating slab or blanket
plinth
elastic joint
tile flooring
horizontal elastic layer (cold-hardened polystyrene,
mineral wool with  > 100 kg/m3 etc.)
polyethylene sheet for protecting the elastic layer
supporting floor
slab
Figure 3.3
a - tile flooring
b - continuous flooring
ANNEX 9 gives the Δ Lw values for a few floating slab structures.
3.2.11. The acoustic design of floor slabs which separate functional units with different
hygrothermal environments shall aim to simultaneously ensure acoustic and hygrothermal
comfort conditions.
38
3.2.12. The acoustic design of flooring structures made of flammable products shall take
into account the specific activities carried out in the respective functional unit, to ensure
compliance with the requirements stipulated in the technical regulations on fire safety in
constructions.
Provisions for carrying out the works
3.2.13. To ensure the necessary impact sound insulation capacity (stipulated in the design)
when supplying products and making different types of floorings with a parquet wear layer,
PVC flooring or mats, special attention shall be paid to the following:
- compliance with the design or internal manufacturing guidelines with regard to
the minimum thickness of soundproof underlayers;
- installation of the elastic layers of the flooring so that they do not become rigid
during application.
3.2.14. When installing “floating slab” flooring, it shall be made certain that no rigid bridges
are created between the slabs and the bare floor slab during application.
4. PROTECTION AGAINST NOISES PRODUCED BY EMBEDDED
INSTALLATIONS AND EQUIPMENT IN BUILDINGS
4.1
Ventilation and air conditioning systems (VAC)
This sub-chapter refers to the measures required in order to reduce the noise level
produced by ventilation and air conditioning systems in the functional units they serve, as
well as in ventilation stations.
Design elements
4.1.1. A functional unit in a residential, social-cultural or industrial building shall be
deemed compliant with the acoustic comfort requirements (for noise produced by the
operation of ventilation and air conditioning systems) if the following requirements are met:
a) in rooms within residential and social-cultural buildings where the interior equivalent
noise level is limited due to exterior noise sources, the noise level due to the operation of
VAC systems shall have to comply with the values given in Tables 5 and 29 of Part III, code
C125/3-2012;
b) in rooms within residential and social-cultural buildings where the interior equivalent
noise level is limited due to the simultaneous action of noise sources located outside of the
functional units and equipment operating inside these units, the noise level due to the
operation of VAC systems shall have to comply with the values given in Tables 9 and 33 of
Part III, code C125/3-2012;
c) in industrial halls, the noise level due to the operation of VAC systems must be at least
5 dB lower than the background noise level produced by the main equipment operating in
the respective halls.
4.1.2. The noise produced during the normal operation of VAC systems in buildings can
propagate via two main routes:
a) as airborne and structural noise, from the VAC station to the other rooms;
b) as aerodynamic noise, along the ventilation channels.
39
4.1.3. Airborne noise propagating from the VAC station to the adjacent rooms is emitted by
the surfaces of the equipment that is vibrating due to its normal operation.
Structural noise propagating from the VAC station to the other rooms is emitted by
the structural elements and installations that are vibrating due to the solid conduction and
vibrations produced by equipment operating normally.
Aerodynamic noise propagating along the ventilation channels is produced primarily
by operating fans connected to these channels and shall depend on the particularities of the
air path (air vents, geometric characteristics of the pipes, air outlets, etc.).
The main noise sources located inside VAC stations are:
- fans;
- electric actuation motors;
- compressors;
- electric pumps.
4.1.4. The airborne noise level produced by noise sources located inside a ventilation
station shall be determined by direct measurement, in accordance with STAS 7150.
If the level of airborne noise produced by the equipment located within a VAC
station is not known when designing the station, it shall be determined by calculation.
The overall noise level, characteristic to a VAC station in which several pieces of
equipment such as those mentioned above operate, shall be obtained by direct measurement
or by adding up the noise power levels specific to each piece of equipment (measured or
calculated).
4.1.5. If the overall noise level in a VAC station, determined in accordance with point
4.1.4, is higher than 87 dB(A), measures shall be adopted to reduce the noise level, in the
following preferential order:
a) acoustic optimisation of the equipment;
b) acoustic screening or encasing of the noise sources, in accordance with the provisions
stipulated in Chapter 2;
c) applying a sound-absorbing treatment in the room.
4.1.6. To prevent transmission of the noise produced by the equipment operating in VAC
stations to the functional units within the building, these should be located in outbuildings,
away from the main buildings.
When this recommendation cannot be followed, the partitioning elements in the
VAC station and its adjacent rooms shall be dimensioned in accordance with the airborne
sound insulation requirements stipulated in STAS 6156, Table 4.
When the ventilation equipment is installed directly inside production spaces, the
equipment must be chosen so that its characteristic airborne noise level does not exceed the
permissible level for the respective space.
40
Since the airborne sound insulation of rooms adjacent to a VAC station requires the
installation of partitioning structural elements with high insulation indices R’w, which
usually cannot be achieved for single-layered elements of normal dimensions, buffer spaces
should be provided and measures should be adopted to reduce the noise level within the
station, as stipulated in point 4.1.5.
4.1.7. The following recommendations shall be taken into account during acoustic
optimisation of the equipment:
a) the fans must be chosen from catalogues, so that their operating point is located near or
close to the point of maximum output. Figure 4.1.1 shows the diagram for the noise (or
acoustic power) variation of a centrifugal fan as a function of the output;
a - axial fans
b - centrifugal fans
V- air volume delivered (m3/h)
Vopt – optimum air volume (m3/h)
Figure 4.1.1 variation of the acoustic power level of the fans as a function of the “V /
Vopt” ratio
b) fan shrouds must be checked to ensure that air circulation through the fan does not
create vibrations with velocity amplitudes higher than 0.7 mm/s. If this value is exceeded,
the shrouds shall be reinforced with vibration damping layers;
c) equipment with rotating parts installed on straight or cranked shafts shall be chosen so
that no imbalanced masses are present, the rotation movement does not create shocks and
the bearings do not malfunction.
4.1.8. For electric motors in VAC stations which produce a noise level L  90 dB (A), the
reduction in the noise level produced during their normal operation shall be obtained by
acoustic encasing, as shown in Chapter 2.
Figure 4.1.2 shows a theoretical example of a soundproof casing.
41
1 – 2 mm steel sheet; 2 – sound-absorbing treatment ( for example: mineral wool); 3 –
perforated sheet, with a hole percentage of 20 %; a – cooling air inlet; b – cooling air
outlet.
Figure 4.1.2 Casing of an electric motor
4.1.9. The noise level in VAC stations shall be reduced by applying sound-absorbing
treatments, in accordance with the provisions stipulated in Chapter 2.
4.1.10. The following measures shall be taken to limit the propagation of structural noise
produced due to solid conduction of the vibrations of equipment operating normally:
a) the equipment shall be installed on damping systems of suitable dimensions;
b) the fans and ventilation channels shall be connected by elastic connectors (e.g. rubber or
rubber sheet joints whose acoustic impedance is significantly lower than that of steel sheet);
c) the ventilation channels shall be fixed to the structural elements by means of elastic
devices (anti-vibration supporting systems). Channels with low and medium air flow rates
(Q  40 000 m3/h) shall be fixed to the ceiling using standardised vertical support devices,
providing that a rubber band with a hardness of 30–50° Shore and a minimum thickness of 2
cm is interposed between the bracket, the tie rods and the channel. For higher air flow rates
(Q > 40 000 m3/h), the channel shall be fixed to the ceiling using elastic retaining devices,
as stipulated in Figure 4.1.3.
42
Concrete slab
device
providing
support onto
the steel joint
retaining
plate
steel
spring
ventilation
ducting
tubular clamp
a) version with a steel spring
damper
b) version using a rubber
spring support
Figure 4.1.3 Elastic devices for fixing ventilation channels to the ceiling
The channels shall be fixed to the walls using standardised devices for horizontal
support, providing that a rubber band with a hardness of 30–50° Shore and a minimum
thickness of 2 cm is interposed between the bracket and the ventilation channel. Passage of
the ventilation channels through walls shall be ensured in accordance with Figure 4.1.4.
4.1.11. The aerodynamic noise propagating along the ventilation channels can enter a room
either directly, through the air inlets or outlets, or indirectly, being emitted by the channel
walls.
In the first situation, the aerodynamic noise level (overall or for a given frequency)
produced when the air exits (or enters) the channel shall be determined with the relationship
Laer  Laer
 L , (dB)
v
(4.1.1)
crossing section
main air channel
elastic joint made
of rubber sheet
Figure 4.1.4 Passage of the ventilation channels through walls
Laer
(dB) - the aerodynamic noise level produced by the fan, determined when the air enters
v
43
or exits the channel;
L  (dB) - the aerodynamic noise level due to air swirls occurring when the air jet
passes through the outlet or inlet grates.
In the second situation, the aerodynamic noise level (overall or for a given
frequency) inside the room (near the channel) shall be determined with the relationship
Laer  Laer
v  R  f  , (dB)
(4.1.2)
where
Laer (dB) - the aerodynamic noise level produced by the fan, determined in the point
taken into consideration (inside the channel);
R f  (dB) - airborne noise attenuation index corresponding to the channel wall at a
certain frequency f.
4.1.12. The aerodynamic noise level produced by the fan shall depend on the speed at which
the air jet travels through the channels, the acoustic power of the fan and the attenuation
occurring due to the noise propagation conditions present in the channel.
To ensure the normal acoustic operation of the ventilation system, the speeds at which the
air jet travels through the channels must not exceed the values given in Table 4.1.1.
Table 4.1.1
Maximum permissible air circulation speeds for ventilation channels installed in
regular and social-cultural rooms
Maximum permissible circulation speeds
Ite
(m/s)
m
Type of channels
Regular
Public
audition
halls,
No
rooms
libraries and hospital wards
0
1
2
3
1
Main channel (directly from the
fan)
Secondary channel (branch)
Air outlets and inlets (free section)
2
3
5-8
3.6-6
3-5
3-5
2.5-4
2.5
When the requirements stipulated in Table 4.1.1 are complied with, the aerodynamic
noise level can be determined with the relationship
Laer
v  Lv , D  10 lg S  Lc , (dB)
(4.1.3)
where:
Lv , p (dB) - the acoustic power level of the fan, either measured or calculated;
S (m2) - cross-sectional area of the channel at the point where it exists the fan;
Lc (dB) - attenuation of the aerodynamic noise level due to the propagation
conditions present in the ventilation channels.
44
Acoustic calculations shall be carried out, using relationships (4.1.1) and (4.1.3), for
noise levels in 1/1 octave frequency bands, within a frequency range of at least 63–
4 000 Hz.
4.1.13. The overall acoustic power level of the fans shall be determined by direct
measurements, in accordance with STAS 12203/1.
If the overall acoustic power level of the fans is not known during the design stage, it
shall be determined by calculation.
4.1.14. The aerodynamic noise level attenuation due to the air jet propagation conditions
present along the ventilation channels shall be obtained naturally (straight sections, bends,
sudden section changes, branches), as well as using special procedures.
The main special procedures used are:
a) lining the channels with sound-absorbing products;
b) inserting expansion chambers along the routes;
c) inserting various types of attenuators along the routes.
The expansion chambers shall be obtained by suddenly enlarging the ventilation
channel for a certain length. They produce reactive and active attenuation.
Attenuators are structural elements inserted along the route of a ventilation channel,
which contain surfaces that have been subjected to intense sound-absorbing treatments and
are installed mainly parallel to the direction of the air jet. They produce predominantly
active acoustic attenuation.
Frequently used active attenuators are:
a) single circular active attenuators;
b) circular active attenuators with a sound-absorbing bulb;
c) lamellar rectangular active attenuators;
d) rectangular active attenuators with baffles.
Single circular active attenuators represent the industrial application of the procedure
for providing a sound-absorbing lining (Figure 4.1.5).
Circular active attenuators with a sound-absorbing bulb are presented in Figure
4.1.6.
Figure 4.1.5 Single circular active
attenuators
Figure 4.1.6 Circular active attenuators with
a sound-absorbing bulb
Lamellar rectangular active attenuators shall be created by installing a given number
of sound-absorbing lamellae of a certain thickness, which are parallel to each other (Figure
4.1.7).
45
leading edge
of the lamella
Figure 4.1.7 Lamellar rectangular active attenuators
Rectangular active attenuators with baffles are presented, in principle, in Figure 4.1.8.
L
N ;
D
2ab
D
;
ab
Figure 4.1.8 Rectangular active attenuators with baffles
The aerodynamic noise level attenuation due to the air jet propagation conditions
present along the ventilation channels shall be calculated in accordance with point “c” of
Annex 11.
4.1.15. The acoustic attenuation obtained during the discharge or intake of air from (into) a
room through a ventilation hole (considered without a grate) shall be determined in
accordance with point “d” of Annex 11.
4.1.16. If the ventilation hole is equipped with a grate, passage of the air jet through the grate
will produce a noise whose overall level can be calculated in accordance with point “e” of
Annex 11.
Also, for anemostats installed on the ceiling, the overall noise level due to passage of the air
jet can be calculated in accordance with point “c” of Annex 11.
The overall noise level due to the discharge or intake of air from (into) a room shall
be determined by adding up the noise power levels obtained as specified above with the
level mentioned in point 4.1.15.
4.1.17. Aerodynamic noise entering a room through air inlet or outlet holes shall propagate
inside these holes in different ways, depending on the existing geometric characteristics. The
airborne noise level at a point inside the room, located at a distance d from the air inlet or
outlet, shall be determined with relationship
L  Laer  LQ, A, d  ,
(dB)
(4.1.4)
where Laer (dB) is the aerodynamic noise level entering the room, determined in
accordance with relationship (4.1.1), and LQ, A, d  is the acoustic correction of the room,
46
which depends on the directivity factor Q, the equivalent sound absorption surface A of the
room and the distance d from the ventilation hole to the point taken into consideration.
4.1.18. For rooms crossed by ventilation channels, the channel walls shall be checked to
make sure that their airborne sound insulation capacity does not allow emission, in the
rooms that it crosses, of a noise with an acoustic level higher than the level permitted in the
respective rooms. The airborne noise level in the rooms can be determined with relationship
(4.1.2).
4.1.19. Special care shall be taken to prevent the transmission of noise between two rooms
with different acoustic environments, through the ventilation channels (by implementing
sound insulation measures). In these situations, the insulation index R’w for the walls of the
ventilation channels must be at least equal to the insulation index corresponding to the
partition wall between the two rooms.
noise
sources
room with a
low noise level
a) supplying rooms with air
through separate channels
noise
sources
room with a
low noise level
b) installation of an attenuator along
the channel which supplies the room
with a low noise level
Figure 4.1.9 Possibilities of attenuating the noise transmitted between two rooms by cross-talk
Figure 4.1.9 shows a few possibilities of insulation between rooms with different
acoustic environments, which are crossed by ventilation channels.
4.1.20. VAC systems shall be designed in accordance with the regulations on fire safety in
constructions and the fire protection measures applicable to insulation systems and acoustic
treatments.
Provisions for carrying out the works
4.1.21. When installing equipment in a VAC station, special care shall be taken to:
a) comply with the dimensions of the foundation block, as well as the dimensions and
quality required for the anti-vibration support products;
b) comply with the types of fans stipulated in the design;
c) comply with the types of products stipulated for elastic joints.
4.1.22. When manufacturing the required ventilation channels and acoustic attenuators,
space care shall be taken to:
a) comply with the metal sheet thicknesses stipulated in the design;
b) comply with the types of sound-absorbing products, as well as their thicknesses
47
stipulated in the design.
4.1.23. When installing ventilation channels, special care shall be taken to:
a) comply with the details for fixing them to rigid structural elements;
b) comply with the details for passing through walls and floor slabs (making sure to
comply with the fire protection requirements).
4.2
Sanitary installations
The present sub-chapter refers to the measures required in order to reduce the noise
level inside a functional unit, due to the operation of sanitary installations located outside or
inside the respective unit, which are activated from outside the unit.
Design elements
4.2.1. The noise sources taken into consideration in this sub-chapter are:
a) domestic water supply system;
b) water supply pipes and sewer pipes;
c) sanitary fittings and fixtures.
4.2.2. To ensure that the permissible noise limits are complied with, it shall be considered
that a functional unit meets the sound insulation requirements for airborne noise produced
by domestic water supply systems, central heating units and thermal sub-stations if the
sound insulation indices R’w for the partitioning structural elements are higher than or equal
to 61 (+9) dB.
Since partitioning single-layer elements of regular dimensions cannot provide
airborne sound insulation of the rooms inside residential apartments against drying rooms,
laundries, domestic water supply systems, central heating units and thermal sub-stations, as
well as other spaces with a high noise level, buffer spaces should be introduced or measures
should be adopted to reduce the noise level in the installation stations.
4.2.3. The measures for reducing the noise level produced by water supply systems shall be
applicable to the buffer vessel, the electric circulation pumps, the actual water pressure tank
and the air compressor.
48
mineral wool plates - 5 cm
wood fibreboard
mineral wool plates - 5 cm
3 cm mineral wool
plates
wood fibreboard
mineral wool plates
- 5 cm
mi
n.5 pump
0
min. 25
cork
Figure 4.2.1 Model of a double casing
4.2.4. The noise level due to the operation of buffer vessels shall be reduced by:
a) sound insulation of the buffer vessel, using anti-vibration treatments calculated
appropriately;
b) correct installation of the water supply pipe, whose end must reach as close to the
bottom of the buffer vessel as possible (maximum 15 cm away from it).
4.2.5. The noise level produced by the electric pumps used by water supply systems shall
be reduced by:
a) installing a sound-absorbing ceiling in the room where the water supply system is
located (calculated and designed in accordance with Chapter 2);
b) encasing the electric pump in accordance with the provisions stipulated in Chapter 2 (an
example of a double soundproof casing is shown in Figure 4.2.1);
c) placing the electric motors on foundations, using anti-vibration mounts.
Whenever possible, electric pumps should be installed in a room located outside of
the building (Figure 4.2.2).
49
PLANE
CROSSSECTION
sound
insulation
Joint
min. 0.5 m
pipes
soundproo
f door
PUMP ROOM
BASEME
NT
min. 0.5 m
Figure 4.2.2 Construction of the pump rooms located outside of buildings - rough layout
4.2.6. The noise level produced by the electric pumps and transmitted via the water supply
pipes shall be reduced by:
a) inserting elastic connectors (e.g. rubber) between the electric pumps and the pipes, in
accordance with the details shown in Figure 4.2.3;
min. 700
steel spring reinforced
rubber hose (ø40–200 mm
DETAIL A
Figure 4.2.3 Details of elastic connectors
b) correct installation of a water supply system along the discharge routes of the electric
pumps, in accordance with Figure 4.2.4.
50
pump
users
pump
water
tank
water
tank
users
a) existing situation
b) recommended situation
Figure 4.2.4 Systems for installing the water pressure tank on the discharge route of the electric
pump
4.2.7. The noise level due to turbulent water flow through the pipes shall be reduced by:
a) limiting the water flow velocity (for regular pipes with diameters of less than 3/4'', the
flow regime can be considered acceptable if the water flow velocity is less than 2 m/s);
b) using pipes with the smoothest inner walls possible and eliminating any deposits
occurring inside hot water pipes.
4.2.8. The noise level generated by sudden section or direction changes shall be reduced
by:
a) ensuring slow transition from one section to another;
b) installing as few straight elbows as possible in the network;
c) replacing regular T-shape branch pipes by tangential branch pipes.
4.2.9. Substances with strong internal damping properties (e.g. filler, mastic, mineral wool)
shall be applied to the exterior surface of the pipes in order to reduce their vibration
amplitude.
sound insulation (mineral wool mats
with a density of 90 kg/m3)
structural element
protection pipe
min. 6 cm
sealing element
rubber gasket
pipe
Figure 4.2.5 Sound insulation of pipes where passing through structural elements
51
4.2.10. The following measures shall be taken to prevent the vibrations of the pipes from
being transmitted to the structural elements:
a) airtight contact elastic elements shall be installed in the locations where the pipes pass
through structural elements (Figure 4.2.5);
b) cushioning materials (e.g. rubber, cork, etc.) shall be inserted between the pipes and
their retaining clips (Figure 4.2.6);
c) the clips shall be fixed onto structural elements using dowel pins insulated with
damping products (e.g. cork, rubber, etc.), as shown in Figure 4.2.7.
cushioning
product
Wooden
dowel pin
Cork
Figure 4.2.6 Insulation between pipes and
clips using cushioning products
Figure 4.2.7 Fixing method for insulated
dowel pins
4.2.11. The noise level due to the passage and discharge of water through the valves shall be
reduced, in order to ensure its compliance with the permissible noise limits, in accordance
with the following procedure:
52
a) the fittings shall be chosen from the manufacturers’ catalogues making sure that their
specific noise level corresponds to the permissible noise level stipulated for the functional
unit adjacent to the room in which the respective fitting is installed. The specific noise levels
for some regular fittings used in sanitary installations are given in Table 4.2.1.
b) the sudden narrowing of the pipe sections at the fittings should be avoided.
Table 4.2.1
Types of fittings depending on the specific noise level due to water flowing with a
pressure of 0.3 Mpa
Item Specific noise level (LS) of Types of
Code
No
the fittings (dB)
fittings
0
1
2
3
231-1/2”; 261-3/8” (measured at the
1
35
Valves
operating pressure)
327-1/2”; 361-1/2” with flexible
2
35-40
Tap sets
shower kit; 374-1/2”; 382-1/2”
Valves
113-1/2”; 251-1/2”
Tap sets 395-1/2”; 331-1/2”
3
40-45
111-3/8”; 111-1/2; 121-1/2” ; 221-1/2”;
Valves
215-1/2”; 215-5/4”; 215-1”; 212-1/2”
Tap sets 301-1/2”; 354-1/2” ; 331-1/2”; 341-1/2”
4
45
Valves
111-2/3”; 111-1”; 121-1”; 212-3/4”
4.2.12. The noise level due to water falling in various sanitary fixtures (bath tubs, sinks,
tanks, etc.) shall be reduced by:
a) deviating the water jet so that its free fall is replaced by an extension of the sanitary
fixture along the vertical or oblique surfaces (e.g. guiding the water towards the sides and
not the bottom of bath tubs);
b) manufacturing shower hoses from rubber or flexible metallic tubes;
c) installing water calming and dissipating devices on the showers and fittings (e.g.
perlators).
4.2.13. The following constructive measures shall be taken to prevent the vibrations from
being transmitted to the structural elements:
a) installing the sanitary fixtures on walls with a high mass (but never on walls separating
quiet rooms), using elastic gaskets and a non-rigid retaining element (Figure 4.2.8);
b) separating the bath tub and boiler from the bathroom floor and walls using cushioning
products (Figure 4.2.9);
perlator
rubber gaskets
piece for deviating the
water jet
perlator
intermediary pieces
made of rubber hose
cushioning
products
Figure 4.2.8 Installation of sanitary fixtures
using a non-rigid retaining element
Figure 4.2.9 Separation of the bath tub
using cushioning products
4.2.14. Habitable rooms in residential buildings, hostels, hotels and guest homes shall be
protected by:
53
a) avoiding the installation of sanitary fixtures in rooms adjacent to habitable rooms
(Figure 4.2.10);
b) avoiding the installation of sanitary fixtures on walls delimiting habitable rooms
(Figure 4.2.11).
Be
dr
oo
m
Ki
tc
he
n
Livin
g
room
Kitchen
Bath
room
Co
Bath rri
room do
r
Figure 4.2.10 Recommended positioning of
sanitary fixtures in relation to the other
rooms
Figure 4.2.11 Recommended installation of
sanitary fixtures on a wall which does not
delimit habitable rooms
4.2.15.
The measures for reducing the noise level produced by sanitary installations shall
be designed in accordance with the regulations on fire safety in constructions.
Provisions for carrying out the works
4.2.16. To reduce the noise level in sanitary installations, during their installation it shall be
made certain:
a) to insert cushioning products between the pipes and their retaining clips;
b) to secure the retaining clips using dowel pins insulated with dampers;
c) to attach pipes to the ceiling using non-rigid anchoring elements with elastic
suspension;
d) to install the sanitary fixtures on high mass walls, using cushioning products (sanitary
fixtures shall not be installed on walls located between functional units or walls delimiting
quiet rooms);
e) to apply elastic sealant at the place where the pipes pass through walls and floor slabs;
f) to screen the pipes using soundproof masks installed in a non-rigid way.
4.2.17. Any potential modifications to the design, with regard to the products or solutions for
installing sanitary fixtures, shall only be implemented with the approval of the design
engineer.
Provisions for carrying out repairs in existing situations
4.2.18. The procedure for remedying certain existing situations shall start with a mechanical
inspection of the equipment located inside sanitary installation stations.
4.2.19. All connections between the pump and the network shall be undone and the pump
shall be allowed to run on idle, in order to determine whether the noise is transmitted within
the building/structure via an air route or a structural route. If, in this situation, the noise can
be heard in the rooms adjacent to the sanitary installation station, this means that the noise is
transmitted structurally, through the building elements.
4.2.20. If the noise is transmitted structurally through the building elements, the equipment
54
shall be supported on anti-vibration dampers.
4.2.21. If the noise is transmitted structurally through the pipes, noise level attenuation
measures shall be implemented in a differentiated manner, as follows:
a) the attenuation measures required if the noise level is between 35 and 40 dB(A) are:
- inserting elastic connectors between the electric pumps and the pipes;
- installing cushioning elements at the flaps of the return valve;
b) if the noise level inside the rooms is between 40 and 45 dB(A), the measures stipulated
in point a) shall be supplemented with the following measures:
- installing the water pressure tank in series with the electric pumps;
- checking and correcting the points of passage of the pipes through the walls;
c) if the noise level inside the apartments is higher than 45 dB(A), any noise attenuation
measures shall only be taken in cooperation with specialists in acoustics.
4.3. Heating installations
This sub-chapter refers to the measures taken to reduce the noise level produced by
heating installations located in building basements and propagated to the functional units
located on the other storeys.
Design elements
4.3.1. The noise produced during the normal operation of heating installations can
propagate via three main routes:
- airborne noise;
- structural noise;
- aerodynamic noise along the installation channels.
4.3.2. Airborne noise propagating from the heating installation stations to the adjacent
rooms is emitted by the surfaces of the equipment that is vibrating due to its normal
operation.
Structural noise is emitted by the structural elements and vibrating installations due
to solid conduction and the vibrations produced by the equipment operating normally.
Aerodynamic noise propagating along the pipes is produced by the operation of the
injectors and fans connected to these pipes and depends on the characteristics of the aeraulic
route.
The main noise sources located inside heating stations are:
- electric motors;
- fans;
- electric pumps;
- injectors.
4.3.3. The airborne noise level produced by noise sources located inside a heating station
shall be determined by direct measurement in accordance with STAS 7150.
If the airborne noise level produced by the equipment is not known during the design
stage, it shall be determined by calculation, in accordance with point a) of Annex 12.
The overall noise level in a heating station in which several pieces of equipment
operate shall be obtained by direct measurement or by adding up the noise power levels
specific to each piece of equipment (measured or calculated).
4.3.4. The measures in a heating station in order to reduce the level of noise and vibrations
“at the source” shall consist of:
55
- choosing the correct equipment depending on its power, speed, output and pumping
height;
- ensuring the correct maintenance of this equipment.
4.3.5. The airborne noise reduction measures required are:
- solutions for reducing the airborne noise level in installation stations (casings,
screens, sound-absorbing treatments);
- solutions for increasing the airborne sound insulation capacity of the structural
elements which separate the installation stations from the adjacent spaces (double structural
elements, insertion of buffer spaces, etc.);
- mixed solutions (for example, the installation of suspended sound-absorbing ceiling
which reduce the noise level in the station and increase the airborne sound insulation
capacity of the floor slabs).
4.3.6. The structural noise reduction measures required are:
- the correct design and execution of the means of supporting the equipment, using
an elastic layer;
- inserting cushioning products between the pipes and their retaining clips;
- fitting elastic connectors on the pipes.
All these measures shall be chosen and calculated in accordance with the provisions
stipulated in the technical regulation on the design and implementation of noise and antivibration measures in industrial buildings.
4.3.7. The measures for reducing the noise produced by flowing liquid shall be those
presented in paragraphs 4.2.7.–4.2.8.
4.4
Electrical installations
This sub-chapter refers to the measures that need to be taken in order to reduce the
noise level produced inside of a functional unit by the operation of electrical installations
and equipment.
Design elements
4.4.1. This sub-chapter refers to the noise reduction measures that need to be taken into
consideration during the design and construction of electrical power transformer sub-stations
located on the ground floor of buildings, to ensure compliance with the comfort
requirements stipulated in STAS 6156.
4.4.2. To attenuate the transmission of airborne noise so that its level remains within the
permissible limits, partitioning structural elements (walls and floor slabs) must have an
airborne sound insulation index R' w  57  5 dB. An indoor system shall be used for this
purpose, whose walls and floor slabs shall have a double structure provided with a
continuous air gap as shown in Figures 4.4.1–4.4.4.
A sound-absorbing layer of porous plates shall be installed in the gap between the
walls, as well as in the gap between the load-bearing floor slab and the lining floor slab; the
porous plates shall be glued to the load-bearing walls of the building and shall sit freely on
the lining floor slab.
56
Joint wrapped in
tar-soaked rope
Porous soundabsorbing material
with a thickness of
5 mm
Walls made of
ACC strips
Figure 4.4.1 Indoor system for the sound insulation of a transformer sub-station embedded in the
building (PLAN)
57
ACC floor slabs
(roofs)
(dmin=10 cm)
sound-absorbing slabs with a
density of 100 kg/m3 and a
thickness of 5 cm
fired clay masonry element
Figure 4.4.2 Indoor system for the sound insulation of a transformer sub-station embedded in
the building (SECTION A-A)
ACC slab
between slabs
Hardening mortar
Masonry-anchored upport element
with the dimensions of 100 x 100 x
80 (installed one metre apart)
between slabs
SECTION 1 - 1
(by joining two adjacent
strips)
M25 mortar
Figure 4.4.3 Engineering detail of a floor slab (DETAIL A)
58
Figure 4.4.4 Indoor system for the sound insulation of a transformer sub-station embedded in the
building (SECTION B-B)
Figure 4.4.5 Indoor system for the sound insulation of a transformer sub-station embedded in the
building (SECTION C-C)
4.4.3. The wall and ceiling products stipulated in this regulation are for guidance only and
59
can also be manufactured from other products, using a monolith procedure, or from
prefabricates, providing that the weight of the structural element is not lower than 80 kg/m2.
Also, if prefabricated panels are used, care shall be taken to insulate the joints.
4.4.4. To attenuate the transmission of structural noise, the installations located inside the
transformer sub-station shall have their own foundations, separated from the rest of the
building by a continuous joint of at least 5 mm, filled with a cushioning material (Figure
4.4.3, Figure 4.4.4).
4.4.5. To prevent any execution errors that could compromise the designed sound
insulation measures, any changes to the constructive solutions stipulated in the design shall
only be implemented with the approval of the design engineer.
4.4.6. The measures for reducing the noise level produced by transformer sub-stations
located on the ground floor of residential buildings or other functional units (in which
flammable products are used) shall be designed in accordance with the applicable
regulations on fire safety in constructions, in force.
Provisions for carrying out the works
4.4.7. Whenever possible, the interior casing should be built before installing the loadbearing slab that covers the transformer sub-station cell.
4.4.8. If the interior casing is built after the load-bearing slab has been installed, the order
in which the works are to be performed shall be the following:
a) 3 out of 4 interior walls shall be erected;
b) the ACC ceiling slabs (or another light roof structure) shall be applied, supported on the
two opposite walls already in place;
c) the last wall shall be erected.
4.5
Embedded equipment
This sub-chapter refers to the measures that need to be taken in order to reduce the
noise level produced inside a functional unit by the operation of embedded equipment.
Design elements
4.5.1.The noise sources taken into consideration in this sub-chapter are:
a) elevators/lifts and other equipment for vertical transport;
b) escalators, moving walkways;
c) electric generator sets and electrical transformer stations.
4.5.2. This sub-chapter takes into consideration the following noise sources present in
elevator installations:
a) electro-mechanical sub-assemblies of the installation (motor-generator groups, motors,
reducers, fans, hoists, etc.);
b) the cabin and annexes.
The electro-mechanical sub-assemblies of the installations are usually installed in the
60
hoist chamber, on the top storey of the building. Their operation produces structural noise
and airborne noise which propagate through the building along the paths shown in Figure
4.5.1.
61
Figure 4.5.1 Air propagation paths for the noise produced by the elevator installation
When operating normally, the cabin shall produce pressure vibrations along the
entire route. These pressure vibrations can create swirling aerodynamic noises which shall
be received predominantly near the access doors to the lift shaft.
When the lift stops by a floor platform and people enter and exit the cabin,
significant noises can occur during:
a) closing of the access doors to the elevator shaft;
b) closing and opening of the cabin doors;
c) activation of the cabin floor.
These noises shall propagate by air, predominantly along the elevator shaft, and
through the access doors towards the corridors of the building.
4.5.3. Airborne and structural noises produced by elevator installations can be controlled
by:
a) implementing noise reduction measures at the source;
b) implementing solutions that limit airborne or structural noise propagation;
c) using the installation in a rational way.
4.5.4. In the case of electro-mechanical sub-assemblies, the measures for reducing the
airborne noise level at the source shall imply:
a) choosing electrical equipment (motor-generator groups, motors) with a low noise level,
not equipped with a cooling system or fitted with quiet cooling fans;
b) preferential use of vertical axis motors instead of horizontal axis motors;
c) predominant use of sliding bearings instead of roller bearings;
d) preferential use of hoist oil brakes instead of electromagnetic shoe brakes;
e) use of the quietest switches possible (by using electromagnets with damping devices,
for dynamic switches, or by using static switches using thyristors).
4.5.5. In the case of the cabin and access doors, the measures for reducing the airborne
noise level at the source shall imply:
a) inserting cushioning products in the floating floor of the cabin to eliminate the impact
noise which occurs when it hits the interior frame or upper support elements as people enter
and exit the lift (applying a springy carpet on the floating floor would also help);
b) installing damping devices on the elevator doors.
4.5.6. The solutions chosen to limit airborne noise propagation shall ensure compliance
with the relationship
where:
 Lef  f    Lnec  f  ,
(dB)
(4.5.1)
 L nec  f   L s  f   L adm  f

(dB)
(4.5.2)
Ls  f
 - the noise level (dB) corresponding to the source taken into consideration;
L adm  f  - permissible noise level (dB) stipulated in the normative documents in
force, established depending on the types of activities carried out in the protected functional
units;
 Lef  f  - the actual airborne noise reduction obtained along the propagation paths.
4.5.7. The reduction  Lef  f  shall be determined by carrying out in situ acoustic
measurements in accordance with the provisions of SR 6161-1, SR 6161-1/C91 or by
62
calculation.
For guidance, Table 4.5.1 gives the reductions L f  corresponding to obstacles
which normally arise along the noise propagation paths, from the hoist chamber to the
protected functional units (see Figure 4.5.1).
The noise level reduction L f  , obtained when the noise is propagated along the
corridors located in front of the access doors and is transmitted through solid structural
walls, shall be determined in accordance with the provisions stipulated in Chapter 2 of this
regulation.
4.5.8. The following theoretical measures shall be taken into consideration to ensure
compliance with relationship (4.5.1) and achieve technical-economical optimisation:
a) choosing the location for the hoist chamber within the building carefully, to ensure that
it is as far away from the protected functional units as possible;
b) installing sound-absorbing treatments in the hoist chamber, corridors and, potentially,
the lift shaft;
c) creating, whenever possible, buffer spaces between the hoist chamber and the lift shaft.
Reductions  Lef  f 
Frequency (Hz)
Ite
m
No
1
2
3
4
Table 4.5.1
Obstacle
63
Overall
125
250
7
7
7
8
8
8
8
16
16
16
18
18
18
18
2
2
2
3
3
3
3
6
8
10
11
13
13
11
20 cm thick reinforced concrete
slabs with openings for passing
7
cables
Technical space with a height of
approximately 3 m, delimited
16
by the floor slabs as stipulated
in point 1
Attenuation over 10 linear
metres along the elevator shaft
2
(without acoustic treatment)
Access door to the lift shaft
6
500 1000 2000 4000
dB (A)
4.5.9. The level of structural noise produced during operation of the elevator electromechanical sub-assemblies installed in the hoist chamber shall be considered to remain
below the most stringent limits if the following requirement is met
 
Sef  f   Azv Czv 80 1 , (vibrations)
(4.5.3)
 
v
v
where: Az C z - equal physiological response curves for vibrations, defined in accordance
with SR 12025-2;
S ef  f  - maximum strength (vibration) level of the vibrations applied to the hoist
chamber floor.
4.5.10. The following theoretical measures shall be taken into consideration to ensure
compliance with relationship (4.5.3) in optimum technical-economical conditions:
a) ensuring the required stiffness of the hoist chamber floor;
b) installing the electro-mechanical sub-assemblies on correctly-dimensioned anti-vibration
63
support elements, in order to ensure minimum transmissibility;
c) elastic installation of the control panels using cushioning products.
4.5.11. The aerodynamic noise produced during movement of the elevator cabin shall be
controlled by limiting the travelling speed to 1.5 m/s.
For elevators moving at speeds higher than 1.5 m/s, certain sections of the elevator
with an area at least 3 times larger than the area of the horizontal cross-section of the cabin
and compensation air intake openings with a cross-section of at least 1 m2 must be provided
(in the top and bottom regions of the elevator shaft).
4.5.12.
When designing measures for reducing the noise level produced by elevator
installations in which flammable products are used, consideration shall be given to the
specific activities carried out within the premises, to ensure compliance with the
requirements stipulated in the regulations on fire safety in constructions.
Provisions for carrying out the works
4.5.13. During the implementation of noise protection measures in elevator systems, special
care shall be taken to ensure:
a) compliance with the dimensions stipulated in the design for the elastic suspensions of
the electro-mechanical sub-assemblies of the installation;
b) correct installation of the sound-absorbing treatments.
4.5.14. Any potential modifications to the design, with regard to the products or solutions for
installing elevator installations, shall only be implemented with the approval of the design
engineer.
4.6. Protection against structural noise produced by installations
This sub-chapter refers to the measures to be taken in order to reduce the noise level
produced by structural emission due to the vibrations and shocks induced by installations
(VAC, sanitary, thermal, electrical) and embedded equipment (elevators, escalators, moving
walkways, electric generator sets) in buildings. Anti-vibration isolation implies taking a
series of measures to significantly reduce the transmission of deterministic or random
shocks and vibrations along a radiating structural path, so that people are not affected and
the maximum permissible levels stipulated in the specialist standards are not exceeded.
Design elements
4.6.1. The main types of equipment which can transmit vibrations within structures are
presented, together with the performance requirements regarding the production and
transmission of shocks and vibrations, in Table 4.6.1.
64
Ite
m Systems
No
1
VAC
For lifting
2
and
transport
3
Power
supplying
4
Pipe
networks
5
Cold and
hot water
supply
systems
KEY
Requirement
Performance
s
requirements regarding
vibrations
a c d e
- physical integrity (shock
resistance)
Cold and hot air
- operation at the design
units
All types * * * * parameters
- retaining the position
Fans
- resistance to overturning
and pulling
Elevators
* * *
Escalators and Residential
- low transmissibility
moving
* * * * - low noise level
walkways
Public
- operational safety
Hoists
*
* *
Electric
- low transmissibility
generator sets
- low noise level
Public
*
* *
- mechanical resistance
Electric
- physical integrity
switchboards
Pipe networks
* * * * - low transmissibility
All types
- mechanical resistance
Pipes / Tubes
* * * *
- physical integrity
Water carrier
- mechanical resistance and
networks
* * * * stability
- physical and geometrical
Vertical boilers
All types
integrity
- maintaining connection
Pumps
* *
with the main structure
- resistance to fire
a – mechanical resistance and stability
c – hygiene, health, and environment
d – operational safety
e – noise protection
Equipment
Buildings
4.6.2. The noise and vibration protection provided shall achieve the following aims:
a) the building occupants can carry out their activities or rest without any disturbance
(achieving the parameters which ensure the ambient comfort level required for work, daily
rest, studying, etc.);
b) the building or parts of it do not undergo degradation that can
threaten its strength and total or partial stability;
c) to not affect the conditions for the safe operation of the building, as
well as its embedded systems and equipment.
4.6.3. Elastic anti-vibration systems must not allow transmission of
those vibrations produced by systems and equipment embedded in
structures, whose values exceed the limits stipulated in standards SR ISO Figure 4.6.1 Single degree
2631-1, SR12025-2.
of freedom system
4.6.4. The main characteristics of mechanical equipment modelled as single degree of
freedom systems, as shown in Figure 4.6.1, are the total mass/inertia of the equipment (m),
65
as well as the elasticity/stiffness (k) and the damping/dissipation (c) of the
supporting/hanging system.
The main parameters of free and forced harmonic vibrations shall be calculated as
follows:
a) natural pulsation:
p
k
g

m

(rad/s) (4.6.1)
b) natural frequency:
fn 
p
(Hz)
2
(4.6.2)
c) coefficient of transmissibility: T 
P0T

P0
1  4 22
1    4 
2 2
d) degree of vibration isolation: I  100  T ,
(%)
where the following notations were used:
g - gravitational acceleration
(m/s2)
 - static deformation of the elastic element
2
2
100 (%)
(4.6.3)
(4.6.4)
(m)
P0 - amplitude of the harmonic disturbance force (N)
P0 T - amplitude of the force transmitted to the foundation (N)


p

f
f n - relative pulsation/frequency (adjustment factor)
 - pulsation of the harmonic disturbance force
(rad/s)
f 
(Hz)

- frequency of the disturbance force
2
c

- fraction of critical damping
2 mk
Since, in most situations, the disturbances due to equipment and systems embedded in
buildings are produced by eccentric masses undergoing a stabilised rotating movement, the
characteristics of the harmonic disturbances shall be determined as follows:
n

e) excitation pulse:
(rad/s) (4.6.5)
30
P0  m0 r 2 , (N)
f) force amplitude:
(4.6.6)
where the following notations were used:
n - eccentric mass velocity (rotations/min)
m 0 r - total static moment of the eccentric masses (Kgm)
Resonant frequency - Hz
Static deformation - cm
Figure 4.6.2 Relationship between the static deformation δ and the resonant frequency fn
The relationship between the static deformation of the spring (elastic element) and
the natural (resonant) frequency of the system is represented graphically in Figure 4.6.2.
For equipment supported/suspended using various types of metallic springs with a
66
low damping level, the fraction of the critical damping can be considered to be very small (
  1 ) and the expression for the coefficient of transmissibility can be simplified as
follows:
T
1
100
1 2
(%)
(4.6.7)
4.6.5. Supporting/hanging systems must be designed so that the minimum degrees of antivibration isolation are achieved depending on the type of equipment embedded in the
building. Table 4.6.2 gives the minimum isolation degrees for various types of buildings,
depending on their intended use.
Table 4.6.2
Degree of isolation I (%)
Ite
Values required for churches, Values recommended for
m
Type of equipment
restaurants, warehouses, office
laundries, factories,
No
buildings, schools, hospitals,
technical basements,
radio studios
garages, mezzanine floors
1 Air conditioning units (monobloc)
90
70
2 Air treatment units
90
70
3 Centrifugal compressors
95
80
< 10 HP
85
70
4 Piston compressor
15–50 HP
90
75
50–150 HP
95
80
5 Heating and ventilation equipment
90
70
6 Cooling towers
90
70
7 Evaporative condensers
90
70
8 Pipe network
90
70
< 3 HP
85
70
9 Pumps
> 3 CP
95
80
4.6.6. When choosing the types of anti-vibration isolation systems and products, it shall be
made certain that the performance requirements for obtaining certain minimum degrees of
anti-vibration isolation are complied with. For this reason, Table 4.6.3 contains the
maximum degrees of isolation that are normally obtained as a function of the anti-vibration
isolation method and the excitation frequencies.
Table 4.6.3
Excitation frequency
350 500 650 800 1000 1200 1750 3600
(min-1)
Anti-vibration system
Natural frequency
Degree of isolation I (%)
(min-1)
109
88 95 97 98 99 Max. Max. Max.
Flexible isolation systems
133
80 92 96 97 98 98.5 Max. Max.
with metallic springs
188
60 84 91 94 96 97.5 99 Max.
Isolation systems made of
305
39 75 85 92 93 97 99
neoprene with high elasticity
Isolation systems made of
430
60 80 85 95 98
neoprene with low elasticity
Isolation products with two
502
67 79 91 97
shear layers
Isolation products with a
710
47 82 96
single shear layer
67
Isolation systems made of
flexible cork of standard
1415
73
density
4.6.7. The extent to which the vibrations produced by embedded equipment and systems
affect functional units in buildings shall be estimated on the basis of three criteria:
a) the response of the human subjects;
b) the potential damage caused to sensitive equipment within the building;
c) the severity of the vibrations of the embedded equipment/system.
95
Figure 4.6.3 and Table 4.6.4 give the acceptability criteria for the size of the
vibrations measured on the structure of the building near the source, or in the section of the
building where people or vibration-sensitive equipment are present.
If the permissible levels specified by the manufacturer are not available, the values specified
in the table and the curves shown in the figure shall be used.
Very severe
Curve
Velocit
y
Severe
Medium severity
R
M
S
vel
oci
ty
m/
s
R
M
S
vel
oci
ty
m/
s
Mild severity
Low severity
Low vibrations
Very low vibrations
Extremely low vibrations
Quasi-unperceivable
vibrations
Frequency - Hz
Figure 4.6.3 Vibration acceptability criteria
severity
Frequency - Hz
Figure 4.6.4
Assessment of vibration
Figure 4.6.4 shows the RMS velocity levels for which the severity of the vibrations
measured on the equipment, their supporting structure or the support elements can be
estimated. If measuring the displacement or RMS acceleration, the relationships between
these and velocity shall be
Y RMS 
v RMS


v RMS
2 f
(4.6.8)
68
Table 4.6.4
Requirements for human occupants
Period of the day
the entire period
the entire period
700-2200
Residents (good ambient standards)
2200-700
Operating theatres and critical work areas
the entire period
Requirements for equipment
Areas with computing equipment
Microscope < 100X; Laboratories equipped with robots
Microscope < 400X; Precision balances (including optical ones); Coordinate measuring
machines; Metrology laboratories; Optical comparators; Microelectronic equipment, class
A (*)
Micro-surgery; Eye surgery; Microscope > 400X; Isolated platform optical equipment;
Microelectronic equipment, class B (*)
Electronic microscope < 30000X; Micrometers; Magnetic resonance equipment;
Microelectronic equipment, class C (*)
Electronic microscope > 30000X; Mass spectometers; Cell implant equipment;
Microelectronic equipment, class D (*)
Non-isolated laser and optical research systems; Microelectronic equipment, class E (*)
Human occupants
Sales personnel
Clerks
Curve
J
I
H-I
G
F
H
F
E
D
C
B
A
(*) Class A: Inspection, sample testing, other equipment
Class B: Aligners, critical photo-lithography equipment with a line width > 3 m
Class C: Aligners, critical photo-lithography equipment with a line width of 1–3 m
Class D: Aligners, critical photo-lithography equipment with a line width of 0.5–1 m, electron beam systems
Class E: Aligners, critical photo-lithography equipment with a line width of 0.25–0.5 m, electron beam systems
a RMS   v RMS  2  fv RMS ,
where: Y RMS
,
v RMS
,
a RMS
(4.6.9)
are the RMS values for the displacement, velocity and
acceleration
f - centre frequency of 1/3 octave bands
4.6.8. To ensure a good degree of anti-vibration isolation of the embedded equipment and
systems, the natural frequency/pulsation of the system must be approximately 3–10 times
lower than the operating frequency/pulsation of the equipment (these limit values shall
correspond to a degree of isolation of approximately I= 87.5–99 %).
4.6.9. The isolation system and products, as well as the characteristics of the anti-vibration
elements shall be determined and chosen using the following algorithm:
a) the degree of isolation I shall be determined depending on the requirements stipulated;
b) the natural (resonance) frequency/pulsation fn/p shall be determined;
c) the static deformation of the anti-vibration isolation
system shall be determined with relationships (4.6.1) and
(4.6.2) or using the nomogram shown in Figure 4.6.2,
taking into account the geometric limitations and the
stability conditions for forcefully stabilised operation.
d) if using anti-vibration systems made of rubber or other
non-metallic products, the choosing and calculation
procedures specified in the manufacturers’ documentation
69
Figure 4.6.5 Isolated system with four
anti-vibration elements
shall be used;
e) if using pneumatic isolation systems, the choosing and calculation procedures specified
in the manufacturers’ documentation shall be used;
f) if using metallic springs to support/cushion the equipment, the stiffness coefficient of
the single element shall be determined as follows
k
G

mg
, (4.6.10)

where G  mg is the total weight of the embedded equipment or system.

4.6.10. For embedded equipment and systems that are supported/cushioned using four antivibration isolators (Figure 4.6.5), the supporting elements shall be chosen by taking into
consideration the weight distributed on each element (given by the position of the centre of
gravity C.G. within the horizontal plane). Therefore, the following calculation algorithm
should be used:
a) the forces absorbed by the four isolators shall be determined with relationships:
F1  G
a b
1  
l  h
(4.6.11)
 a  b 
F2  G 1  1  
 l  h 
F3  G
(4.6.12)
ab
l h
(4.6.13)
b a
F2  G 1  
h
l
(4.6.14)
b) the stiffness coefficients of the four elements (with the static deformation  determined
in accordance with Article 4.6.1.9 point c), the same for all found anti-vibration elements)
shall be determined:
ki 
Fi

i  1,4
(4.6.15)
c) for equipment with dimensional symmetry and symmetrical mass distribution, the
stiffness of the anti-vibration isolation elements shall be simplified as follows:
-symmetry with respect to a vertical axis ( a  0,5l b  0,5h ):
-symmetry with respect to a vertical plane ( b  0,5h ):
k2  k4 
k1  k 2  k 3  k 4 
k1  k 3 
G
4
G a
2 l
G  a
1  
2 
l
4.6.11. If a more complete (and more realistic) analysis of the equipment-structure
system is required, which takes into consideration the elasticity of the foundation
or overall structure, a calculation model with two degrees of freedom shall be
used, as shown in Figure 4.6.6. This calculation model should be used mainly for
equipment located on the top storeys of buildings, especially equipment installed
on the roof.
A two degree of freedom model can be used to obtain much more realistic
results even for equipment installed on the structure using flexible foundations. In
70
Figure 4.6.6
Two degree
of freedom
system
the given two degree of freedom model, the flexible foundation or structure is characterised
by the mass mf, the stiffness coefficient kf and the damping coefficient cf, whilst the antivibration isolation elements and equipment have the characteristics m (mass), k (stiffness
coefficient) and c (damping coefficient).
If the damping level is very low (e.g. structural damping, steel springs), the lagging 
between the excitation and the force transmitted to the structure shall be zero or , and the
natural pulsations/frequencies shall be calculated with the formulas

2
1  p f  k
p1  p 1 2 1
2  p  k f


 


 p2f  k
1 2 1
 p  k f
2


p2f 
  4 

p2 



2
1  p f  k
p2  p 1 2 1
2  p  k f

  p2f  k
  1 1
  p2  k
f
 

2


p2f 
  4 

p2 


(4.6.17)

 


2


f f2 
  4 

fn2 


(4.6.18)
f1  fn

2
1  f f  k
1
1
2  fn2  k f

f2  fn

2
1  f f  k 
1

1
2  fn2  k f 

 f f2  k
1 2 1
 fn  k f
(4.6.16)
2

 f f2  k 
f f2 
1 2 1   4 2  ,
fn 
 fn  k f 

(4.6.19)
where the following notations were used:
p
k
- natural pulsation of the system formed by the equipment and the antim
vibration isolation elements
kf
pf 
- natural pulsation of the foundation (flexible structure)
mf
fn 
ff 
p
1

2 2
pf
2

1
2
k
- natural frequency of the equipment
m
kf
m f - natural frequency of the foundation (flexible structure)
71
4.6.12. The coefficient of transmissibility for the disturbance force from the equipment to
the rigid structure of the building (via the foundation or the flexible structural components)
shall be calculated as a function of the characteristics of the equipment-foundation system
(natural pulsations/frequencies, elasticity) and the pulsation/frequency of the disturbance, as
follows:
T
P0T
100
100
P0
 2  k p2 2  k
1 2 1  2 2  


 p  k f p f p  k f
(%)
(4.6.20a)
P0T
100
100
P0
 f 2  k fn2 f 2  k
1 2 1  2 2  


 fn  k f f f fn  k f
(%)
(4.6.20b)
or
T
4.6.13. The rated (adimensional) amplitudes of the equipment and foundation displacements
shall be calculated with relationships
k 2
1  2
k f pf
k f2
1  2
kf f f
Y


P0  2  k 2  k  f 2  k f 2  k


1 2 1  2  
k 1 p2 1 k  p2   k




f
f 
f
 fn  k f f f  k f
Yf
1
1


P0   2  k  2  k
 f 2  k f 2  k ,


1 2 1  2  
k f 1 p2 1 k  p2   k




f
f 
f
 f n  k f f f  k f
(4.6.21)
(4.6.22)
where the following notations were used:
P0
- deformation of the elastic system supporting the equipment when the force P0
k
is applied under static conditions
P0
P
k f - foundation displacement when the force 0 is applied under static conditions
4.6.14. To design anti-vibration isolation systems that meet the performance requirements
and criteria stipulated in Article 4.6.5 and Article 4.6.6, the amplitude of the disturbances
generated by the embedded equipment and systems shall be determined experimentally or
by calculation. Since, in the majority of situations, the perturbations are generated by
eccentric masses undergoing a stabilised rotating movement at the speed n (rotations/min),
the harmonic force amplitude can be calculated using relationship (4.6.6), where the static
moment can be assessed with relationship
m0 r  0,0254
A
,
n
(Kgm)
72
(4.6.23)
where the constant A is given, for various classes of equipment with rotating elements, in
Table 4.6.5.
Table 4.6.5
Equipment (type of rotor)
A
Shafts and rotors of breaking machinery and agricultural machinery; individual engine
components; crankshafts in engines with at least six cylinders; mud pumps and
6.0
dredgers
Parts of technological processing machinery; reducers in marine turbines; centrifugal
drums; flywheels; pump rotors; machine tools; rotors in normal electric motors;
2.4
individual components of motors with special requirements
Steam and gas turbines; rotors in turbo generators and turbocharger compressors;
rotors in medium and large-size electrical machines with special requirements; rotors 1.0
in small-size electrical machines; turbine pumps
4.6.15. The normal (technological) values for imbalances (static moments of the eccentric
masses) occurring in helical fans and centrifugal blowers (in VAC systems) are given in
Table 4.6.6. The maximum imbalance values for this type of rotating machines can be up to
twice the values given in the table.
Table 4.6.6
Fans
Blowers
Diameter Imbalance Diameter Imbalance Diameter Imbalance Diameter Imbalance
(mm)
(gmm)
(mm)
(gmm)
(mm)
(gmm)
(mm)
(gmm)
205
610
216
<100
50.4
560
828.0
230
660
216
150
72.0
610
1000.8
255
710
288
180 205
93.6
660
1252.8
72
280
760
324
230 255
710
1504.8
108
305
915
432
280
760
1749.6
355
1065
720
305 355
815
2001.6
180
405
1220
1008
380
865
2253.6
108
455
1370
1080
405
324.0
915
2505.6
510
144
1525
1440
455
489.6
965
2750.4
560
180
510
662.4
1015
3002.4
4.6.16. Procedure for analysing the vibrations of embedded equipment - calculation
example for the anti-vibration isolation parameters (natural frequencies, coefficient of
transmissibility, degree of isolation) for a VAC unit activated by a centrifugal fan (blower)
with a rotor diameter of 965 mm, a rated speed of 300 rotations/min and a weight of
11 000 N, installed on a lightweight concrete slab with a 6 m span. The fan shall be located
1.8 m away from the end of the slab, on metallic springs with the static deformation equal to
25 mm. The slab shall be designed for a maximum variable load of 2 400 N/m2 (where the
actual variable load is equal to 1 450 N/m2), the deformation under the maximum variable
load being equal to 1/1 200 of the span of the slab.
73
4.6.16.1
Situation of a rigid slab (single degree of freedom system - Figure 4.6.1)
a) The natural pulsation and resonant frequency shall be calculated with relationships
(4.6.1) and (4.6.2):
9,81
 19,8091 (rad/s)
0,025
p 19,8091
fn 

 3,1527 (Hz)
2
2
p
g


b) The equivalent stiffness coefficient of the isolation system shall be calculated with
relationship (4.6.10):
k
G

11000
 440000
0,025
(N/m)

If the fan is supported on four springs, as shown in Figure 4.6.5, the individual
stiffness coefficients shall be determined with relationships (4.6.11)-(4.6.14).
c) The operating frequency and pulsation of the fan shall be calculated with relationship
(4.6.5):
n   300
 
 31,4159
(rad/s)
30
30
 31,4159
f 

 5 (Hz)
2
2
d) The adjustment factor of the fan shall be calculated as follows:
 31,4159
 
 1,5859
p 19,8091
e) The coefficient of transmissibility of the force to the rigid structure shall be calculated
with relationship (4.6.7):
T
f)
1
100  66
11,58592
(%)
The degree of isolation shall be calculated with relationship (4.6.4):
I  100  T  100  66  34
(%)
g) Since, in accordance with Table 4.6.2, the degree of isolation must be at least 90% (for
the most demanding applications), the adjustment factor Ω must have the minimum value:
1
100
100
 min  1 
 1
 1
 3,3166
Tmax
100  I min
100  90
100
There are three courses of action that can be taken to increase the adjustment factor
from 1.5859 to 3.3166:
10. Increasing the rated operating speed of the fan (which can increase the
disturbance force amplitude and the amplitude of the force transmitted to the structure of the
building);
20. Reducing the natural frequency/pulsation of the system by installing springs with
lower stiffness coefficients (which can increase static deformation until it reaches potentially
unacceptably high values);
30. Combining the actions specified in points 10 and 20.
74
4.6.16.2
Situation of a flexible slab (two degrees of freedom system - Figure 4.6.6)
a) The natural pulsation/frequency of the embedded equipment shall be calculated with
relationships (4.6.1) and (4.6.2):
g
9,81
p 19,8091

 19,8091 (rad/s) f n 

 3,1527 (Hz)

0,025
2
2
b) The equivalent stiffness coefficient of the isolation system shall be calculated with
relationship (4.6.10):
G 11000
k 
 440000 (N/m)
 0,025
If the fan is supported on four springs, as shown in Figure 4.6.5, the individual
stiffness coefficients shall be determined with relationships (4.6.11)-(4.6.14).
c) The operating frequency and pulsation of the fan shall be calculated with relationship
(4.6.5):
n   300
 31,4159
 
 31,4159

 5 (Hz)
(rad/s) f 
30
30
2
2
d) The amplitude of the inertial disturbance force shall be calculated with relationship
(4.6.6), the static imbalance moment considered to have the maximum possible value given
in Table 4.6.7:
m 0 r  2  3002 , 4  6004 ,8 (gmm)
 m 0 r  0,0060048 (Kgm)
P0  m0 r 2  0,0060048 31,41592  5,9265 (N)
p
Table 4.6.7
Load distributed on the slabs - design values (N/m2)
Distance between beams - 3 m
Type of platform
Known structure
Unknown structure
Heavy concrete (2400 Kg/m3)
Composite floor
Lightweight concrete (1600
Kg/m3)
Roof with a composite structure
Floor
Load
Variable Permanent
2400
4800
3200
2450
960
960-2150
e) The linearly distributed load pL on the equivalent beam of a slab with the distance
between beams D equal to 3 m (loaded with the actual variable load pvar and the permanent
load pper due to the natural weight of the slab) shall be calculated using the specific design
values given in Table 4.6.7:
p L  D  p var  p perm  (4.6.24)
p L  31450  2450   11700 (N/m)
f) The mass of the equivalent beam considered to be simply supported at its ends and
loaded with the linearly distributed load along its entire length L shall be calculated:
p L
m f  0,625 L
(4.6.25)
g
75
m f  0,625
11700  6
 4472,5 (kg)
9,81
g) The value EI shall be determined by considering that its static deformation (simply
supported at its ends) is produced by the maximum variable load pvarmax applied to the entire
slab (with the dimensions LxD):
5 p var max DL4
EI 
(4.6.26)
384

L
6

 0,005 (m)
1200 1200
5 2400  3  6 4
EI 
 2,43  10 7 (Nm2)
384 0,005

If the static deformation of the slab (floor or roof) is not specified in the building
specifications, the maximum permissible values given in Table 4.6.8 can be used.
Table 4.6.8
Deformation as a function of the span length
Load
Support
Variable
Permanent
Total
maximum
maximum
maximum
normal
Floor
L/360
L/240
L/1400-L/800
L/720
Roof
L/240
L/180
KC
h) The stiffness coefficient of the floor shall be calculated
with relationship
4,0
3 EIL
k f  KC 2
2
(4.6.27)
a L  a  ,
3,0
where a is the distance from the end of the beam where the
fan is installed, and the factor KC (as well as the factor equal
to 0.625 used to calculate the mass of the equivalent beam)
2,0
represents the correction applied due to the fact that, in
reality, a beam is not simply supported and the vertical
1,0
columns onto which the beams are fixed are also flexible.
The factor KC can have a minimum value equal to 1 (for a
0,1 0,3 0,5 0,7 0,9
a/L
simply supported beam) and shall reach its maximum value
for a beam embedded in the side columns, which are Figure 4.6.7 Variation of the factor
considered to be rigid. Figure 4.6.7 shows the maximum KC as a function of the position of the
value of the factor KC for a beam that is rigidly embedded at equipment on the equivalent beam
its ends, as a function of the ratio a/L. For most buildings
erected on a structural frame, the factor KC=1.267, therefore
the stiffness coefficient of the floor shall be calculated as follows:
3  2,43107  6
k f  1,267
 9,6964106 (N/m)
2
2
1,8 6 1,8
i) The natural pulsation and frequency of the floor shall be calculated with the following
relationships
kf
9,6964106
pf 

 46,5619 (rad/s)
mf
4472,5
ff 
pf
2

46,5619
 7,4106 (Hz)
2
76
j) The non-dimensional ratios of the stiffness coefficients and frequencies shall be
calculated as follows:
k
440000

 0,04538
k f 9,6964 10 6
2
 f 
 ff 
7,4106

 2,35056     5,52513   n   0,18099
f 
f n 3,1527
 fn 
 f
k) The natural frequencies of the system shall be calculated with relationships (4.6.18) and
(4.6.19):
2
ff
f1, 2  3,1527

1
1  5,525131  0,04538 
2
1  5,525131  0,045382  4  5,52513


f1  3,0697 (rad/s) f 2  7,6109 (rad/s)
l) The adjustment factor of the fan shall be calculated as follows:
 f 31,4159
f2
  
 1,5859 2  2,51508
p f n 19,8091
fn
m) The coefficient of transmissibility shall be calculated with relationship (4.6.20):
T
100
 138 (%)
1  2,515081  0,04538  0,18099  2,51508  0,04538
n) The displacement amplitudes of the fan and floor shall be calculated with relationships
(4.6.21) and (4.6.22):
Y
5,9265
1  0,04538  0,18099  2,51508
 10,967  10 6 (m)
440000 1  2,51508 1  0,04538  0,18099  2,51508   0,04538
5,9265
9,6964 106
Yf 
 0,84325106 (m)
1  2,515081  0,04538  0,18099  2,51508  0,04538
o) The root mean square values of the floor and fan speeds shall be calculated with
relationship (4.6.8):
Y
v RMS  YRMS  2f
 2  5 10,967  10 6  2,436  10  4 (m/s)
2
Yf
v fRMS  Y fRMS  2f
 2  5  0,84325  10  6  1,873  10 5 (m/s)
2
p) Interpretation of the results obtained:
10. Due to the fact that the fan operates at a rated frequency with a value between the
values of the two natural frequencies, the flexibility of the floor shall determine the system
to behave as an amplifier for the force transmitted to the structure of the building
(T>100 %). The coefficient of transmissibility can be reduced by reducing the natural
frequency of the floor (by increasing its flexibility or equivalent mass) or by increasing the
rated speed of the fan (potentially even tripling the speed so that the operating frequency is
approximately double the natural frequency f2);
20. From the point of view of vibration acceptability requirements, in accordance
with the criteria specified in Figure 4.6.3 and Table 4.6.4, the vibration of the floor shall be
between curves C and D, which shall enable any activities, including human rest. If taking
into account the requirements of highly sensitive optical and electronic equipment, the type
of floor vibrations that are going to occur near the fan taken into consideration must be
specified in advance in order to be able to determine the acceptability of these vibrations.
77
30. In accordance with Figure 4.6.4 and the calculated RMS speed values, it can be
considered that the vibration level is very low, both for the fan and the structure on which it
is installed.
4.6.17. The vibration isolation systems consist of the pedestal/structure of the embedded
equipment, the anti-vibration isolators and the supporting structure of the building. In
addition, the system must also include connecting elements (connections between pipes,
lines or electrical conductors), as well as limiting mechanisms necessary due to the
installation of inappropriate anti-vibration isolators or the presence of elements which limit
the isolating effect.
The mere presence of anti-vibration isolators does not guarantee that the equipment
will no longer send vibrations to the structure of the building: To be able to choose a
technically and economically efficient anti-vibration isolation system, design engineers must
have knowledge of the following elements:
a) the characteristics of the anti-vibration isolators: type, dimension, loading capacity,
elastic and rheological properties, permissible static and dynamic deformations,
identification system;
b) the dimensional and inertial properties of the equipment being isolated against
vibrations;
c) the anti-vibration isolation requirements of the actual application.
4.6.18. When choosing the anti-vibration isolation systems, individual elements and
products, one shall take into account their properties, the static and dynamic parameters of
the equipment being isolated against vibrations, as well as the global index that describes the
anti-vibration isolation (degree of anti-vibration isolation). Table 4.6.3 gives a few values
for the degrees of isolation that can be obtained depending on the isolators being used and
the working frequency ranges.
The anti-vibration isolation products, elements and systems most frequently used for
embedded equipment in buildings are:
a)
b)
c)
d)
e)
f)
g)
h)
steel springs;
elastomeric isolators;
pneumatic isolators;
fibreglass mats;
isolation pedestals;
flexible connectors;
floating floors;
seismic stoppers.
4.6.19. Steel springs are most frequently used for the vibration isolation of mechanicallyactivated equipment due to the fact that they are reliable, provide a high level of static
deformation (> 10 mm) and ensure good anti-vibration isolation.
Figure 4.6.8
Figure 4.6.9
78
Cylindrical helical steel spring
Spring system with a displacement limiting
function
The free steel spring assembly is fitted at both ends with metallic plates, neoprene
mats and an adjustment and retaining screw, as shown in Figure 4.6.8. The steel springs
shall be chosen by making sure that the ratio between the diameter and the operating height
(height under the static load) is 0.8–1.0. The springs must be designed to ensure that the
horizontal stiffness is at least equal to the horizontal one (to ensure stability during
operation) and the deformation is at least 50% over the rated load. The neoprene mat
(approximately 6 mm thick) shall be used to reduce the transmission of high-frequency
vibrations to the structure of the building, as well as to install the isolator onto concrete slabs
without having to use any bolts or other retaining systems.
Steel springs with a displacement limiting function are used if the equipment is
temporarily moved or when the isolator is being installed (Figure 4.6.9) and the spring must
be blocked. The categories of embedded equipment which require such anti-vibration
isolation systems are:
a) equipment with large mass variations (boilers, refrigeration equipment);
b) outdoor equipment (e.g. cooling towers), in order to prevent excessive
displacement due to the wind.
After the displacement-limiting springs have
been installed, the adjustment elements (nuts, screws)
shall be removed or shortened to ensure the necessary
distance which allows the spring to absorb the forces
without changing height. If this type of isolator is used
for outdoor equipment with large lateral displacement
movements due to the wind, it shall be made certain
Figure 4.6.10
Figure 4.6.11
that the isolator is not blocked due to direct contact
between the upper plate and the displacement-limiting Encased steel spring Hanging spring
bolts.
The advantage of encased metallic helical spring isolators (Figure 4.6.10) is that
they have a smaller size to install and dynamic stability during operation. This type of
isolator is not used very often since the casing (which is lined with neoprene on the inside)
tends to block the spring in the presence of large lateral loads and, also, does not allow for
an easy inspection in the event of a malfunction.
Metallic hanging spring isolators are used for the anti-vibration isolation of the
pipes, ducts and small components of systems and equipment that are suspended from the
ceiling. This type of isolator can be made up of metallic springs with a neoprene layer or,
even better, a combination of metallic springs and neoprene isolators. Regardless of their
design, it is important that the hole located at the top of the casing is large enough to enable
rotation of the hanging bar at an angle of at least 250 before the spring comes in contact with
the casing; direct contact between the metallic hanging bar and the casing will block the
anti-vibration isolator.
79
4.6.20. Due to their low manufacturing costs, elastomeric anti-vibration isolators of
various geometric shapes obtained by moulding or in the form of profiled mats are widely
used to manufacture supporting/hanging systems used for mechanically-activated
equipment, as well as other types of machines or
components. The products used to manufacture this
type of isolators are: neoprene, butyl, silicone,
polyurethane, natural and synthetic rubber. Neoprene
is the most used elastomer, due to its properties
(resistance to acid and alkaline media, as well as to
mineral and synthetic oils).
Figure 4.6.12
Figure 4.6.13
Elastomeric isolators shall be used if the level Molded neoprene Molded neoprene
of static and dynamic deformation required is not too
isolator
mat
high. Normally, the permissible static deformations are
up to 8 mm and cannot exceed 12–13 mm.
Elastomeric isolators are primarily used for the anti-vibration isolation of lightweight
and low-power equipment or equipment installed in building basements. Isolators obtained
by moulding (molded isolators) can have various geometric shapes, of which the most
frequently used are cylindrical, tapered, parallelepipedal, hyperbolic, annular and spherical
shapes (Figure 4.6.12 shows an isolator equipped with a supporting/retaining foot and an
upper plate for installation onto the equipment). Normally, molded elastomers have a
hardness between 300Sh and 700Sh, which can be recognised using the (international) colour
code: black for 300Sh, green for 400Sh, red for 500Sh, white for 600Sh and yellow for 700Sh.
To increase reliability, the isolation properties and stability during use under dynamic
conditions, molded elastomeric isolators can be equipped with inserts of various materials
and structures, metallic plates and retaining bolts/screws, or various assemblies containing
several such elements can be installed, depending on the design requirements.
Molded mats made of elastomers (Figure 4.6.13) with a hardness of 30-600Sh,
whether with a single layer or two layers with an insert between them, shall be used to
isolate high frequencies, regardless of whether or not they are fixed to the structure of the
building. They are frequently used as a seating
support for steel spring isolators and, sometimes,
in the foundations of certain mechanical
equipment.
Hanging isolators made of elastomers
have a similar design to steel spring isolators and
are sometimes used in combination with these.
Figure 4.6.14
Figure 4.6.15
Pneumatic
Fibreglass
4.6.21. Pneumatic isolators (air cushion springs)
isolator
isolator
are enclosed tubes (grommets) of a cylindrical,
toroidal shape (Figure 4.6.14) or even a prismatic
shape, made of rubber that can withstand rated pressures of 700 kPa and ensures the static
and dynamic stability of the equipment. These are frequently used in the structure of antivibration systems with resonant frequencies of 0.5–1.5 Hz (depending on their shape and on
the pressure) and equivalent static deformations of 150–180 mm, and have the advantage of
being able to bear a wide range of loads by varying the air pressure inside the grommet.
Pneumatic isolators are equipped with an air supply system and valves for
controlling and adjusting the height and pressure inside the grommet in order to ensure the
necessary loads and compensate for the temperature variations and external forces.
4.6.22. Fibreglass isolators and the mats made of high-density, inorganic, inert, compressed
molded fibreglass are covered with an elastomer layer to make them water resistant.
80
Fibreglass isolators (Figure 4.6.15) are 25–100 mm thick, can have a static
deformation of 5–25 mm and can bear loads of 10–7 500 Kg.
Fibreglass mats are used to isolate pumps, crystallisers, cooling towers and other
similar equipment, are highly efficient in reducing the shocks induced by various types of
machines and are used as a support for floating floors or the additional foundations of heavy
equipment.
Engine shaft
Fan shaft
Figure 4.6.16 Structural pedestal
for fan actuation
Figure 4.6.17
Metallic frames
Figure 4.6.18 Metallic pedestal
with embedded concrete
4.6.23. Isolation pedestals are the best isolation solution, from a technical point of view, for
equipment activated by various types of motors via mechanical transmission. Due to their
high torsional and bending stiffness, these systems maintain the alignment of the equipment
with the drive motor, increase the reliability of belt transmissions and provide the equipment
with a high level of isolation.
The pedestals consist of metallic structures (beams, frames), sometimes filled with
concrete, and are installed on the structure of the building using individual anti-vibration
isolators.
The design of the isolator platforms is just as important as the design of the actual
isolators. The design must take into consideration a series of issues, such as:
a)
the bending and torsional strength under the action of the distributed dead load and
of the equipment, as well as the stress placed by the motor on the transmission elements or
the equipment;
b)
platform resonance: the long or heavier pedestal components tend to vibrate at lower
frequencies, which increases the the forces transmitted to the anti-vibration isolators.
Structural pedestals (Figure 4.6.16) can be installed on metallic spring vibration
isolators or elastomeric isolators, must keep the alignment of the components of the
equipment and must bear the dynamic service
Anti-vibration elements
with a porous structure
stresses, especially those due to transient
Water and wind
conditions (starting, stopping), without any
protection
additional position-keeping devices.
element
Flexible closing
element
81
Figure 4.6.19 Structural pedestal for fan actuation
Structural pedestals are manufactured by welding together large steel profiles (T, L,
I, U) (up to 350 mm providing that the height does not exceed 1/10 of the length), have a
rectangular shape and can be used for all types of embedded equipment. For split case
pumps, support elements for the intake and discharge elbows can also be installed.
Metallic frames (Figure 4.6.17) are used to support the equipment which does not
require a unitary pedestal or where the isolators are outside of the vertical projection of the
equipment and the frames act as a cradle. Beams with heights between 100 mm and 300 mm
are used in practice (unless stipulated otherwise), providing that these heights are not lower
than 1/10 of the beam span.
Metallic pedestals with embedded concrete shall be used for the anti-vibration
isolation of pumps, high pressure fans or equipment with a high imbalance level of their
rotating components with a low rated speed (as shown in Figure 4.6.18). These isolation
systems are characterised by a uniform weight distribution on the individual anti-vibration
isolators, a drop in the centre of gravity of the equipment (which increases static and
dynamic stability) and an increase in the level of isolation at low frequencies. The metallic
pedestal shall be delivered with longitudinal reinforcement bars (girders) and transversal
reinforcement bars (ribs) installed every 150 mm apart, and the concrete shall be poured at
the place of installation of the pedestal.
Pedestals with limiting devices are used to install equipment on the roof of a
building (as shown in Figure 4.6.19), such as air supply units, refrigeration equipment and
discharge fans. These pedestals must meet strict vibration isolation requirements (due to the
higher flexibility of the roof) and additional requirements which include the wind, rain and
frost insulation of the individual isolators, as well as stability under aerodynamic actions due
to the large exposed surfaces.
4.6.24. Designing a vibration isolation system consists of choosing and installing the antivibration isolators and their supporting pedestals correctly, as well as connecting the pipes,
ducts and electrical conductors using flexible connectors which prevent the transmission of
high vibration levels from the equipment to the structure of the building. Therefore, these
connections shall be made in accordance with the following requirements:
a) electrical connections must be made using flexible conductors, which must be longer
and free so that the free movement of the equipment is not hindered;
b) the pipes shall be connected to the vibration isolation equipment using flexible hoses or
Impregnated
wire braided reinforced hoses; if this is not possible, the
braiding
pipes shall be isolated against vibrations using hanging spring
isolators or elastomeric isolators installed no further than 9 m
away. Both methods for the vibration insulation of pipes shall
not be applied simultaneously.
Displacement
c) the ducts shall be connected to the fans or plenum
limiting device
chambers using specially treated (impregnated) braiding with a
minimum length equal to twice the distance between the duct Figure 4.6.20 Connecting air ducts
and the fan/plenum chamber (Figure 4.6.20). Devices with
with flexible connectors
metallic springs for limiting excessive displacement shall be
installed at the places where very high pressure (axial,
centrifugal) fans are connected to the ducts. If specially-treated
braiding cannot be used, the ducts shall be isolated against
vibrations using hanging isolators installed no more than 15 m
away from the opening to which the duct is connected (Figure
4.6.21). These isolators should be used for all ducts in which
static pressure is higher than 500 kPa, as well as in ducts with
large cross-sections and an air speed of more than 10 m/s. Both
methods for the vibration insulation of ducts shall not be
Figure 4.6.21 Duct installed on
82
the ceiling using hanging
isolators
applied simultaneously.
Flexible hoses and pipes made of butyl rubber or pipes with wire braiding are
frequently used along the pipes to reduce vibration and, although they do not provide full
protection against the transmission of noise and vibrations along the ducts, they allow the
vibration-isolated equipment to move relatively freely compared to the pipes connected to
them. In addition, the flexible tubes also compensate minor misalignments and prevent
deformation of the pipe under the load.
The following recommendations must be taken into consideration when using
flexible hoses:
a) their efficiency as vibration isolators decreases as the fluid pressure increases;
b) the length of the hose is usually 6–10 times its diameter (Figure 4.6.22) and does not
exceed 1m (excessive length tends to distort the hose)
c) flexible hoses can be protected against elongation using cables, as shown in Figure
4.6.22.b.
Wire braided reinforced
hoses (Figure 4.6.23) can have
various ways of fixing onto the
a
a
pipes (a-threaded, b-flanged) and,
although they are not as efficient as
butyl hoses as far as anti-vibration
isolation is concerned, they are used
when the fluid temperature exceeds
1000C or the pressure exceeds the
b
b
values recommended for rubber
Figure 4.6.22 Flexible hoses
Figure 4.6.23 Wire
hoses.
braided hoses
As a general rule for
installing flexible rubber tubes (whether or not reinforced with wire braiding), the horizontal
operating position, parallel to the rotation axis of the mobile parts of the equipment, must be
complied with as much as possible, so that most deformations occur in a transversal
direction.
Figure 4.6.24
Rubber joint
Figure 4.6.24 shows a rubber joint which, although it is too short to act as an
efficient anti-vibration isolator, is used because it enables axial, transversal and angular
elongation and contraction.
4.6.25. Floating floors shall be used when, under a room housing various mechanical
equipment, or under kitchens, workshops, sports halls (in general, rooms for which the noise
and vibration level requirements are less exigent) there are spaces which require lower levels
of noise and vibrations (offices, conference halls, theatres, libraries, recording studios, etc.).
Figure 4.6.25 shows two systems of platforms or floating floors consisting of a
reinforced concrete slab mounted on elastomeric (rubber mat) isolators, fibreglass isolators
or metallic spring isolators. One of the main requirements is that the slab can move freely
along the entire perimeter and near the columns and foundations/platforms of the equipment;
therefore, a continuous isolating border shall be installed at the periphery of the slab; this
border shall have a thickness of 25 mm and shall be wide enough to reach to the structural
83
slab of the building (floor, ceiling). After casting the slab, the peripheral gap shall be filled
with hemp.
Floating floor
Plastic sheet
Casting
moulds
Caulking
Insulating
material
Connecting plates
Casting moulds
Floor in a
raised
position
Cementing
Antivibration
element
Perimetral
insulation
a
Plastic
Caulking
Reinforcement
Pedestal
Gap (air)
Floor in a
lowered
position
Isolator
Isolation casing of the
lifting element
b
Figure 4.6.25 Vibration isolation systems with floating floors
Figure 4.6.26 shows a lifting system which poses the
Caulking
advantage that the platform is cast in a lower position and, after
Perimetral insulation
the concrete has hardened, it is lifted to the normal operating
Isolation of the lifting
position using the screws in the vibration isolators.
If gyms, dance halls, basketball courts, sports halls or plate
Cementing
noise rooms which do not contain mechanically-activated
machinery are located above critical spaces with strict noise
and vibration requirements, these can also be insulated using
wooden floating platforms as shown in Figure 4.6.27.
The
main
purpose
for
installing
floating
floors/platforms is to reduce the structural noise and vibrations
Figure 4.6.26 Floating
transmitted to the rooms below. However, floating
lifting platform
Protection surface
floors can, potentially, only act as support bases for
Stratified wood element (2 layers)
lightweight machines of low power; heavy or high
Wooden support
power machinery must have their own foundation
Sound-insulating
systems isolated from the building structure and the
fibreglass
Anti-vibration
floating floors in the room where they are located (as
support
shown in Figure 4.6.25.b)
4.6.26. The pipe system connected to noise
and vibration sources such as pumps, water pressure
tanks or other machines with rotating parts must be
84
Figure 4.6.27 Wooden
floating platform
flexible in order to:
a) reduce and prevent vibrations (which are induced by pumps, water pressure tanks and
other equipment that they are connected to, or which are due to turbulent water flow) so that
they are not transmitted to the structure of the building;
b) avoid compromising the vibration isolation;
c) enable movement of the equipment and elongation or contraction of the pipes (due to
temperature variations) without applying any unacceptable stresses.
The following minimum requirements must be complied with in order to ensure the
flexibility of the pipe system:
a) whenever possible, flexible connectors shall be used between the pipes and the
equipment being isolated against vibrations;
b) if using hanging isolators (Figure 4.6.28) or floor-mounted isolators to isolate the pipes,
the static deformations of these isolators must be equal to the static deformations of the
equipment for a distance of at least 9 m;
c) the pipes must be isolated inside the room containing mechanical machinery or at a
maximum distance of 15 m away from the connection to the equipment;
d) the maximum static deformation of hanging isolators must not exceed 50 mm;
e) the static deformation of the other isolators after the 9 m distance from the connection
with the equipment must not exceed 20 mm;
f) the first two isolators closest to the equipment must be of the hanging type and must be
prestressed (to prevent the transfer of any stresses to the equipment);
g) hanging isolators shall be used for pipes with diameters larger than 200 mm;
h) if using flexible connectors, the first hanging element after the connection must be rigid,
and all the other elements must be flexible hanging isolators;
i) hanging isolators shall be used for pipes with a minimum diameter of 50 mm and pipes
suspended under noise-sensitive rooms.
a
b
Figure 4.6.28 Hanging isolators for pipes
85
Figure 4.6.29 Isolation systems for vertical pipes
Vertical pipes must be fitted with supports and guide systems which enable the axial
displacement of the connections and elbows due to compression or stretching induced by
temperature variations. These retaining and guide systems (clips, clamps, brackets) are fixed
rigidly to the structure of the building.
Vertical pipes shall be installed in non-critical areas adjacent to the lift pit, staircases
and other similar spaces to ensure that areas with strict noise and vibration requirements are
not affected. If this is not possible, the elements supporting the vertical pipes must be
isolated against vibrations. Depending on the degree of vibration isolation required, the
configurations shown in Figure 4.6.29 can be used, where the supports are seated on a
rubber mat (version a) or the isolation is ensured by steel springs (version b).
Provisions for carrying out the works
4.6.27. When installing mechanically-activated equipment, special care shall be taken to:
a) comply with the dimensions of the foundation block, as well as the dimensions and
quality required for anti-vibration isolation products or vibration isolators;
b) comply with the types of equipment stipulated in the design;
c) comply with the types of products stipulated for elastic joints.
4.6.28. When installing channels, ducts and pipes, special care shall be taken to:
a) comply with the details for their elastic fixing onto rigid structural elements;
b) comply with the details for passing through walls and slabs.
4.6.29. When installing sanitary installations, special care shall be taken to:
a) insert cushioning products between the pipes and their retaining clips;
b) secure the retaining clips using dowel pins insulated with dampers;
c) fix the ducts and pipes onto the ceiling using hanging isolators;
d) install sanitary fixtures using cushioning products;
e) apply elastic sealant at the place where the pipes pass through walls and floor slabs;
f) sound-insulating masks must be installed elastically on the structure of the building
(floor, ceiling, walls).
4.6.30. Any potential modifications to the design, with regard to the products or solutions for
installing the equipment, shall only be implemented with the approval of the design
engineer.
86
4.6.31. When carrying out installation works for elevator systems, the dimensions stipulated
in the design shall be ensured for the design type, quality and dimensions of the elastic
suspensions of electro-mechanical sub-assemblies.
Provisions for carrying out repairs in existing situations
4.6.32. The most frequent issues arising in relation to structural noise and vibrations are due
to:
a) operation of the equipment with excessive vibration levels (due to imbalances);
b) absence of anti-vibration isolators;
c) the use of inappropriate or incorrectly installed anti-vibration isolators;
d) rigid connection of the pipes or obstruction of the vibration isolators or platforms of the
equipment;
e) the flexibility of the slab;
f) the resonance of the equipment, isolation system or building structure.
4.6.33. In most situations, anti-vibration isolators are the cause of all problems relating to
high vibration levels and, therefore, structural noise. These issues relating to anti-vibration
isolators can only be assessed and remedied if the following are taken into account:
a) the equipment (or its pedestal) must be able to move freely without obstructing the
isolators;
b) for floor-mounted equipment, it must be checked that there are no metallic parts
between the pedestal and the floor that can short-circuit the isolation system;
c) for equipment suspended from the ceiling, the supporting rod must not touch the
isolator casing;
d) the static deformation of the isolator must be the one specified/required; a smaller
deformation (insufficient loading) will increase the natural frequency of the equipment and
have negative effects on its operation under dynamic conditions; overloading the equipment
would not be a problem as long as the isolator is not obstructed (e.g. “coil on coil” for
metallic springs) and the maximum permissible load is not exceeded.
4.6.34. To remedy situations which are deficient from the point of view of anti-vibration
isolation, investigations of the entire equipment-vibration isolators-structure system shall be
carried out, which must include:
a) measurements of the imbalances of equipment components which perform rotating
movements or alternative rectilinear displacements; for the normal limits of these
imbalances, one shall take into consideration the values given in Tables 4.6.5 and 4.6.6 and
the calculation relationship (4.6.23);
b) carrying out measurements of the vibration level on the vibration-generating equipment;
the severity of the vibration shall be estimated using the values given in Figure 4.6.4;
c) carrying out measurements of the vibration level on the structure of the building on
which the equipment is located; the acceptability of the vibrations shall be determined using
the values given in Figure 4.6.3 and Table 4.6.4, depending on the intended use of the
structure and the vibration isolation requirements;
d) examining the equipment vibrations generated by the system components (supporting
elements, bearings, transmission belts, etc.);
e) examining the installation parameters of the equipment (alignment, location of the antivibration isolators).
4.6.35. There are usually no problems in determining the source of vibrations, since the
87
vibration levels are significantly higher than the perception level and can be noticed.
A simple way of determining the source is to stop and start the individual
components of the equipment until the vibration is eliminated. Since problems can be caused
by several components of the system or by the interaction between two or more systems,
cross-checks should be carried out on sub-systems of the equipment.
4.6.36. The noise produced shall be transmitted structurally (by vibrations), if:
a) the vibration is perceivable (in this situation, the possibility that the lightweight panels
or even the ceiling could be excited by airborne noise should, however, be taken into
consideration);
b) the vibration is not perceivable and the difference in the level of noise intensity,
measured on the linear scales A and C, is higher than 6 dB, or if the slope of the 1/1 octave
band frequency/intensity curve is higher than 5–6 dB/octave for low frequencies;
c) the affected area is removed from the source equipment, there are no problems relating
to noise and vibrations in the intermediate spaces and the noise does not seem to come from
the pipe system, ducts, installations or speakers.
4.7. Household waste disposal systems
This sub-chapter refers to the measures that need to be taken in order to reduce the
noise level produced inside a functional unit due to the use of household waste disposal
systems.
4.7.1. Household waste disposal systems consist of vertical tubes that have collection
hatches on each storey of the building. At the base, these tubes spill into bins or incineration
installations.
Household waste disposal systems can be installed inside or outside of the building
(fixed to various elements of the building: walls, balcony parapets, etc.).
Interior waste disposal systems should not be installed on walls shared with
protected rooms inside functional units (bedrooms, patient wards, etc.). The best solution
from an acoustic point of view is to install these systems near the lift pit.
4.7.2. The walls of the household waste disposal tubes must have a double structure and be
provided with a sound-absorbing material on the inside (e.g. mineral wools with a density of
at least 90 kg/m3).
4.7.3. Access doors to rooms where household waste disposal tubes are located shall be
made of solid wood and shall be sealed around the edges.
4.7.4. Protected spaces shall be provided for handling the waste bins, both in existing
buildings and in newly designed buildings, and suitable measures shall be taken to eliminate
any kind of discomfort (relating to air purity, hygiene, acoustic protection, etc.).
88
ANNEX 1
RECOMMENDATIONS FOR THE DYNAMIC AND ACOUSTIC
CHARACTERISATION OF EQUIPMENT LOCATED IN
INDUSTRIAL HALLS, AIMED TO ENABLE THE DRAWING UP
OF TECHNICAL DESIGNS
A1.1. General aspects
A1.1.1.
These recommendations refer to the way in which the dynamic and
acoustic characteristics should be included in the specifications and internal rules for
equipment and machinery.
A1.1.2.
In accordance with point A1.1.1, the specifications and internal rules
must provide details to enable acoustic calculation of the industrial facility taken into
consideration when drawing up the technical design.
The primary aim of the acoustic calculation is to highlight those situations in which
the permissible acoustic limits stipulated by law could be exceeded.
A1.2. Principles for including the dynamic and acoustic characteristics in the
specifications and internal rules.
A1.2.1.
The chapter regarding the main structural, functional and dimensional
characteristics shall describe in detail the supporting elements, to enable the most accurate
dynamic modelling of the “machine (equipment) - supporting element”.
A1.2.2.
The chapter dedicated to the special requirements that the machine or
equipment and its parts and sub-assemblies must comply with shall specify the following
data obtained following technico-economical optimisation of the measures for reducing
noise and vibrations, as well as the data relating to keeping the lowest price possible;
a) The maximum permissible noise level;
b) The acoustic directivity characteristic of the equipment;
c) The type of wave developed;
d) The maximum permissible vibration level in the characteristic points of the
machine or equipment (the vibrations shall be considered in the three-axial system);
e) The maximum permissible level of relative vibration between the machine or
equipment and the material to be processed (when applicable);
f) The maximum permissible level of vibrations on the supporting elements.
Notes:
If the maximum noise level emitted by a machine or piece of equipment,
determined under standard conditions, does not exceed 70 dB(A), it shall not be necessary to
specify the characteristics mentioned at points “b” and “c”.
A1.2.3.
The chapter regarding the requirements for protection and decorative
coatings, paint coatings, etc. shall specify the products that could potentially replace the
initial products during the repair or rearrangement process, so that they do not modify the
dynamic and acoustic characteristics of the machine or equipment, or some of its subassemblies.
A1.2.4.
The chapter listing all the tests and inspections to be carried out during
acceptance of batch manufactured products, in the order in which they should be carried out,
shall also specify the necessary tests for determining the data specified in point A1.2.2.
89
A1.2.5.
The chapter regarding the conditions in which the tests are carried out,
the duration of the tests, the testing methods, the instruments, devices and testers needed for
each individual test, the permissible deviations from the nominal values and the tolerances
for the characteristics shall also include all necessary provisions in order to carry out tests
for determining the data specified in point A1.2.2.
Note:
If, at the time the specifications or internal rules are drawn up there are no official
technical provisions available to regulate the measurement of the noise and vibration level
for certain categories of machines or equipment, the testing methodology shall be described
in detail in the specifications or internal rules.
A1.2.6.
The chapter regarding the structure of the machine or equipment and
specifying the accessories that must be delivered together with it (normal delivery package),
as well as the accessories that are to be delivered upon special order only (optional delivery
package), shall also list the acoustic protection accessories, specifying their acoustic
performance.
A1.2.7.
The chapter regarding the installation and usage conditions for the
new products, the operating guarantee periods and the period required between repairs shall
also include standard details which ensure the lowest noise and vibration levels possible
during operation.
A1.2.8.
The chapter including lubrication, packaging, marking, storage,
transport and air-conditioning requirements, etc. shall also specify the negative acoustic
effects that could occur due to poor maintenance of the product.
A1.2.9.
The chapter regarding health and safety at work shall specify the
vibration levels permitted during contact between the equipment and the service personnel.
A1.2.10. The chapter regarding the guide price for each individual product shall
also specify the prices for each of these products.
90
ANNEX 2
SOUNDPROOF CASINGS
The casings are spatial elements designed to:
- protect equipment against various mechanical actions or toxic emissions
resulting from technological processes;
- prevent potential accidents that could occur due to direct contact with the
equipment;
- attenuate the noise produced by equipment.
Classification
1. Depending on their access possibilities, casings can be grouped into:
 Non-accessible casings;

Accessible casings
2. Depending on their ventilation needs, casings can be grouped into:
91
 Non-ventilated casings;
 Ventilated casings.
3. Depending on their installation possibilities, casings can be grouped into:

Fixed casings;

Dismountable casings:
- with a mobile ceiling:
- bell-shaped:
92
- with one or more mobile walls;
- with certain parts of the casing (elements or subassemblies) being of the sliding type:
Description
Casings can be metal-clad or can have slits.
They can be made of traditional building products (fired clay masonry elements,
concrete, autoclaved cellular concrete) or sandwich panels (which are made of lightweight
panels and have a sound-absorbing core).
93
ANNEX 3
METHOD FOR CALCULATING THE ADDITIONAL LEVEL
REDUCTION “ΔLva” CORRESPONDING TO THE
APPLICATION OF VIBRATION DAMPING TREATMENTS ON
THIN BOARDS
This method shall be used when vibration damping treatments consisting of thin
boards made of plastic, metal sheet, etc. are applied to the support panel using layers of low
stiffness products, such as: felt, spongy polyurethane, polystyrene, low hardness rubber (40°
- 60° Shore) etc.
The curve of the level reduction “ΔLva” as a function of the frequency shall be
determined as follows:
a) The resonant frequency of the “layer-support (thin board) - vibration damping
treatment” assembly shall be calculated with relationship:
 1
1 

f r  500 k  
 m1 m2 
(Hz)
where:
m1 - mass per unit area of the support layer (thin boards) (kg/m2);
m1 - mass per unit area of the coating layer of the vibration damping treatment
(kg/m2);
k - dynamic stiffness of the separating layer of the vibration damping treatment (107
N/m3).
b) Value ΔLva = 0 shall be adopted from the start of the usable frequency range
(100 Hz) until the resonant frequency “fr” is reached;
c) From the resonant frequency “fr” to the end of the usable frequency range
(3 150 Hz), the level reduction corresponding to a certain frequency “f” shall be calculated
with relationship:
Lva  40 lg
f
fr
(dB)
Table A.3.1. presents a few dynamic stiffness values for some products used as a
separating layer in vibration damping treatments applied to thin boards.
Table A.3.1.
Ite
Dynamic
Layer thickness
m
Name of the product
stiffness “k”
(mm)
No
(107 N/m3)
Boards made of cold-hardened cellular
1
10
1.5
polystyrene
2 Expanded cork boards
20
6.5
3 Woodfibre boards
25
9.0
10
2.7
4 Felt
15
1.8
20
1.35
94
Example of a method for calculating the level reduction “ΔLva”
Structure:
- steel sheet with a thickness of 1 mm;
- felt with a thickness of 15 mm;
- bituminous sheet with added rubber
a) Calculation of the resonant frequency of the structure:
 1
1 

f r  500 k 

m
m
2 
 1
where:
m1 - mass per unit area of the metal sheet layer (7.8 kg/m2);
m1 - mass per unit area of the bituminous sheet layer (5.1 kg/m2);
k - dynamic stiffness of the felt layer (1.8 x 107 N/m3) - in accordance with the table.
1 
 1
f r  500 1,8
   381 Hz
 7,8 5,1 
b) Curve “ΔLva” shall be plotted from points “b” and “c” stipulated in ANNEX 4
and is shown in Figure A.3.1 below.
experimenta
l
calculation
95
ANNEX 4
DETERMINATION OF THE ATTENUATION INDEX CURVE “RI(F)”
FOR SINGLE AND DOUBLE-LAYERED HOMOGENEOUS
CLOSING ELEMENTS
As defined in this regulation, the closing element shall be homogeneous when it has the
same structure in the yOz plane.
Figure A.4.1
A few simplified methods used to calculate the curve Ri(f) for homogeneous closing
elements are presented below:
I - single-layered
II - double-layered
I.
Determination of the curve “Ri(f)” for single-layered homogeneous elements
Figure A.4.2
96
Note:
The building element shown in Figure a), which is made of a single product with a
thickness “d”, and the building element shown in Figure b), which is made of
overlapping layers of products with comparable bending stiffness, shall also be
regarded as single-layered elements. In general, case b) refers to building
elements made of a single main product with finished surfaces.
The acoustic attenuation index curve “Ri(f)” shall be determined as follows:
The mass per unit of surface area of the building element, “m”, shall be determined, in
kg/m²;
The frequency range for the congruence area porch (fB – fC) shall be calculated using the
relationships given in Table A.4.1. The same table shall be used to determined the
attenuation index in the congruence area “RB = RC”, depending on the material that the
building element is made of;
Product
R B = RC
dB
Plain concrete, reinforced
concrete
Masonry made of fired clay
elements
38
37
Autoclaved cellular concrete
29
Plaster
25
Glass
27
Wood products
19
fB
Hz
19000
m
17000
m
6700
m
5000
m
5300
m
2100
m
Table A.4.1
fC
Hz
85000
m
77000
m
43000
m
38000
m
53000
m
13600
m
Curve “Ri(f)” shall be drawn without taking into account the contribution of the collateral
sound transmission paths, as follows:
- a horizontal line segment (B-C) with the y-coordinate RB = RC shall be plotted in
the congruence area;
- a descending line segment with a slope of 6 dB/octave shall be plotted from
frequency “fB” towards the start point of the axes, until the 100 Hz frequency is
reached; the point of intersection with the y-coordinate shall be marked with A;
- and ascending line segment with a slope of 10 dB/octave shall be plotted from
frequency “fC” to frequency “2fC”, over a one-octave interval; segment C-D
shall be obtained;
- an ascending line segment with a slope of 6 dB/octave shall be plotted from
frequency “2fC” to the 3 150 Hz frequency; the segment obtained shall be
marked with D-E. The resulting curve “Ri(f)” is shown in Figure A.4.3.
The effect of the noise transmission via collateral paths shall be taken into consideration,
displacing the curve “Ri(f)” plotted in point 3 by the following value:
 Z

Ra  20 lg m  1 (dB)
 Z m,med 


97
(A.4.1)
Figure A.4.3 - Attenuation index curve “Ri(f)”
a - without taking into consideration the transmission via collateral paths
b - taking into consideration the effect of the transmissions via collateral
paths
where:
Zm
– mechanical impedance of the building element taken into consideration, in
daNs/m³;
Zm,med. – average mechanical impedance of the adjacent building elements which delimit
the sound receiving space of the element taken into consideration, in daNs/m³.
Zm
The ratio “ Z
” can be approximated with relationship:
m ,med .
Zm
Z m,med .

m P
 mi  li
(A.4.2)
where:
m
P
–
the mass per unit of surface area of the building element taken into
consideration, in kg/m²;
– perimeter of the building element, in metres;
mi – mass per unit of surface area of the adjacent building element “i”, in kg/m²;
li
– length of the contact surface between the adjacent building element “i” and
the element taken into consideration, in metres.
98
Calculation example
The attenuation index curve “Ri(f)” must be determined for the fired clay masonry wall
shown in Figure A.4.4.
Plan
Section 1-1
reinforced
reinforced
concrete
concrete
beam
pillar
fired clay partition wall
reinforced concrete
structural wall bulb
Figure A.4.4
1. Mass per unit of surface area of the partitioning element:
plaster made of lime
cement mortar
masonry made of fired
clay elements
m = 0.115  1800 + 2  0.015  1700 = 258 kg/m²
The frequency range for the congruence area porch and its related acoustic
attenuation index:
17000 17000

 66 Hz
m
258
77000 17000

fC =
= 298 Hz
m
258
RB = RC = 37 dB
Curve Ri(f), without taking into consideration the noise transmission via collateral
paths, is marked with “a” in Figure A.4.6.
fB =
Reduction of the acoustic attenuation index due to the influence of collateral paths:
99
 Zm

1
Ra = –20 lg 
 Z m ,med . 
Zm
Z m ,med .

(dB)
mP
4
 m  l
i 1
i
i
side in contact with the
reinforced concrete pillar
side in
contact with
the
reinforced
concrete
bulb
sides in contact with the
reinforced concrete beam
Figure A.4.5
Figure A.4.6 - Acoustic attenuation index curve Ri(f)
100
a – without taking into consideration the transmission via collateral paths
b – taking into consideration the effect of the transmissions via collateral
paths
c – curve of the reference values (reference curve)
l1= l2 = 2.15 m; m'1 = m'2 = 0.50  2 500 = 1 250 kg/m²
l3= l4 = 4.30 m;
m'3 = m'4 = 0.65  2 500 = 1 625 kg/m²
mP
258  22 ,15  4 ,30 

4
22 ,15  1250  4 ,30  1625  =0.172
 mi  li
i 1
Ra = –20 lg (0.172 + 1) = –1.38 dB
Curve Ri(f), for which the noise transmissions via collateral paths was taken into
consideration,is marked with “b” in Figure A.4.6. This curve shall help determine the
airborne sound insulation index “R'w” for the partitioning element by comparison with the
reference curve for the acoustic attenuation indices (“c”), in accordance with the
methodology stipulated in SR EN ISO 717-1, SR EN ISO 717-1/A1. The result is R'w =
48 dB.
II.
Determination of the curve “Ri(f)” for double-layered homogeneous elements
The simplified calculation method presented below shall apply to double-layered
homogeneous elements in which the distance between the two constituent layers does not
exceed 25 cm.
The acoustic attenuation index curve “Ri(f)” shall be determined as follows:
1. The attenuation index curves R1(f) and R2(f) for the two single-layered component
elements shall be determined in accordance with the methodology specified in point
I
2. Curve R(f) =R1(f) + R2(f) shall be plotted;
3. The final curve Ri(f) shall be determined with relationship:
Ri(f) = R(f) + Ra + Rb1(f) + Rb2(f) + Rc
where:
Ra

(dB) (A.4.3)
–
correction corresponding to the sound transmission via collateral
paths, in dB;
Rb1
–
correction corresponding to the acoustic absorption of the space
between the two single-layered component elements, in dB;
Rb2
–
correction corresponding to the stabilisation of stationary waves in the
space between the two single-layered component elements, in dB;
Rc
–
correction corresponding to the mechanical coupling of the two
single-layered component elements, in dB.
The correction “Ra” shall be determined with relationship:
 Z m1  Z m 2 
 1
Ra = –40 lg  Z
 m ,med

where:
Zm1,2
–
(dB)
(A.4.4)
mechanical impedances corresponding to each of the single-layered
101
component elements, in daNs/m³;
Zm,med
–
average mechanical impedance of the building elements adjacent to
the single-layered element taken into consideration, in daNs/m³.
Notes:
1. Relationship (A.4.4) shall apply when the adjacent building elements are
continuous for the entire thickness of the structure analysed;
2. The ratio
Z m1  Z m 2
Z m ,med can be approximated with relationship:
Z m1  Z m 2 P 1m1   2 m2 

4
Z m ,med
 mi  li
1, 3
(A.4.5)
i 1
where:
m1,2 – masses per unit of surface area for each of the two single-layered
component elements, in kg/m2;
m'i
– mass per unit of surface area of the adjacent element “i”, in kg/m²;
P
– perimeter of the building element analysed, in metres;
li
– length of the side “i” of the adjacent building element, in metres;
102
1,2 – coefficients which take into account the way in which the singlelayered component elements are fixed to the adjacent building
elements; ( = 1.0 for encasing; this is the case with monolithic
reinforced concrete elements where continuity in the joints is
reliable;  = 0.8 for the joint; this is the case with disconnected
retainers).

The correction “Rb1(f)” shall be determined with relationship:
Rb1(f) = –10 lg 
1
m
f 
(dB)
(A.4.6)
where:
m(f ) – average acoustic absorption coefficient for the inner surfaces of the
space between the two single-layered structural elements, at
frequency “f “.
Note:

For covering purposes, the favourable effect of any sound-absorbing
treatments applied along the retaining elements installed between the two
single-layered component elements can be overlooked.
The correction “Rb2(f)” shall be determined as follows:
the string of stabilisation frequencies “fn” shall be calculated with relationship:
fn =
17000 n
d
(Hz)
(A.4.7)
where:
Note:
d
– distance between the two single-layered component elements, in cm;
n
– string of natural numbers.
Each frequency in the string “fn”, calculated with relationship (A.4.7),
shall be marked near the centre frequency corresponding to the one-third
octave in which it is included.
the corrections “Rb2(f)” for the frequencies “fn” shall be adopted depending on the
value “m(f)”, in accordance with Table A.4.2.
Table A.4.2.
m(f)
 0.10
0.10 …  0.25
0.25 …  0.50
 0.50
Rb2(f), in dB
–6
–4
–2
0
The correction “Rb2” shall be applied to the “R(f)” curve as follows:
- for two consecutive frequencies “fn”, separated by a 2/3 octave interval , in
accordance with Figure A.4.7;
-
for two or more consecutive frequencies “fn” separated by a 1/3 octave interval, in
accordance with Figure A.4.8.
103
 2/3 octave
fn
fn+1
Figure A.4.7

1/3 octave
f n
fn+1
Figure A.4.8
The correction “Rc” shall modify the curve “R(f ) + Ra +Rb1 +Rb2”, as follows:
the coupling frequency, “f0”, of the single-layered component elements shall be
calculated with relationship:
f0 
1
2
m1  m2 k1  k 2   m1  m2 2 k1  k 2 2  4m1m2 k 22  2k1k 2 
2m1m2
(Hz) (A.4.8)
where:
m1,2 – mass per unit of surface area for each of the two single-layered component
elements, in kg/m²;
k1
– stiffness of the coupling elements located between the two single-layered
component elements, in daN/m³;
k2
– stiffness with which the two single-layered component elements are fixed
to the adjacent structural elements, in daN/m³.
In the practical situation of double structural elements with a mass m = m1 + m2  250
kg/m², the coupling frequency can be approximated with relationship:
f0 
 1
1
1 

k1  
2
 m1 m2 
(Hz)
(A.4.9)
where the notations have the same meanings as in relationship (A.4.8).
104
Note:
If the bending stiffness of the single-layered component elements is reduced to
no more than a third of the stiffness of the reinforcement elements by means of
structural measures, the stiffness “k1” shall predominantly depend on the
stiffness of the product inserted in the gap between the two single-layered
component elements. Under these conditions, the stiffness “k1” can be
determined with relationship:
  p 1,2 4
k1 

10
(daN/m3)
(A.4.10)
d
d
where:

–
ratio between the specific heat capacity of air at constant pressure and
at constant volume;
p
–
constant pressure inside the gap between the two component elements
(usually atmospheric pressure), in daN/m2;
d
–
distance between the two single-layered component elements, in
metres.
- from frequency “f0” towards the start point of the axes, the highest of the
R1(f) and R2(f) curves, corresponding to the two single-layered component
elements, shall be adopted as the final curve;
- the highest of the R1(f) and R2(f) curves shall also be adopted from
frequency “f0” to the high frequencies, up to frequency “f1 + f “. “f ” shall be
determined as a function of the “df/d” ratio, using Table A.4.3; “df” is the
thickness of the sound-absorbing treatment and “d” is the distance between the
two single-layered component elements.
df /d
f
(in 1/3 octave)
0
0,25
0,35
0,50
6
4
3
2
Table A.4.3
0,70
0,85
1
0
- a straight line with a 12 dB/octave slope shall be plotted from frequency
“f1” to the high frequencies, up until the intersection with the curve “R(f) + Ra
+ Rb1 + Rb2”; the frequency at the point of intersection shall have the notation
“f2”;
- from frequency “f2” to the 3 150 Hz frequency, curve “R(f) + Ra +Rb1
+ Rb2” shall be adopted.
Calculation example
The attenuation index curve “Ri(f)” must be determined for the double homogeneous wall
shown in Figure A.5.9.
105
Plan
Section 1-1
reinforced
concrete
pillar
reinforced
concrete
beam
plaster made of lime
cement mortar
ACC strips
mineral wool with a density of 140 kg/m3
masonry made of fired clay elements
air layer
Figure A.4.9
1. m1, m2 shall be measured, and the characteristics of the porch in the congruence
area shall be determined using the relationships given in Table A.4.1. Curves
R1(f) and R2(f) shall be plotted using the methodology presented in A.4.I.
Single-layered component element 1
m1 = 0.075650 + 0.0151 700 = 74.25 kg/m²
RB = RC = 29 dB
6700
fB = 74,25  90 Hz
43000
fC = 74,25  579 Hz
Single-layered component element 2
m2 = 0.0631 800 + 0.0151 700 = 160.5 kg/m²
RB = RC = 37 dB
17000
fB = 160,5  106 Hz
77000
fC = 160,5  480 Hz
Correction Ra shall be determined
 Z m1  Z m 2

 1
Ra = –40 lg  Z
m , med


Z m1  Z m 2 P  1m1   2 m2 

4
Z m ,med
 mi  li
(dB)
1, 3
1

1 = 2 = 0.8
m'1 = m'2 = 0.502 500 = 1 250 kg/m²
m'3 = m'4 = 0.602 500 = 1 500 kg/m²
106
P  1m1   2 m2 
1, 3
4
 m  l
i
22,20  4,30 0,8  74,25  0,8  160,5
21250  2,20  1500  4,30 
1, 3


13  187,81,3

18400
i
1
11742
 0,638
18400

Ra = –40 lg (0.638 + 1) = –40  0.214  –8.5 dB

Correction Rb1 shall be calculated
1
Rb1 = –10lg  m
The values are calculated in Table A.4.4, taking into consideration (f ) for the two
products bordering the air layer, namely non-plastered ACC and high density mineral wool
(140 kg/m3);
Table A.4.4
Frequency
R1(f)
R2(f)
R=R1+R2
Ra
R+Ra
ACC
v.m.
m
Rb1
R+Ra+Rb1
50
63
80
100 125 160
24 26 28 29 29
30.7 32.7 34.7 36.7 37
54.7 58.7 62.7 65.7 66
29
37
66
200
250 315 400 500 630 800 1000 1250 1600 2000 2500 3150
29
37
66
29
37
66
29 29 29 30.4 33.8 37 39.8 41.8 43.8 45.8 47.8
37 37 37.5 41 44 47.3 49.3 51.3 53.3 55.3 57.3
66 66 66.5 71.4 77.8 84.3 89.1 93.1 97.1 101 105
–8,5
46.2 50.2 54.2 57.2 57.5 57.5 57.5 57.5 57.5 57.5 58 62.9 69.3 75.8 80.6 84.6 88.6 92.6 96.6
0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.05 0.05
0.08 0.08 0.12 0.16
0.2 0.35 0.4 0.65 0.7 0.82 0.94 0.96 0.98
1
0.96 0.98
0.05 0.05 0.07 0.09 0.11 0.19 0.21 0.34 0.37 0.43 0.49 0.5 0.52 0.52 0.52 0.52
-13
-13
-12 -10.5 -9.6 -7.2 -6.8 -4.7 -4.3 -3.7 -3.1
44.2 44.5 46
47
-3
-2.8 -2.8 -2.8 -2.8
47.9 50.3 50.7 53.3 58.6 65.6 72.7 77.6 81.8 85.8 89.8 93.8
Correction Rb2 shall be calculated
17000 n
d
d = 10 cm
17000 1
f1 =
= 1 700 Hz (the correction shall be made near the 1600 Hz
10
frequency)
17000  2
f2 =
= 3 400 Hz
 outside of the usable frequency range.
10
Because, at f = 1 600 Hz, m > 0.50 (Table A.4.3), this results in Rb2 = 0, in
accordance with the values given in Table A.4.2.
fn =
Correction Rc shall be calculated
m1 + m2 = 74.25 +160.5 = 235 kg/m² < 250 kg/m²
1,2
1,2
4
4
 k1 = d 10  0,1 10 daN/m³
f0 =
 1
1
1 
1,2
1 
 1
  0,5
k1  
104 

 = 24.34  25 Hz
2
0,1
 74,25 160,5 
 m1 m2 
107
df
4
 0.4  f = 2.5  (1/3 octave)
d 10
f1 = 25 + 2.5  1/3 octave
2.5 x 1/3 octave = 0.833 octave  1 octave

25 315 40 50
f0 1 octave f1
Diagram Ri(f) determined this way and plotted in Figure A.4.10 can be used to
obtain the airborne sound insulation index “Rw” by comparison with the reference curve, in
accordance with the methodology stipulated in SR EN ISO 717-1, SR EN ISO 717-1/A1.
For the double wall analysed above, the result shall be Rw = 60 dB.
Figure A.4.10
108
ANNEX 5
VALUES OF THE AIRBORNE SOUND INSULATION INDEX RW FOR
VARIOUS STRUCTURES OF PARTITION ELEMENTS
Ite
m
No
Total
mass
(kg/m2)
Structure
0
Value of the
airborne sound
insulation index
RW (dB)
3
1
2
A. SINGLE-LAYERED PARTITION ELEMENTS
A.I.1. Non-plastered reinforced concrete walls and slabs (ρ reinforced concrete =
2 500 kg/m3)
1 10 cm panels
250
49
2 11 cm panels
275
50
3 12.5 cm panels
312.5
51
4 14 cm panels
350
52
5 16 cm panels
400
53
6 18 cm panels
450
54
7 20.5 cm panels
512.3
55
8 23 cm panels
575
56
9 26 cm panels
650
57
A.I.2. Special reinforced concrete slabs
22 cm strips with openings and a 1 cm thick
10
400
74
layer of plaster
A.I.3. Reinforced concrete walls plastered on both sides with a 1 cm thick layer of
plaster (ρ plaster = 1900 kg/m3)
Walls with a reinforced concrete thickness of 11
11
313
51
cm (1 cm + 11 cm + 1 cm)
Walls with a reinforced concrete thickness of
12
400.5
53
14.5 cm (1 cm + 14.5 cm + 1 cm)
Walls with a reinforced concrete thickness of 19
13
513
55
cm (1 cm + 19 cm + 1 cm)
Walls with a reinforced concrete thickness of
14
650
57
24.5 cm (1 cm + 24.5 cm + 1 cm)
A.II. Fired clay masonry walls plastered on both sides with a 2 cm thick layer of
plaster (ρ plaster = 1700 kg/m3)
Solid masonry made of fired clay elements (ρ =
15 1 800 kg/m3) with a thickness of 1/2 fired clay
275
49
element (2 cm + 11.5 cm + 2 cm)
Solid masonry made of fired clay elements (ρ =
16 1 800 kg/m3) with a thickness of 1 fired clay
500
54
element (2 cm + 24 cm + 2 cm)
Solid masonry made of fired clay elements (ρ =
17 1 800 kg/m3) with a thickness of 1 and 1/2 fired
725
57
clay element (2 cm + 36.5 cm + 2 cm)
Split block masonry made of fired clay elements
18 (ρ = 1 600 kg/m3) with a thickness of 1 fired clay
532
54
element (2 cm + 29 cm + 2 cm)
Ceramic blocks with horizontal gaps (ρ =
19
406
52
1 200 kg/m3) with a thickness of 1 block (2 cm +
109
29 cm + 2 cm)
A.III. Autoclaved cellular concrete (ACC) walls
20 7.5 cm strips
49.5
32
21 10 cm strips
66
34
22 12.5 cm strips
82.5
35
3
Blocks with ρ = approximately 650 kg/m
23 plastered on both sides with a 2 cm layer of
198
46
plaster; ρ = 1 700 kg/m3 (2 cm + 20 cm + 2 cm)
Blocks with ρ = approximately 630 kg/m3
24 plastered on both sides with a 2 cm layer of
224
47
plaster; ρ = 1 700 kg/m3 (2 cm + 24 cm + 2 cm)
A.IV. Non-plastered granulite reinforced concrete walls (ρ reinforced concrete = 2500
kg/m3)
Granulite reinforced concrete walls, ρ =
25
360
53
1 800 kg/m3 (20 cm)
Granulite reinforced concrete walls, ρ =
26
270
50
1 800 kg/m3 (15 cm)
A.V. Walls made of wooden products
Walls made of 7 cm thick sandwich panels with
the following structure:
27 - Hardwood fibreboard, 0.5 cm;
32
34
- Porous wood fibre board, 6 cm;
- Hardwood fibreboard, 0.5 cm;
Walls made of 9 cm thick sandwich panels with
the following structure:
- Hardwood fibreboard, 0.5 cm;
- Porous wood fibre board, 2 cm;
28
27
42
- air, 1 cm;
- porous boards, 3 cm;
- Porous wood fibre board, 2cm;
- Hardwood fibreboard, 0.5 cm;
B. MULTI-LAYER PARTITION ELEMENTS
29
30
31
32
Structure:
- ACC strip, 7.5 cm;
- porous boards, 7 cm;
- air, 6 cm;
- ACC strip, 7.5 cm
Structure:
- ACC strip, 12.5 cm;
- air, 10 cm;
- ACC strip, 12.5 cm
Structure:
- ACC strip, 10 cm;
- porous boards, 4 cm;
- air, 1 cm;
- ACC strip, 10 cm
Structure:
- ACC strip, 12.5 cm;
- porous boards, 4 cm;
- air, 1 cm;
110
104
51
164
51
135
52
135
52
33
34
35
36
37
38
39
40
41
42
43
- ACC strip, 7.5 cm
Structure:
- ACC strip, 12.5 cm;
- porous boards, 4 cm;
- air, 6 cm;
- ACC strip, 7.5 cm
Structure:
- masonry consisting of 1/2 fired clay element
with exterior plaster, 2 cm;
- porous boards, 7 cm;
- air, 6 cm;
- ACC strip, 7.5 cm
Structure:
- non-plastered reinforced concrete, 5 cm;
- air, 10 cm;
- non-plastered reinforced concrete, 5 cm
Structure:
- non-plastered reinforced concrete, 14 cm;
- air, 6 cm;
- masonry consisting of 1/4 fired clay element
with 2 cm thick exterior plaster
Structure:
- non-plastered reinforced concrete, 14 cm;
- air, 6 cm;
- porous boards, 4 cm;
- masonry consisting of 1/4 fired clay element
with 2 cm thick exterior plaster
Structure:
- non-plastered reinforced concrete, 5 cm;
- air, 6 cm;
- non-plastered reinforced concrete, 5 cm
Structure:
- non-plastered reinforced concrete, 7 cm;
- air, 6 cm;
- non-plastered reinforced concrete, 7 cm
Structure:
- granulite concrete, 8 cm;
- air, 6 cm;
- granulite concrete, 8 cm
Structure:
- granulite concrete, 8 cm;
- air, 10 cm;
- granulite concrete, 8 cm
Structure:
- gypsum strip with gaps filled with cellular
cardboard, 7 cm;
- porous boards, 3 cm;
- air, 5 cm;
- gypsum strip with gaps filled with cellular
cardboard, 4 cm
Structure:
111
135
53
408
53
250
53
486
55
489
57
250
52
350
55
288
53
288
54
80
51
66
52
- sandwich panels, 7 cm;
- porous boards, 2 cm;
- air, 4 cm;
- sandwich panels, 7 cm
112
ANNEX 6
GUIDE METHOD FOR CALCULATING THE AIRBORNE SOUND
INSULATION INDEX “Rw” FOR SINGLE AND DOUBLELAYERED HOMOGENEOUS CLOSING ELEMENTS
I.
Single-layered elements
The airborne sound insulation index “Rw” can be determined, for guidance, with
relationship:
Rw = Rw – c
(dB)
(A.6.1.)
where:
Rw – airborne sound insulation index of the closing element, without the
contribution of the sound transmission via collateral paths, in dB;
c
– correction which estimates the reduction in the airborne sound insulation
capacity due to the transmission of noise via collateral paths;
Index “Rw” shall be determined as a function of the mass per unit of surface area of the
structural element, using the diagram shown in Figure A.6.1.
Correction “c” shall be determined with relationship:
 Zm

1
c = 10lg 
(dB) (A.6.2)
 Z m ,med

where:
Zm – mechanical impedance of the coupling element taken into consideration, in
daNs/m³;
Zm,med – average mechanical impedance of the building elements adjacent to the
closing element taken into consideration, in daNs/m³.
The “Zm/Zm,med” ratio can be approximated with relationship:
Zm
Z m ,med

mP
4
 m  l
i 1
i
(A.6.3)
i
where:
m
– the mass per unit of surface area of the closing element taken into
consideration, in kg/m2;
mi – the mass per unit of surface area of the closing element taken into
consideration, in kg/m²;
P
– perimeter of the closing element taken into consideration, in metres;
li
– length of the contact surface between the adjacent structural element “i”
and the closing element taken into consideration, in metres.
If the structural element “i” adjacent to the closing element taken into consideration has
different structures (“mie” in the sound emitting room and “mir” in the sound receiving
room), the value “mi” shall be determined with relationship:
mie  mir
mi =
(kg/m²) (A.6.4)
2
113
1) The mass tolerances compared with the diagram, for homogeneous and airtight elements are
+ 4 %;
2) Elements with a mass between 10 - 40 kg/m2 may display deviations larger than 4 % (absolute
value) from the diagram.
Figure A.6.1. Law of mass
114
II.
Double elements
The airborne sound insulation index “Rw” for double elements can also be determined, for
guidance, with relationship (A.6.1).
Index “Rw” shall be determined using the diagram shown in Figure A.6.1, as a function of the total
mass per unit of surface area of the two single-layered components.
if the following requirement is complied with,
mmin  d  100
(kg  cm/m²) (A.6.4)
the value of the index “Rw”, determined as specified above, shall be increased by 4–6 dB. If, in
this situation, a continuous layer of sound-absorbing material with a thickness of at least 3 cm is
inserted in the gap between the two single-layered components making sure that the gap is not
completely obstructed, an additional value Rw shall be added to the index “Rw”, in accordance
with Table A.6.1.
Table A.6.1.
Thickness of the sound-absorbing Rw (dB)
layer (cm)
3
4
5
5
8
6
Correction “c” shall be determined with relationship A.6.2 for each of the two single-layered
components of the double element. The largest value of correction “c” shall be used to calculate
the airborne sound insulation index “Rw”.
Calculation example
1. The airborne sound insulation index “Rw” must be determined, using the guide method, for
the fired clay masonry wall analysed in the calculation example given in Annex A.4.I.
m=
250 kg/m²
According to the diagram shown in Figure A.6.1, Rw = 49 dB.
Zm
m P
 4
 0,172
Z m,med
 mi  li
i 1
c=
Rw =
10lg (0.172 + 1) = 10  0.069 = 0.69 dB
Rw – c = 49 – 0.69 = 48.31 dB  48 dB
2. The airborne sound insulation index “Rw” must be determined, using the guide method, for
the double homogeneous wall analysed in the calculation example given in Annex A.4.II.
m = m1 + m2 = 74.25 + 160.5 = 234.75 kg/m²
According to the diagram shown in Figure A.6.1, Rw = 48 dB
For the  component of the wall:
Zm
Z m,med

m P
4
 m  l
i 1
i

74,25  22,20  4,30 965,25

 0,052
18400
18400
i
For the  component of the wall:
115
Zm
Z m,med

m P
4
 m  l
i 1
i

160,5  22,20  4,30 2086,5

 0,113
18400
18400
i
Correction “c” shall be determined with relationship (A.6.2) for the highest Zm/Zm,med ratio.
 Zm

1 = 10lg (0.113 + 1) = 10  0.046 = 0.46  0.5 dB
c = 10lg  Z
 m ,med

The “Rw” index shall be determined with relationship (A.6.1)
Rw = 48 – 0.5 = 47.5 dB
The product is mmin  d = 74.25  10 = 742.5 kgcm/m² > 100 kgcm/m², therefore an
additional value Rw,1 = 4–6 dB shall be applied to the R´w value calculated previously.
A 4 cm layer of sound-absorbing material is inserted in the air gap between the two singlelayered components. Therefore, an additional value Rw,2 = 4.5 dB shall be applied, in
accordance with Table A.6.1.
Rw = 47.5 + Rw,1 + Rw,2 = 47.5 + (4 - 6) + 4.5 = 56 - 58 dB.
116
ANNEX 7
ACOUSTIC ABSORPTION COEFFICIENTS (f) FOR CERTAIN
FINISHINGS AND OBJECTS THAT ARE FREQUENTLY USED
IN STRUCTURES (DETERMINED USING THE
REVERBERATION CHAMBER METHOD – SR EN ISO 354)
Ite
Name of material
Absorption coefficients “i(f)” for frequencies (Hz)
m
125
250
500
1 000 2 000 4 000
No
1
Plaster with a thickness of at least 20
mm, applied in two layers (primer +
0.02
0.02
0.03
0.04
0.05
0.05
mortar) on any supporting surface,
painted with water-based paint
2
Primed plaster, painted with water-based
0.02
0.02
0.03
0.03
0.04
0.05
paint
3
Primed plaster, painted in oil
0.01
0.01
0.02
0.02
0.03
0.03
4
Mortar applied to the concrete
prefabricated elements, painted with 0.02
0.02
0.02
0.03
0.04
0.04
water-based paint
5
Plasterboard panels
0.02
0.02
0.03
0.03
0.04
0.05
6
Parquet flooring
0.04
0.04
0.06
0.08
0.08
0.1
7
PVC flooring
0.02
0.02
0.03
0.04
0.04
0.05
8
Mosaic flooring
0.01
0.01
0.02
0.02
0.03
0.03
9
Marble
0.01
0.01
0.02
0.02
0.03
0.03
10 Glass applied rigidly on a supporting
0.03
0.03
0.03
0.03
0.02
0.02
surface
11 Open window
1.0
1.0
1.0
1.0
1.0
1.0
12 Single glazed window
“(f)” shall be added to the values given at position
10 (in accordance with point 2.56)
13 Double window
It shall be dimensioned similar to a vibrating
membrane, with the second row of windows being
regarded as rigid support
14 Person inside the room, isolated (total 0.35
0.41
0.42
0.46
0.49
0.5
absorption)
15 Human gatherings
0.72
0.89
0.95
0.99
1.0
1.0
16 Polished pine wood boards applied to a 0.02
0.02
0.03
0.04
0.04
0.05
supporting surface
17 Pine wood doors
“(f)” shall be added to the values given at position
16 (in accordance with point 2.56)
18 Absorption of a plywood chair
0.02
0.02
0.02
0.04
0.04
0.03
19 Absorption of an upholstered armchair 0.10
0.23
0.23
0.22
0.19
0.18
covered with fabric (minimum values)
20 Electrostatically-laid carpet
0.08
0.11
0.12
0.25
0.37
0.46
21 Absorption of an upholstered armchair
0.4
0.7
0.9
0.9
1
1
covered with plush fabric
22 Wooden furniture
0.02
0.02
0.03
0.04
0.04
0.05
23 Woven carpet
0.14
0.16
0.18
0.33
0.5
0.7
117
118
ANNEX 8
METHOD FOR DETERMINING THE CURVE OF THE SOUND
ABSORPTION COEFFICIENTS “αi(f)” FOR VARIOUS SOUNDABSORBING STRUCTURES
a) Porous boards installed away from the supporting layer
The maximum value of the sound absorption coefficient can be determined with the
following relationship:


 max  1  0.1
d 

h2 
f1
 0
f0
(A.8.1)
where:
h – thickness of the porous board (cm);
d – distance between the board and the supporting layer (cm);
f0 – frequency from which the sound absorption coefficients remain constant (at
the maximum value) until the end of the range, if the porous boards are installed directly on
the supporting layer (Hz);
f1 – frequency from which the sound absorption coefficients remain constant (at
the maximum value) until the end of the range, if the porous boards are installed at a distance
“d” from the porous layer (Hz);
α0 – the constant maximum value of the sound absorption coefficient in the
frequency sub-range “f0 ….4 000” (when the boards are installed directly on the supporting
layer).
The frequency “f1” can be determined with relationship:
f1 
c
(Hz)
4d  2.5h 
(A.8.2)
where:
c – speed of sound propagation through air (340 m/s);
d, h – have the same meanings as in relationship A.8.1.
For guidance, the curve of coefficients “  i ( f ) ” for porous boards installed away from
the supporting layer shall be plotted as follows:
a horizontal porch with a value  max shall be plotted from frequency “f1” to the
end of the frequency range;
- a straight line shall be drawn from frequency “f1” to the start of the frequency
range, whose descending slope ensures that the “  ” values decrease by 50 %
for each octave.
b) Porous boards installed directly on or away from the supporting layer, protected by
perforated plates.
The final values of the absorption coefficients “final” shall be determined, as a function of
the degree of perforation and thickness of the plate, with the following relationship:
-
αfinal = αporous material ∙ τperforated plate
(A.8.3)
where τ is the transmission index of the perforated plate, determined using the diagrams
shown in Figure A.8.1.
119
transmission index τ
degree of perforation “ε” %
plate thickness (mm)
transmission index  of the perforated
plates as a function of the frequency
f0,5 for perforated plates as a
function of the degree of
perforation “” and the thickness of
the screen
Note: f0,5 is the frequency for which the absorption coefficient of the structure is
equal to 5 % of the absorption coefficient of the porous material
Figure A.8.1 – Diagram for deducting the transmission index 
c) Vibrating membranes
The curve of coefficients “  i ( f ) ” shall be determined as follows:
- the resonant frequency shall be determined with relationship:
f0 
850
(Hz) (A.8.4)
md
where:
m – mass per unit of surface area of the membrane, in kg/m2 ;
d – distance between the membrane and the supporting surface, in cm.
- the value “  max ” shall be chosen for the membrane, which corresponds to the
resonant frequency depending on the material from which it is made, given in Table
A.8.1.
Table A.8.1.
Item
No
Material of the membrane
αmax
1
Pine plywood
0.50
2
Chipboard
0.40
3
Window glass
0.30
4
Hard PVC
0.30
120
5
Steel sheet
0.08
- curve “  i ( f ) ” shall be plotted starting from value “  max ” near frequency f0, as
follows:
1) for membranes without sound-absorbing products inserted in the air gap:
- for each octave to the left and to the right of value f0, the sound absorption
coefficient “  max ” shall decrease by 50 % until it reaches the value of 0.05,
after which it shall remain constant (see Figure A.8.2);
vibrating
membrane
wall
Figure A.8.2 – Determination of the curve of coefficients “ ““” for a vibrating membrane
without a sound-absorbing substrate
2) for membranes with sound-absorbing products inserted in the air gap, with a
thickness of 0.3 - 0.8d:
- for each two octaves, to the left and to the right of value f0, the sound absorption
coefficient “  max ” shall decrease by 50 % until it reaches the value of 0.05,
after which it shall remain constant (see Figure A.8.3);
vibrating
membrane
wall
Figure A.8.3 – Determination of the curve of coefficients “” for a vibrating membrane with a
sound-absorbing substrate
121
Examples of calculations for determining the curve of the absorption coefficients “
 i ( f ) ” for various sound-absorbing structures.
a) 3 cm thick mineral wool boards, installed 4 m away from a rigid support.
The maximum value of the sound absorption coefficient for this structure shall be
calculated with relationships A.8.1 and A.8.2.
c
3400
3400
f1 


 739 Hz
4d  2.5h  44  2.5  3
46


 max  1  0.1
d  f1
4  739

  0  1  0.1 2 
 0.898  0.90
2 
h  f0
3  1000

 max  0.90
The curve of the sound absorption coefficients “  i  f  ” shall be plotted in
accordance with point a of Annex 8 (see Figure A.8.3).
b) Beech plywood membrane with a thickness of 5 mm, located 15 cm away from
a wall, without a sound-absorbing substrate.
experimental
calculation
Figure A.8.4
The resonant frequency shall be calculated with relationship A.8.4.
f0 
850
850

 110 Hz
md
4 15
The curve of the sound absorption coefficients “  i  f  ” shall be plotted in accordance
with point c.1. of Annex 8 (see Figure A.8.5).
122
experimental
calculation
Figure A.8.5
c) Beech plywood membrane with a thickness of 5 mm, located 15 cm away from a wall, with a
substrate made of mineral wool with a density of 90 kg/m3 and a thickness of 5 cm.
The resonant frequency shall be identical to the one specified in example “b”, namely
110 Hz.
The curve of the sound absorption coefficients “  i  f  ” shall be plotted in accordance with point
c.2. of Annex 8 (see Figure A.8.6).
123
experimental
calculation
Figure A.8.6
124
ANNEX 9
VALUES OF THE INSULATION INDEX Ln,eq,o,w FOR REINFORCED
CONCRETE SLABS
Item
No
Slab structure
Ln,eq,o,w
(dB)
1
Slab - 10 cm thick
80
2
Slab - 11 cm thick
79
3
Slab – 12 cm thick
78
4
Slab - 14 cm thick
77
5
Slab - 16 cm thick
76
6
Strips with gaps (22 cm thick) with plaster (1
cm thick) + levelling screed (3 cm thick)
77
7
Structure:
reinforced concrete slab, non-plastered
(10 cm thick);
air (8 cm thick);
porous boards (2 cm thick);
- plasterboard (1.25 cm thick);
125
70
ANNEX 10
IMPROVEMENT OF THE IMPACT SOUND INSULATION LW
FOR VARIOUS TYPES OF FLOORING
Improvement
Ite
m
No
Type of flooring
of the impact
sound
insulation
LW
(dB)
Parquet
1
2
Traditional parquet installed on wooden beams glued onto the concrete slab
Parquet installed on wooden beams and an elastic layer with a thickness of
2.5 cm
11
21
Carpets, rugs
3
4
5
6
7
8
9
Rubber flooring with a thickness of 3–4 mm
PVC flooring without a textile lining, with a thickness of 1.5–2 mm
PVC flooring with a textile lining, with a thickness of 2–5 mm
PVC flooring with a textile lining, with a thickness of 2.5–5 mm
PVC flooring with a sound-insulating support, with a minimum thickness of
2.5mm
Carpet made of electrostatically-applied polyamide fibres, with a soundinsulating support made of expanded PVC
Unwoven carpet
5
7
9
11
16
18
20
Floating slabs
10
11
12
13
Parquet or PVC flooring without a textile support, glued to the floating concrete
slab over an elastic layer or mineral wool with a minimum thickness of 10 mm
Idem, over an elastic layer with a minimum thickness of 30 mm
Idem, over an elastic layer of cold-hardened polystyrene
Idem, over the impact sound insulating membrane
126
23
28
22
20...27
ANNEX 11
CALCULATION OF THE IMPACT SOUND INSULATION
IMPROVEMENT INDEX, „Lw”, FOR A FLOATING SLAB FLOOR
The impact sound insulation improvement index, “Lw”, for a floating slab floor shall be
calculated as follows:
1.
A reference floor slab (reinforced concrete slab with a thickness
of 12 cm) shall be adopted, with known values for the normalised noise level “Ln,r,o” (Table A.11.1
and Figure A.11.1) and the impact sound insulation index Ln,r,o,w = 78 dB.
Table A.11.1
Frequency
100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150
(Hz)
Ln,r,o (dB) 67 67.5 68 68.5 69 69.5 70 70.5 71 71.5 72
72
72
72
72
72
Figure A.11.1
a – curve Ln,r,o of the reference floor slab
b – reference curve of the normalised impact noise levels
127
2. A certain elastic layer shall be chosen, which shall have a
thickness “h” and the specific dynamic stiffness “k”, in MN/m³, in
accordance with Table A.11.2.
Ite
m
Name of the product
No
1 Boards made of cold-hardened
cellular polystyrene
2 Porous mineral wool boards
(  100 kg/m³)
3 Synthetic rubber membranes glued
with polyurethane resin
 =720 kg/m³
 =800 kg/m³
Layer thickness
(mm)
Table A.11.2
Specific dynamic
stiffness “k” (MN/m³)
10
15
20
20
8 . . . 10
54
58
Notes:
For other thicknesses of the elastic products (up to 50 mm), the specific dynamic stiffness
shall be determined by measurements in accordance with STAS 8048/1, if not specified in the
technical agreements concluded for the respective products.
For guide calculation, it shall be considered that the specific dynamic stiffness of the product
is inversely proportional to the variation of the layer thickness.
3. The natural frequency of the dynamic system consisting of a slab applied over an elastic layer
shall be determined with relationship:
f 0  160
where:
k
m
–
k
m
(Hz)
(A.11.1)
specific dynamic stiffness of the elastic layer, in MN/m³;
–
mass per unit of surface area corresponding to the slab and the floor wear
layer, in kg/m2.
4. The curve for the normalised levels “Ln(f )”, corresponding to the structural assembly
comprising of the reference floor slab + the floating slab floor, shall be plotted as
follows:
-
for frequencies lower than frequency “f0”, curve “Ln(f )” shall be identical to curve “Ln,r,o”,
corresponding to the reference floor slab;
-
for frequencies higher than frequency “f0”, curve “Ln(f )” shall comprise of two line segments,
as follows:

the first segment, descending with a slope of 10 dB/octave until near frequency 4f0;
128

the second segment, descending with a slope of 8 dB/octave until near the frequency is
equal to 3 150 Hz.
Figure A.11.2 – Construction of curve Ln(f) corresponding to the structural assembly made up of
the “reference floor slab + floating slab floor”
5. The impact sound insulation index, “Ln,r,w”, corresponding to the structural assembly
comprising of the reference floor slab + floating slab floor shall be determined. The
methodology for such determination is stipulated in SR EN ISO 717-2,SR EN ISO 7172/A1,SR EN ISO 717-2/C91 and consists of comparing curve “Ln(f )”, plotted in
accordance with points 14, to the reference curve for the normalised impact noise
levels.
6. The impact sound insulation improvement index, “Lw”, for a floating slab floor shall
be calculated with relationship:
Lw = Ln,r,o,w – Ln,r,w = 78 dB – Ln,r,w
(dB)
(A.11.2)
Note: This annex makes use of the notations given in SR EN ISO 717-2,SR EN ISO 717-2/A1, SR
EN ISO 717-2/C91.
Calculation example
129
20
40
The impact sound insulation improvement index, “Lw”, for a floating slab floor shown in Figure
A.11.3 must be calculated.
PVC flooring without an elastic substrate (2.5 kg/m2)
cement mortar slab, h = 4 cm
Figure A.11.3
separating layer - polyethylene sheet
mineral wool plates, h = 2 cm
a) The specific dynamic stiffness of the elastic layer, in accordance with Table A.11.2, shall be
k = 20 MN/m³;
b) The mass per unit of surface area corresponding to the slab and wear layer of the floor:
m = 0.04  2200 + 2.5 = 90.5 kg/m²;
c) The natural frequency of the system represented by the floating slab:
f 0  160
k
20
 160
 75 Hz
m
90,5
d) The curve “Ln(f )” for the structural assembly comprising of the reference floor slab and the
floating slab floor shall be plotted in accordance with point 4 of this annex. Curve “Ln(f )” is
shown in Figure A.11.4.
The methodology stipulated in SR EN ISO 717-2, SR EN ISO 717-2/A1 and SR EN ISO 7172/C91 shall be used to determine the impact sound insulation index “Ln,r,w” corresponding to the
structural assembly comprising of a reference floor slab and a floating slab floor, by comparing
curve “Ln(f )” to the reference curve of the normalised impact noise levels. The result is “Ln,r,w” =
47 dB (value of the y-coordinate for a frequency of 500 Hz, on the reference curve of the
normalised impact noise levels, in the displaced position obtained by overlapping the reference
floor slab+floating slab assembly with curve “Ln(f )”; by convention, the two curves shall overlap
when the sum of the negative deviations of the real curve compared to the reference curve is
 32 dB).
e) The impact sound insulation improvement index shall be obtained with relationship
(A.11.2), as follows:
Lw = Ln,r,o,w – Ln,r,w = 78 – 47 = 31 dB.
130
Figure A.11.4. Determination of index Ln,r,w
a - curve “Ln,r,0” of the reference floor slab;
b - curve “L n (f)” of the reference floor with a floating slab;
c - reference curve of the normalised impact noise levels, in the displaced
position obtained by overlapping with curve “L n (f)”.
131
ANNEX 12
ELEMENTS OF ACOUSTIC CALCULATION OF VAC SYSTEMS
A12.1 The level of airborne noise produced by equipment in VAC stations, with a volume
of less than 1000 m3 and without any sound-absorbing treatments, shall be calculated as follows:
a) Fans
The airborne noise level shall be calculated with relationship


Lav  10 lg Qp02  k , [dB(A)]
(A12.1)
where the following notations were used:
Q - fan capacity [m3/h];
p0 - static pressure [mm H2O column];
k - correction coefficient which takes into account the type of fan [dB(A)].
The correction coefficient k shall be adopted depending on the type of fan, as follows:
10 axial fans k  15 [dB(A)]
20 centrifugal fans
-with forward-leaning blades k  10 [dB(A)]
k  5 [dB(A)]
-with backward-leaning blades
b) Electric motors (with a power of less than 100 kW)
The airborne noise level shall be calculated with relationship
Lac  10 lg Pn 2   10 ,
[dB(A)]
(A12.2)
where the following notations were used:
P - rated power of the electromotor [kW];
n - electromotor speed [rotations/min.].
c) Piston compressors
The airborne noise level shall be calculated with relationship
Lac  6 lgPn   65 , [dB(A)]
(A12.3)
where the following notations were used:
P - rated power of the compressor [kW];
n - compressor speed [rotations/min.].
d) Electric pumps
The airborne noise level shall be calculated with relationship (A12.2), since, during
operation of the electric pumps, the electric drive motors produce dominant noises.
A12.2 The overall acoustic power level of the fans can be calculated using the diagrams
shown in Figures A12.1, A12.2 and A12.3. These diagrams were determined using the following
relationships
Lv , p  22  10 lg Q  20 lg p0
[dB] (A12.4)
Lv , p  75  10 lg P  10 lg p0 [dB]
Lv , p  28  20 lg P  10 lg Q ,
where the following notations were used:
Q - fan capacity [m3/h];
(A12.5)
[dB]
132
(A12.6)
p0 - static pressure [mm H O column];
2
P - electromotor power [kW].
L
Depending on the type of fan, the acoustic power level v, p shall be distributed into 1/1
octave frequency bands in the 63–4 000 Hz range using the diagram shown in Figure A12.4.
133
Figure A12.1 Variation of the overall acoustic power level
as a function of the capacity Q and the static pressure p0
500 mm H2O
134
100 kW
0.05 kW
0.1 kW
0.2 kW
0.5 kW
1 kW
5 kW
2 kW
10 kW
20 kW
50 kW
Static pressure p0 [mm H2O
column]
Figure A12.2 Variation of the overall acoustic power level
as a function of the power P and the static pressure p0
135
7 kW
10 kW
14 kW
20 kW
2 kW
2.8 kW
4 kW
5 kW
Capacity Q
[m3/h]
Figure A12.3 Variation of the overall acoustic power level
as a function of the power P and capacity Q
136
0.05 kW
0.07 kW
0.1 kW
0.14 kW
0.2 kW
0.28 kW
0.4 kW
0.5 kW
0.7 kW
1 kW
1.4 kW
dB values that must be deducted
from the overall power level
attenuation, in dB
Figure A12.4 Distribution of the acoustic power level
a - axial fans
b - centrifugal fans, forward-leaning blades
c - centrifugal fans, backward-leaning blades
tubing length (m)
Equivalent diameter (m)
Figure A12.5 Noise attenuation due to straight channel sections
S - area of the real section of the ventilation channel (m2)
4S
dech
- equivalent diameter

137
Attenuation L [dB]
attenuation, in dB
A12.3 The aerodynamic noise
level attenuation due to the air jet
propagation conditions along the
ventilation channels shall be calculated
as follows:
a) Calculation
of
natural
attenuation
10 For the straight sections of
metal sheet, concrete or fired clay
masonry channels, the attenuation shall
be determined using the diagram given
in Figure A12.5. The attenuation
values shall be valid in every 1/1
Figure A12.6 Noise attenuation due to elbows
octave frequency band within the 63–
4 000 Hz range.
20 For the right-angle elbows of metal sheet, concrete or fired clay masonry channels, the
attenuation shall be determined using the diagram given in Figure A12.6.
30 For the sudden section changes of metal sheet, concrete or fired clay masonry channels, the
Ratio of the areas of the channel sections m =
S1/S2
Figure A12.7 Noise attenuation due to
sudden section changes
attenuation shall be determined using the diagram given in Figure A12.7. The attenuation values
shall be valid in every 1/1 octave frequency band within the 63–4 000 Hz range. The curve shown
in Figure A12.7 was plotted using the following relationship
2

1  m
L  10 lg
4m
,
[dB]
where the following notations were used:
138
(A12.7)
S1
S2 ;
S1 , S 2 - areas of the channel sections before and after the section change (using the same
measurement unit).
m
Attenuation
L [dB]
Atenuare
L [dB]
10
9
8
7
6
5
4
3
2
1Ratio of the areas of the channel sections
ni=Si/S
0 Figure A12.8 Noise attenuation due to branching
0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9
1
Raportul ariilor sec\iunilor canalului ni=Si/S
Figure A12.8 Noise attenuation due to branching
40 For the branches of metal sheet, concrete or fired clay masonry channels, the
attenuation shall be determined using the diagram given in Figure A12.8. The attenuation values
shall be valid in every 1/1 octave frequency band within the 63–4 000 Hz range. The curve shown
in Figure A12.8 was plotted using the following relationship
L  10 lg
1
ni ,
[dB]
(A12.8)
where the following notations were used:
S
ni  i ;
S
S, Si - area of the channel section before the branch, and the area of the branch section “i”
(using the same measurement unit).
b) Calculation of the attenuation level using special methods
10 The attenuation obtained by lining a ventilation channel section with a soundabsorbing material shall be determined with the following relationship
L  1,05l
P 1, 4
 , [dB]
S
(A12.9)
where the following notations were used:
l - length of the lined area of the channel [m];
P - perimeter of the cross-section of the lined channel section [m];
S - cross-sectional area of the lined channel section [m2];
 1, 4 - coefficient determined as a function of the absorption coefficient  using the
139
diagram shown in Figure A12.9;
 - sound absorption coefficient corresponding to the sound-absorbing lining applied to the
channel section (at the frequencies for which the attenuation level is determined).
Relationship (A12.9) shall be valid for the frequency range in which the following requirement is
met
d
d ,
2
[m]
(A12.10)
where: d is the diameter or largest dimension of the cross-section of the channel [m];
 - wavelength [m] corresponding to the frequency for which the attenuation level is
being determined.
α1,
4
Absorption coefficient α
Figure A12.9 Variation curve for the term α1,4
20 The active attenuations obtained by installing expansion chambers shall be determined
with relationship
L  10 lg
A
S
 10 lg 2 , [dB]
S1
S1
(A12.11)
where the following notations were used:
A - equivalent sound absorption area corresponding to the inner surfaces of the
expansion chamber [m2 A.U.];
S1 - cross-sectional area of the ventilation channel [m2];
S 2 - cross-sectional area of the expansion chamber [m2];
Relationship (A12.11) shall be valid for the frequency range in which the condition (A12.10) is
met, where d is the largest dimension of the cross-section of the expansion chamber.
30 The reactive attenuations obtained by installing expansion chambers shall be
determined using the diagram shown in Figure A12.10. The curves in this diagram were plotted
using the following relationship
2
  m2 1
 
L  10 lg 1  
sin kl   , [dB]
  2m
 
140
(A12.12)
where the following notations were used:
S
m 1 ;
S2
2
k
;

S1 - cross-sectional area of the ventilation channel [m2];
S 2 - cross-sectional area of the expansion chamber [m2];
l - length of the expansion chamber [m];
 - wavelength [m] corresponding to the frequency for which the attenuation level is
being determined.
Relationship (A12.12) shall be valid for the frequency range in which the following requirement is
met
d ,
[m]
(A12.13)
where d is the diameter or largest dimension of the cross-section of the channel [m].
Attenuation ΔL [dB]
m = 100
m = 40
m = 25
m = 15
m=9
m=4
kl [rad]
Figure A12.10 Reactive noise attenuation due to expansion chambers
40 The attenuation obtained by installing basic circular active attenuators along the
ventilation channels shall be determined in accordance with the provisions stipulated in this
Annex, in Article A12.3b)10.
50 The attenuation obtained by installing circular active attenuators with a soundabsorbing bulb along the ventilation channels shall be determined by the manufacturer and
included in the technical specifications of these attenuators. Table A12.1 presents the main soundabsorbing characteristics of circular active attenuators with a sound-absorbing bulb.
Table A12.1
Values of the sound attenuation produced by circular attenuators with a soundabsorbing bulb, as a function of the frequency.
Frequency (Hz)
Ite
Attenuator diameter
m
63
125
250
500 1000 2000 4000 8000
(mm)
No
Attenuation (dB)
141
0
1
2
3
4
5
1
315
450
630
800
1000
2
3
4
5
6
7
8
9
1.5
1.5
10
24
30
30
17
11
60 The attenuation obtained by installing rectangular active attenuators with lamellae
along the ventilation channels shall be determined by the manufacturer and included in the
technical specifications of these attenuators. The diagrams shown in Figure A12.11 present the
main sound-absorbing characteristics of rectangular active attenuators with lamellae of types R1
and R2.
70 The attenuation obtained by installing rectangular active attenuators with baffles along
the ventilation channels shall be determined on the basis of the diagram shown in Figure A12.12,
whose curves were plotted using the following relationship
L  10 lg
4 N  1
,
1
[dB]
(A12.14)
where the following notations were used:
L
N ;
D
2ab
D
;
ab
a - width of the channel fitted with baffles [m];
b - width of the attenuator in a transverse direction [m];
L - length of the baffle path inside the attenuator [m];
 - sound absorption coefficient corresponding to the sound-absorbing treatment inside
the attenuator.
type
attenuation, in dB/m
type
Figure A12.11 Attenuation level achieved by lamellar rectangular attenuator
(type R1, R2 in accordance with Figure 4.1.17)
142
Attenuation ΔL [dB]
Figure A12.12 Noise attenuation ensured by rectangular active attenuators
with baffles (in accordance with Figure 4.1.8)
attenuation, in dB/m
A12.4 The level of attenuation during the intake or discharge of air into/from a room via a
ventilation hole, which is considered without a grate, shall be determined using the diagram shown
in Figure A12.13, as a function of the cross-sectional area of the air outlet, for 1/1 octave
frequency bands within the 63–2 000 Hz range.
A12.5 The noise level produced by an air jet passing through an air inlet or outlet hole fitted with
a grate shall be determined as follows:
octave band frequency
143
Figure A12.13 Noise attenuation at the exit from the ventilation channel via an outlet without a
grate
a) The overall noise level shall be determined with relationship
Lg  60 lg v  10 lg S  30 lg  ,
[dB]
(A12.15)
where the following notations were used:
v - speed of the air jet when passing through the grate [m/s];
S - area of the free section of the air inlet/outlet [m2];
 - aerodynamic resistance coefficient of the grate.
b) The overall noise level of the ceiling-mounted anemostats shall be determined with
relationship
Lga  60 lg v  13 lg S  33 , [dB]
(A12.16)
where the same notations were used as those in relationship (A12.15).
c) The noise level shall be distributed into frequency bands by correcting the overall acoustic
power level determined with relationship (A12.15) or relationship (A12.16), with the values given
in Table A12.2.
Table A12.2
Corrections of the overall acoustic power level for distributing the noise level into
frequency bands (with grates and anemostats)
Frequency (Hz)
63
125
250
500 1000 2000 4000 8000
Correction (dB)
-5
-6
-5
-6
-7
-10
-15
-20
possible positions
for the air inlets
d) If the noise level Lg is at least
10 dB lower than the aerodynamic
noise level produced during operation
aer
of the fan Lv , then it shall not be
taken into consideration when adding
up the noise power levels.
A12.6 The acoustic correction
of a room LA shall be determined
using the diagram shown in Figure
A12.16, depending on the following
characteristics of the room and VAC
system:
Figure A12.14 Determination of the geometric elements
a) the equivalent sound absorption
in order to obtain the directivity factor Q
area of the room A ;
b) the distance from the ventilation
channel entrance to the reference point d ;
(A, B, C, D), surface of the ventilation hole S and the angle  between the direction of the air
inlet and the normal line.
144
frequency ∙
suprafata
Figure A12.15 Determination of the directivity factor Q
145
Figure A12.16 Determination of the acoustic correction of the room
c) directivity factor Q . The directivity factor shall depend on the position of the ventilation hole
and the angle between the line perpendicular to the surface of the ventilation hole and the direction
towards the ventilation channel entrance, in accordance with Figure A12.14. The directivity factor
Q shall be determined for the 10–3 000 Hz frequency range using the diagram shown in Figure
A12.15, depending on the position of the ventilation holes.
A12.7 Procedure for determining the noise level transmitted within a room by a VAC
system - calculation example
branch pipe 2
introducing air into the hall
elbow: b = 1.00
m
branch: m = 0.5
elbow: b = 1.00
m
branch pipe 1
attenuator
section change: m =
0.3
acoustic correction, in dB
centrifugal fan
typ
e
Figure A12.17 Diagram of the VAC system
directivity factor Q
Problem:
The ventilated room is a club hall with a volume of 700 m3 (7Ý16,7Ý6 m) and an
equivalent sound absorption area of 100 m2 A.U., within the entire 63–8 000 Hz frequency band.
The VAC unit shall contain a centrifugal fan with backward-leaning blades, with the
following characteristics:
-rated capacity
Q=14 000 m3/h
-static pressure
p0=50 mm H2O column
-rated speed of the fan
nv=680 rotations/min.
-rated speed of the motor
nm=1 000 rotations/min.
The air shall be introduced into the hall using ceiling-mounted anemostats with the
following characteristics:
-surface area of the ventilation holes
S=0.15 m2
-air jet velocity
v=1.5 m/s
The diagram of the ventilation system is shown in Figure A12.17.
The requirement is to determine the dimensions of the attenuation systems of the
installation and check the ceiling-mounted anemostats so that the upper limit of the noise level
spectrum in the hall is represented by the noise curve CZ30.
Solution:
Calculation stages
a) Calculation of the overall acoustic power level of the fan and its distribution within 1/1 octave
DISTANCE TO THE
frequency bands:
RECEPTION POINT d(m)
0
1 Calculation of the overall acoustic power level of the fan with relationship (A12.4)
146
Lv , p  22  10 lg 14000  20 lg 50  97,4 [dB]
20 Distribution/correction of the level Lv, p within 1/1 octave frequency bands (using the
diagram shown in Figure A12.4, curve c - for a centrifugal fan with backward-leaning blades).
The corrections given in Table A12.3 were obtained.
Frequency (Hz)
Correction (dB)
63
-1
125
-6
250
-11
500
-16
1000
-21
2000
-26
Table A12.3
4000 8000
-31
-36
b) Calculation of the noise attenuation along the route of the installation:
10 The level of attenuation for the entire 63–8 000 Hz frequency range, due to sudden
section changes m  0,5 , was calculated with relationship (A12.7)
2

1  0,3
L  10 lg
4  0,3
 1,5
[dB]
20 The level of attenuation for frequencies within the 63–8 000 Hz range, due to a rightangle elbow b  1,00 m , was calculated in accordance with the diagram shown in Figure A12.6.
The results are presented in Table A12.4.
Table A12.4
Frequency (Hz)
63
125
250
500 1000 2000 4000 8000
L (dB)
0
-3.5
-6
-6
-7
-9.5
-11
-11
30 The level of attenuation for the entire 63–8 000 Hz frequency range, due to branching
ni  0,5 , was calculated with relationship (A12.8)
L  10 lg
1
 3
0,5
[dB]
40 The level of attenuation for the entire 63–8 000 Hz frequency range, due to the air
exiting the channel through branch pipe 1 (without anemostats), was calculated for the most
2
disadvantageous situation S i  0,30 m , in accordance with the diagram shown in Figure A12.13.
The results are presented in Table A12.5.
Table A12.5
Frequency (Hz)
63
125
250
500 1000 2000 4000 8000
L (dB)
-9
-5
-1
aer
c) The results of the calculation of the aerodynamic noise level Lv at the point where the air
exits the channel through branch pipe 1 (without grates or anemostats) are centralised in Table
A12.6.
Table A12.6
Calculation of the aerodynamic noise level at the channel exit (without grates or
aer
anemostats) Lv
Frequency (Hz)
Noise levels and their attenuation
(dB)
63
125
250
500 1000 2000 4000 8000
1
2
3
4
5
6
7
8
9
Noise level produced by the fan (dB)
147
Overall acoustic power level L p (dB)
Corrections for the distribution of the
level L p within frequency bands
(dB)
Noise level produced by the fan
during air discharge Lv, p (dB)
97,4
-1
-6
-11
-16
-21
-26
-31
-36
96.4
91.4
86.4
81.4
76.4
71.4
66.4
61.4
-1.5
-9.5
-3
0
-14
-1.5 -1.5
-11
-11
-3
-3
0
0
-15.5 -15.5
57.4
50.9
n
Natural attenuation of the noise level Lc throughout the installation (dB)
Sudden section change (dB)
-1.5 -1.5 -1.5 -1.5 -1.5
Right-angle elbow (dB)
0
-3.5
-6
-6
-7
Branch (dB)
-3
-3
-3
-3
-3
At the channel exit (dB)
-9
-5
-1
0
0
TOTAL natural attenuation (dB)
-13.5 -13 -11.5 -10.5 -11.5
Aerodynamic noise level at the
82.9 78.4 74.9 70.9 64.9
aer
n
channel exit Lv  Lv , p  Lc (dB)
45.9
d) Calculation of the noise level produced by air passing through anemostats Lga :
10 The overall noise level was calculated with relationship (A12.16)
Lga  60 lg 1,5  13 lg 0,15  33  32,9
[dB]
20 The distribution of the overall level within 1/1 octave frequency bands was corrected
in accordance with Table A12.2.
30 The results of the calculation Lga are presented, in a centralised way, in Table
A12.7.
Table A12.7
Calculation of the noise level produced by air passing through anemostats Lga
Noise levels and their corrections
(dB)
1
Overall noise level Lga (dB)
Correction (dB)
Noise level produced by air passing
through anemostats Lga (dB)
63
2
125
3
-5
-6
27.9
26.9
Frequency (Hz)
500 1000 2000
5
6
7
32.9
-5
-6
-7
-10
250
4
27.9
26.9
25.9
22.9
4000
8
8000
9
-15
-20
17.9
12.9
aer
Calculation of the aerodynamic noise level transmitted to the reception point Lv ,r :
10 Calculation of the acoustic correction due to the room LA - it was considered that
the most acoustically disadvantageous situation is present in the points located on the vertical axis
of the ventilation holes (at spectator level). The corrections for the 1/1 octave frequency bands
within the 63–8 000 Hz range were determined in accordance with the diagrams given in Figures
A12.14, A12.15 and A12.16.
The directivity factors Q corresponding to each frequency band were determined using
2
0
the diagram shown in Figure A12.15 (curve B) for   0 and S  0,15m .
The acoustic corrections were determined using the diagram shown in Figure A12.16 for
A  100 m 2U . A. and d  6  1,5  4,5m . The results are centralised in Table A12.8.
Table A12.8
Calculation of the acoustic correction due to the room LA
e)
148
1
Frequency f (Hz)
f S (Hzm)
Directivity factor Q
Acoustic correction LA (dB)
2
63
24.4
2.3
-14
3
125
48.4
2.9
-14
4
250
96.8
4
-13
5
6
7
8
9
500 1000 2000 4000 8000
193.6 387.3 774.6 1549.2 3098.4
5.6
6.8
7.3
7.4
7.2
-13
-12
-12
-12
-12
aer
20 The aerodynamic noise level transmitted to the reception point Lv ,r was calculated
aer
aer
with relationship Lv ,r  Lv  LA . The results for the 63–8 000 Hz frequency bands are
centralised in Table A12.9.
Table A12.9
aer
Calculation of the aerodynamic noise level transmitted to the reception point Lv ,r
1
Frequency f (Hz)
2
63
82.9
aer
Aerodynamic noise level Lv (dB)
-14
Acoustic correction LA (dB)
Aerodynamic noise level transmitted to
68.9
aer
the reception point Lv ,r (dB)
3
125
78.4
4
250
74.9
5
500
70.9
6
1000
64.9
7
2000
57.4
8
4000
50.9
9
8000
45.9
-14
-13
-13
-12
-12
-12
-12
64.4
61.9
57.9
52.9
45.4
38.9
33.9
f) Calculation of the noise level due to air passing through anemostats to the reception point
Lga,r and verification of the permissible noise level requirement for ensuring acoustic comfort
Lga,r
10 Calculation of the acoustic correction due to the room LA - in accordance with
Article A12.7e).
20 The noise level Lga,r was calculated with relationship Lga ,r  Lga  LA . The results
for the 63–8 000 Hz frequency bands are centralised in Table A12.10.
30 The permissible noise level requirement for ensuring acoustic comfort Lga,r shall be
verified, for all 1/1 octave frequency bands within the 63–8 000 Hz range, using relationship
Lga ,r  f   Lad  f  , for the noise curve Cz 30. Table A12.10 gives the values for curve Cz 30
within the 63–8 000 Hz frequency range; it must be noted that the covering requirement is
complied with.
Table A12.10
L
Calculation of the aerodynamic noise level transmitted to the reception point ga,r
1
2
3
4
5
6
7
8
9
Frequency f (Hz)
63
125
250
500 1000 2000 4000 8000
Noise level produced by air passing
27.9 26.9 27.9 26.9 25.9 22.9 17.9 12.9
through anemostats Lga (dB)
Acoustic correction LA (dB)
Noise level Lga,r (dB)
-14
-14
-13
-13
-12
-12
-12
-12
13.9
12.9
14.9
13.9
13.9
10.9
5.9
0.9
Lad - CZ30 (dB)
60
50
42
36
30
27
25
24
g) Determination of the additional attenuation systems:
10 The additional attenuation Lnec required for all 1/1 octave frequency bands within
the 63–8 000 Hz range was determined with relationship
149

Lnec  L
aer
v ,r
 Lga ,r

 Lad  Lga ,r

 10 lg10 10  1 , [dB]




(A12.17)
and the results were centralised in Table A12.11.
20 Choosing the attenuation systems - a type R1 lamellar rectangular active attenuator
was chosen (Figure A12.11), with the following dimensional characteristics:
l  2,00 m
- length
g  100 mm
- lamella thickness
d  100mm
- distance between lamellae
The attenuation levels LR for the frequencies within the given range are entered in Table
A12.11, in accordance with the requirement for providing additional attenuation
LR  Lnec
Table A12.11
Dimensioning the additional attenuation systems
1
2
3
4
5
6
Frequency f (Hz)
63
125
250
500 1000
aer
68.9 64.4 61.9 57.9 52.9
Noise level Lv ,r (dB)
Noise level Lga,r (dB)
Lad - Cz 30 (dB)
7
2000
45.4
8
4000
38.9
9
8000
33.9
13.9
12.9
14.9
13.9
13.9
10.9
5.9
0.9
60
50
42
36
30
27
25
24
14.4
19.9
21.9
22.9
18.4
13.9
9.9
16
26
40
56
74
67
50
Attenuation level required Lnec (dB) 8.9
R1 lamellar active attenuator LR (dB) 14
150