ICELANDIC NATIONAL CONCERT & CONFERENCE CENTRE IN REYKJAVÍK
ARTEC Project No. 3760
G. PERFORMANCE QUALITIES & DESCRIPTION OF SYSTEMS
ARTEC CONSULTANTS INC
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ICELANDIC NATIONAL CONCERT & CONFERENCE CENTRE IN REYKJAVÍK
NOISE CONTROL AND SOUND ISOLATION
INTRODUCTION
These guidelines are presented to assist the design team and cost estimators in making
performance spaces and other rooms in the facility appropriately quiet, while keeping noise
control costs moderate. These recommendations are based on both our wide experience and
standard noise control engineering practices.
THE NEED FOR LOW NOISE LEVELS
Noise is defined as unwanted sound. During a performance, any sound not produced by the
performer is, therefore, noise. Absence of noise is a prerequisite for excellent acoustics.
Unless background noise is reduced to the appropriate level, all of the other design work and
money spent to achieve good acoustics will be in vain.
Noise and vibration control must begin at the outset of the project. The purpose of minimizing
noise and vibration is not simply to reduce annoyance to the performers or audience; the
motivation reaches much further. Very low background noise levels are vital to:




Maximize the clarity and richness of the sound
Provide ease of concentration and communication among performers
Maximize the audible dynamic range
Maximize the length and apparent loudness of the reverberant sound as it dies away
BACKGROUND NOISE CRITERIA
In order to achieve an appropriate acoustical environment, design goals for noise and vibration
will be stringent. Criteria will be developed for mechanical/electrical systems as well as for
outside noise. Throughout the rest of this report we refer to “noise-critical spaces.” These are
spaces where special precautions must be taken in the design of building systems, and in the
structural and architectural design to satisfy the appropriate criteria. These “noise-critical
spaces” include performance, rehearsal, teaching, and technical spaces many other areas where
quiet is required.
The criteria for allowable noise levels are presented in terms of Noise Rating (NR) curves
according to ISO R 1996 (1971) in octave bands from 63 Hz through 8 KHz. These curves
have been extended to include the 31.5 Hz octave band where values are limited to a
maximum of 65 dB to prevent possibility of any perceptible vibration in walls or ceilings built
from lighter construction. The A-Weighted sound level (dBA) corresponding to each NR
curve is also provided for reference only; it is the octave band levels that will need to be met in
the finished building.
For the Concert Hall, we are recommending a background noise level which approximates
NR0, but it is not as stringent in the low band; this criteria is referred to as N-1. The octave
band sound pressure levels for the noise criteria are given in the following table. All values
are in dB (ref: 20 μPa).
Criterion
N-1
NR10
NR15
NR20
NR25
NR30
63
36
43
47
51
55
59
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125
22
31
35
39
44
48
OCTAVE BAND CENTER FREQUENCY (HZ)
250
500
1K
2K
4K
13
8
5
3
3
21
15
10
7
4
26
20
15
12
9
31
24
20
17
14
36
29
25
22
20
40
34
30
27
25
8K
3
2
8
13
18
23
dB(A)
19
21
26
30
35
39
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NR35
NR40
63
67
53
57
45
49
39
44
35
40
32
37
30
35
28
33
44
48
BACKGROUND NOISE GOALS
The following table presents background noise criteria for each of the “noise critical spaces”
on the project.
SPACE DESCRIPTION
BACKGROUND NOISE GOAL
Concert Hall:
Concert Hall
Sound and Lighting Control Rooms – operable window
Sound and Lighting Control Rooms – fixed window
Announce/Observation Rooms
Broadcast/Recording Room
Simultaneous Interpretation Booths
Projection and Followspot Rooms
Orchestra Assembly Area (backstage)
Technical Offices
Rehearsal/Recital Hall:
Rehearsal/Recital Hall
Conference Hall:
Conference Hall
Sound/Lighting Control / Projection Rooms
Simultaneous Interpretation Systems Booths
Followspot Rooms
Break-Out Conference Rooms
Exhibition Area
Performer Spaces:
Conductor Dressing Room
Soloist and Concert Leader Dressing Rooms
Musician Rehearsal/Storage Rooms
1-2 person Dressing Rooms
Orchestra Dressing Rooms
Conference Space Dressing Rooms
Administrative Areas:
Administrative Offices
Conference Rooms
Administrative Offices (Open Plan)
Common Areas:
Lobby & Public Lounges
N-1
NR 10
NR 15
NR 15
NR 15
NR 15
NR 20
NR 15
NR 30
NR 15
NR 20
NR 25
NR 15
NR 30
NR 30
NR 35
NR 20
NR 25
NR 25
NR 25
NR 30
NR 30
NR 30
NR 30
NR 35
NR 35
Except for special circumstances, occupied spaces not listed here should meet NR 40, or
otherwise fall within the limits of local environmental requirements.
The above criteria is intended to guide the design of mechanical systems. Criteria for sound
isolation between spaces, from electrical and outside noise will not necessarily be the same as
the criteria given for mechanical background noise. Transient, intermittent and tonal noise
sources will be addressed with criteria that can more accurately gauge audibility and
annoyance.
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ARCHITECTURAL CONSIDERATIONS
Sources of Noise and Vibration
Noise and vibration can arise from sources both inside and outside a building. In the initial
stages of design, the architect and design team should be aware of all of the following noise
sources:
Internal sources
 Elevators, escalators
 People and equipment in bars and foyers
 Scenic construction
 Loading activities
 Restaurant activities
 Electrical transformers
 Panel and relays
 Lighting fixtures
 Mechanical and electrical systems
External sources




Water
Thunder and rain
Outdoor events
Road, air and boat traffic
FACILITY PLANNING AND DESIGN FOR ACOUSTICAL ISOLATION
General Requirements for Airborne Noise Isolation:
Requirements for airborne noise isolation will be dependent upon the planned uses of any
specific space, its corresponding background noise criteria, and specific adjacencies. Specific
criteria will be developed during early design phases and stated as R’w values in dB in
accordance with ISO 140-4, 140-5 and 717-1. Alternative methods to ensure sufficient
airborne sound insulation at lower frequencies, such as C50-5000 according to ISO 717-1, will
also be evaluated during design.
In general, horizontal airborne sound reduction shall be minimum R’w = 51dBexcept where
identified elsewhere in this document. Please note that for certain noise sensitive and/or noisy
areas such as plantrooms there will be a demand for significantly higher degree of airborne
sound insulation (up to R’w = 70 dB). Particular attention is to be given to low frequency
sound transmission and sound flanking paths between adjacent spaces, particularly music
performance and rehearsal spaces.
In office areas, airborne sound insulation of the partition walls, excluding doors, should
generally be minimum R’w = 44 dB between adjacent offices, and R’w = 40 dB between the
office and adjacent corridors. No specific acoustical criteria will be given for doors to
standard offices.
In meeting rooms and executive offices, the airborne sound insulation between adjacent spaces
shall be minimum R’w = 48 dB, and R’w = 44 dB between these spaces and adjacent
corridors. Doors should achieve minimum R’w = 31 dB for these areas.
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In technical control rooms within performance spaces, airborne sound insulation between the
control room and performance space should generally be minimum R’w = 54 dB. Doors
leading into these areas should achieve minimum R’w = 35 dB, depending on location.
Specific attention to vision glazing will be required in these rooms.
General Requirements for Outdoor Noise and Vibration:
A complete noise and vibration study of the site will be prepared early in the design phase, and
will include expected auto and ship traffic load, as well as other expected noise sources. This
will be used to develop sound insulation criteria for facades, exterior glazing, and roof
structures.
The earliest stages of design allows for considerable opportunity to anticipate and avoid
acoustical isolation problems. Some of the required isolation can be achieved by careful
planning of the spaces in and around the building. The success of this early planning will have
a significant effect on the overall cost of the building.
Some General Planning Considerations:




Performance/rehearsal spaces should be surrounded, vertically and horizontally, by
program spaces like foyers, lobbies, offices, storage spaces, backstage areas, etc so their
exposure to the exterior environment is minimized.
Place no mechanical or large electrical equipment in these surrounding rooms.
Do not attach plumbing fixtures and pipes to the walls, floor or ceilings of any
performance or rehearsal space.
Locate the noisiest spaces farthest from the performance spaces.
Locations of WC
The noise caused by water flow from flushing toilets is audible in some existing performance
and rehearsal spaces. Avoid locating WC’s directly adjacent to the performance or rehearsal
spaces. Across a corridor is acceptable.
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Sound and Light Locks
Sound and light locks are essential for all entrances to and exits from performance and
rehearsal spaces. This is to provide an appropriate sound (and light) isolation buffer between
the performance/rehearsal venue and its surrounding areas.
A sound and light lock consists of two sets of doors with at least 1.5 m separation, forming a
small vestibule. All walls forming a sound and light lock walls are to extend from floor slab
to ceiling slab, and are to be sealed airtight to all surrounding construction. Typical sound and
light locks should incorporate heavy doors with a minimum sound class of 35dB; either 55
mm thick solid wood or insulated steel doors fitted properly in frames with full perimeter
sound gasket.
STRUCTURAL CONSIDERATIONS
Structural Design and Acoustical Isolation
To ensure maximum viability of the facility, it is important that the major performance venues
can operate concurrently with each other and with the conference facilities. To reduce the
possibility of noise transmission through the building structure, it is important to structurally
separate the concert hall, recital hall, and conference hall from each other and the rest of the
facility with a 50mm wide structural separation. This break will occur from foundations up
through the roof.
Artec will work with the design team as facility massing is being planned to develop these
structural breaks in the most cost effective manner – often in cooperation with necessary
building structural movement joints.
Locations for the Mechanical & Electrical Equipment Buildings
To keep air-borne and structure-borne noise out of noise-critical areas, major mechanical and
electrical equipment should be centralized in locations remote from noise-critical spaces.
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Plan for a structurally separate physical plant that will house the heaviest, noisiest equipment,
such as chillers, pumps, and large fans. This physical plant should also be planned to house
major electrical equipment such as distribution switchgear and transformers. All this
equipment should be located on grade.
Satellite mechanical and electrical plantrooms should be minimized in quantity, located
remote from noise critical areas, and should only contain fan units (not contain large
machinery such as chillers or large pumps or large transformers). Isolating construction of
walls and slabs will depend largely on the location of these spaces, so it is advisable to keep
these areas remote from sensitive areas, surrounded by similar spaces where noisy activities
occur, and on grade where possible to avoid expensive sound isolating constructions.
Mechanical and electrical duct shafts and duct zones can be used as acoustical “buffer zones”
around the mechanical equipment room. Each duct or shaft that penetrates the plantroom
enclosure must be sealed appropriately.
Doors to and from plantrooms should lead only to acoustically non-critical building areas. In
some special cases sound locks or special acoustical doors may be required at access doors to
the plant rooms.
Fresh air intakes and exhaust air discharges should be planned to not lead onto noise sensitive
outdoor areas or onto locations where noise can re-enter the building through walls, windows,
doors or vents.
MECHANICAL SYSTEMS CONSIDERATIONS
Air Handling Systems Serving Noise-Critical Spaces
The degree of noise control materials and methods used to properly attenuate noise produced
by the air delivery systems will depend on a number of factors, but among the most important
is the length of acoustically lined duct between the fan and the nearest terminal in the noisecritical space. Significant savings can be had if the system is laid out so that there are no
particularly short duct lengths. We therefore advise that air handling units serving noisecritical spaces be located as remote from the spaces they serve as possible to facilitate these
long duct runs.
A combination of vibration isolators, duct silencers, insulated acoustical plenums, insulated
fan casings, and careful duct routing will also be used to attenuate the noise from these
systems.
The Need for Separate Air Handling Systems
It is strongly advised that all main performance/rehearsal spaces be served from dedicated
constant volume air handling systems to achieve consistency in background noise levels and to
allow flexibility and cost-efficiency in the operation of the facility.
In addition, there are several areas where, because of operating schedules and load variations,
air handling systems must be operated (not just controlled) independently of the systems
serving the performance areas. These include:

Rehearsal spaces

Box office(s)

Technical control rooms, followspot rooms, projection rooms (these several spaces may be
separate zones on one system, but not on the audience chamber or lobby systems)

Instrument storage rooms
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These rooms should be served by air handling units located in the mechanical plantroom,
independent of the halls. This arrangement will allow the technicians, staff and artists to work
in the control rooms during “off”-hours without the necessity of running the main mechanical
systems for the halls.
In most cases, one or more of these rooms can be served by one air handling unit, if feasible
from an engineering standpoint. Systems can be VAV if feasible.
Lighting, sound and communications equipment can sometimes remain on 24 hours a day and
can generate a lot of heat. Therefore a separate, dedicated air-handling unit(s) for the spaces
housing this equipment is advised. The air handling unit can be located in the equipment
rooms in most cases.
Some areas may require separate air handling systems for health reasons as well as time of use.
These include:

The receiving dock, where toxic fumes are encountered (for exhaust of truck fumes as well
as for dust reclamation)

Film Projection Rooms (depending on specific code requirements)

Follow spot rooms (certain types of follow spots emit toxic fumes)

Treat this equipment as discussed above to keep noise and vibration from noise-critical
spaces.

Spaces with noise criteria of NR 25 and higher can be served through variable air volume
(VAV) systems. Care must be taken to locate VAV boxes serving each room to achieve
the desired criteria in the particular room.
Acoustical Lining
Mineral wool or glass fiber duct lining insulation (density 24–48 kg/m3) with integral
protective facing will need to be installed in all ductwork systems serving noise-critical spaces.
Acoustical duct lining insulation typically should be 25 mm thick installed in all ductwork
serving noise critical areas. Final lining requirements will be developed when duct layout and
equipment selections have been made. Additional thermal insulation is not usually required
for acoustically lined ducts.
Acoustical Plenums and Duct Silencers
Control of low-frequency fan noise is often best achieved through a combination of duct
silencers and acoustical plenums. Plenums can be built on site from concrete, block, or
prefabricated insulated steel panels.
Assume all acoustical plenums will be internally lined with duct liner insulation (100 mm
thick, typical).
For initial pricing, planning and mechanical room layout assume that each of the supply and
return systems serving any space with a noise criteria of less than NR 20 will require a plenum
on the order of 2.0m × 3.0m× 3.7 m.
Duct silencers may be required for noise attenuation when the noise reduction from
acoustically lined duct is not sufficient. For initial pricing, planning, and layout, assume that
each supply and return system for spaces with criteria of NR 15 or less will each need a 3 m
long silencer. Each system serving spaces with criteria of NR 20 will require a 2m silencer,
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and each system serving spaces with criteria between NR 20 – NR 30 will require a 1 m
silencer.
It is recommended to install silencers where the ducts exit the mechanical plantroom. The
heavier gauge steel from which silencers are built acts to reduce mechanical room noise breakout. Also, regenerated noise from silencers, even when the silencers are correctly located,
means that they should be located as far from the terminals as possible.
Duct Materials and Duct Geometry
Rectangular sheet metal duct should be used for most applications. Avoid duct dimensions
with aspect ratios exceeding 4:1, as they have a tendency to drum.
If exposed ductwork is required inside a noise-critical space (quiet or noisy), use internally
lined circular duct, since this shape allows less noise to break into or out of the duct. Do not
use circular ducts for general use since they do not attenuate low frequencies sufficiently.
Transitions in duct geometry should be gradual; none greater than 1 in 7.
Elbows
Use full radius elbows in systems serving noise-critical spaces in order to minimize generation
of low frequency turbulence. Where full radius elbows are not possible, small radius elbows
are still preferable to mitered elbows. Do not use turning vanes, except where required within
the mechanical room or far away from the terminal outlets as they generate turbulence noise.
Control Systems in the Critical Spaces
Control systems located in noise-critical spaces must be electronic and must operate silently.
Direct location of these devices within the space should be avoided if possible.
Routing of Ducts and Pipes
Routing of ducts and pipes should be carefully considered early in the design. Avoid service
penetrations in sound isolating constructions wherever possible. Ducts and pipes should not
enter noise critical spaces directly from another occupied program space, but rather from an
enclosed, quiet duct space or shaft.
Do not route ductwork serving noise-critical spaces through noisy spaces or through other
noise-critical spaces. Noise can enter the duct in one space and be transmitted down the duct
to another.
Piping and Noise-Critical Spaces
Hot water, chilled water, domestic water, steam, sanitary, or roof drain piping should in
general not be run within or through noise-critical spaces. Hot water and steam pipes can
generate noise as the pipes expand and contract in the pipe clamps and as valves constrict the
flow. Pipes connected to pumps will vibrate and radiate low frequency pump noise as well as
flow noise. Such vibration can easily be transmitted through the building structure.
Flow noise can be a problem in all pipes, including domestic hot and cold water. This can be
minimized by sizing pipes for a maximum velocity of 1.2m/s for pipes 50mm in diameter or
less and 3m/s for larger pipe sizes using a pressure drop limitation of 400 Pa/m. Flow noise
and vibration can also be introduced by turbulent flow, sharp pressure losses and trapped air.
Care should be taken to avoid these conditions.
Sprinkler pipes pose no acoustical problem in quiet spaces, but the points where they penetrate
the envelope of any noise- critical space must be carefully sealed.
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Roof drain pipes transmit noise from outside and also radiate flow noise in storms.
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Controlling Air Flow Noise
Noise is generated by the flow of air through or past diffusers, grilles, dampers, turning vanes,
and duct fittings. The sound power generated at any one location depends on both the air
velocity and the local geometry. The greater the air turbulence, the greater the sound power
generated; higher velocities in the presence of local obstructions result in greater turbulence
and therefore higher noise levels.
Air Supply From Underfloor Plenum
One method of air delivery in the Concert Hall is to supply air through a plenum under the
concrete slab(s) supporting the seating and delivering the air through holes/outlets in the floor
coordinated with the audience seating. This approach will require coordination with seating,
structural considerations, and careful design of duct distribution and terminal outlets to ensure
even distribution of air to all areas of the auditorium.
Underfloor Plenum
For initial pricing purposes, assume all walls and ceiling of the distribution plenum under the
floor slab are lined with glass or mineral fiber duct lining insulation (50 mm, typical).
Air Velocities in the Ducts Leading to the Plenum
When providing air supply through a large underfloor plenum, the following air velocities
guidelines are recommended:
SUPPLY AIR VELOCITY – UNDERFLOOR SYSTEM ONLY
at face of terminal device†
0.3 m/s to 0.5 m/s or approx. 9 to 12 L/s per seat
Distribution duct in plenum (if necessary) 1.3 m/s - 2.5 m/s
riser duct outside of plenum
3 m/s to 4.6 m/s depending on location
†Note: Velocity through hole in floor slab may be higher than at face of pedestal.
Conventional “Top Down” Systems For Performance Spaces
If an underfloor air supply system is not desirable, then delivering the air from the ceiling and
returning at low level is the other common approach. To deliver air quietly and minimize very
low air velocities throughout the system with this approach, it is important to remove the
noise-generating obstructions and provide gradual transitions in velocity.
For this type of system to operate silently, the duct termination must be free from all
obstructions. With no obstructions at the terminal outlet, smooth velocity transitions, and
sufficient length of lined ductwork to attenuate turbulence noise, we can allow the velocities to
be higher throughout the system.
The following air velocity guidelines are recommended for the design of the air distribution
systems throughout the facility.
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Table 4 Air Velocity Guidelines
Location
at terminal outlet
to 7 diameters
distribution
ductwork in room
Main header ducts
in space
maximum outside
room
In Plantroom
Location
Inlet condition
to 7 diameters
distribution
ductwork in room
Main header ducts
in space
maximum outside
room
In Plantroom
Guidelines for Supply Air Velocity in fpm (m/s)
Design Noise Goal for Space
N-1
NR 10
NR 15
NR 20
400 (2.0)
500 (2.5)
550 (2.8)
600 (3.0)
450 (2.25)
550 (2.8)
600 (2.8)
650 (3.3)
600 (3.0)
700 (3.5)
750 (3.8)
800 (4.0)
NR 25
650 (3.3)
700 (3.6)
850 (4.25)
NR 30
700 (3.5)
750 (3.8)
900 (4.5)
850 (4.25)
850 (4.3)
900 (4.5)
1000 (5.0)
1100 (5.5)
1100 (5.5)
1200 (6.0)
1250 (6.3)
1300 (6.5)
1400 (7.0)
1400 (7.0)
1500 (7.5)
1800 (9.0)
1800 (9.0)
NR 25
500 (2.5)
550 (2.8)
800 (4.0)
NR 30
600 (3.0)
650 (3.3)
900 (5.0)
1800 (9.0)
1800 (9.0)
1800 (9.0)
1800 (9.0)
Guidelines for Return Air Velocity in fpm (m/s)
Design Noise Goal for Space
N-1
NR 10
NR 15
NR 20
300 (1.5m/s)
350 (1.7)
400 (2.0)
450 (2.3)
350 (1.75)
400 (2.0)
450 (2.3)
500 (2.5)
600 (3.0)
650 (3.3)
700 (3.5)
750 (3.8)
850 (4.3)
850 (4.3)
900 (4.5)
1000 (5.0)
1100 (5.5)
1100 (5.5)
1200 (6.0)
1250 (6.3)
1300 (6.5)
1400 (7.0)
1400 (7.0)
1500 (7.5)
1800 (9.0)
1800 (9.0)
1800 (9.0)
1800 (9.0)
1800 (9.0)
1800 (9.0)
Controlling Mechanical Systems Vibration
It will be necessary to install mechanical equipment on vibration isolators, since structural
discontinuities cannot provide sufficient vibration attenuation at low frequencies. General
guidelines for space requirements are discussed in the following sections.
Equipment Location and Support
All major equipment should be located on grade.
When it is necessary to install smaller equipment on elevated levels, it must be positioned near
or directly above supporting columns or major beams. Suspended equipment should be
supported from beams, joists, or other relatively heavy structural members—members not
connected to the structure of the performance space.
Please note that it may be necessary to frame between major beams for additional support as it
is vital to make the supporting structure as stiff as possible. Locate vibration isolation mounts
directly on the building structure where possible. Avoid direct support from lightweight slabs
or roof decks, and avoid seating isolation mounts on steel frame sub-structures.
Space Requirements
Sufficient space is to be provided for mechanical equipment vibration isolation bases:
generally 50 mm minimum horizontal clearance between any vibrating equipment and nearby
building structure; and generally 50 mm between the underside of a loaded concrete inertia
base or structural base and the top of the concrete housekeeping pad or floor slab.
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The vertical requirements for vibration isolator hangers range from 100–300 mm, depending
on the size of the unit or pipe. Take isolator dimensions into account when considering piping
layout.
Housekeeping Pads
Provide reinforced concrete housekeeping pads (100 mm thick typically) below all large floorsupported mechanical and electrical equipment. Size this pad to extend beyond the supported
mechanical unit plus its vibration isolators. The pads provide local mass and stiffness below
mechanical equipment, and prevents debris from accumulating beneath the inertia base, which
would short out the isolators.
Inertia Bases
Spring-supported concrete inertia bases below mechanical equipment units are necessary for
the stability of most pumps; for equipment with a high center of gravity or with high
unbalanced forces during normal operation or starts and stops; and for some very noisy
equipment. Typical applications are large fans, medium to large base-mounted pumps, and air
compressors.
Inertia bases should be generally 150 mm thick and should weigh one to two times as much as
the equipment they support (including any associated piping, fluid, and/or dynamic loads).
Specific inertia base requirements will be determined on an individual basis after equipment is
selected.
Electrical Connections to Mechanical Equipment
Electrical connections to all vibration-isolated equipment including pumps, fans, and
transformers should be made with flexible conduit installed in a slack “U-shape”.
Duct Connections
Connect all ductwork to fans, fan casings or fan plenums with flexible sleeves.
Pipe Connections
Mechanical and plumbing pipes are to be supported on spring-and-neoprene hangers having
the same static deflection as the equipment to which the pipes are connected. These hangers
are required within the mechanical room. Outside the mechanical plantroom, chilled
water/glycol piping smaller than 50 mm should be supported on neoprene hangers or supports.
Support piping that is 50 mm and larger on spring and neoprene isolators.
Do not hang large diameter chilled water piping from structure common to the performance
spaces. Run these large, noisy pipes only in spaces that are inherently noisy i.e. mechanical
rooms, garage, and loading dock. Isolators alone do not provide adequate protection against
the high vibrational energy in such pipes.
Suspend pipes with outside diameters over 13 mm connected to fan coils with spring hangers.
This should allow the isolated fan unit to “float” freely on its mounts, avoiding strain on any
pipe connections.
Use flexible pipe couplings at or near connections to mechanical equipment. Such couplings
facilitate pipe alignment as well as providing some isolation.
Use flexible couplings where pipes cross vibration joints between separate structures. This
applies to all piping except sprinkler pipes. Details of the approach will be developed with the
engineers as the design progresses.
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All large pipes connecting the chilled water pumps, the cooling tower, and the chiller must be
fully isolated over their entire lengths with combination steel spring/neoprene isolators.
Fan Selection Criteria
We recommend Class I built-up centrifugal fans with backward-inclined airfoil blades for all
noise-critical systems. Selection and final balancing of fans for maximum efficiency is
critical, since a fan operating at a higher efficiency will be quieter. Axial and forward-curved
centrifugal fans are acceptable in some circumstances.
Pump Selection
For similar reasons, select and balance centrifugal pumps for maximum efficiency. Low pump
efficiency and small impeller-cutwater clearance tend to cause high pump noise and energy
transmission to the fluid and piping.
Chillers and Cooling Tower Selection
To minimize noise, hermetically sealed centrifugal chillers are recommended.
Cooling towers must not be mounted on structure that is common to noise-critical spaces.
Mounting cooling towers on a grade slab, structurally separate from the rest of the facility is
preferred. If the cooling tower is mounted on building structure, large spring isolators must be
used. Noise emission to surrounding neighbors will need to be considered, and mitigating
measures (enclosures) may be required.
ELECTRICAL SYSTEMS CONSIDERATIONS
Power Distribution & Transformer Location
Since electrical transformers of all sizes and electromechanical transducers are capable of
inducing vibration into the supporting structure and generating airborne noise, it is strongly
advised to plan for a main electrical equipment room or rooms where all power distribution
equipment will be located. This room (or rooms) should be in a part of the facility that is, like
the main mechanical equipment room, structurally separate from noise critical spaces. Also,
all main electrical equipment should be located on grade. Transformers larger than 45kVA
capacity should not be located above grade or suspended.
No major or minor transformers should be located outside an isolated mechanical structure.
High voltage distribution to multiple step-down transformers within the building is not
acoustically acceptable.
Dimmer Room
Dimmer racks for house and production lighting produce considerable noise and vibration and
will need to be located in an acoustically isolated dimmer room. Locate the dimmer room to
conserve electrical wiring while ensuring appropriate reduction of noise and vibration. Do not
position it directly over, under, or beside noise-critical spaces.
Separate rooms housing electrical equipment of this kind from critical spaces by heavy
masonry walls, intervening corridors, and storage rooms. If such buffer spaces cannot be
properly located, then multiple layers of built-up constructions may be necessary.
Do not locate the transformer serving the dimmers in the dimmer room (unless it is in the
basement in an isolated structure).
Ballasts for Fluorescent Fixtures
Fluorescent fixtures may be used for worklights (only) in the performance and connected
spaces. Use electronic ballasts for these fixtures.
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Fluorescent fixtures may be used in dedicated rehearsal spaces, but the ballasts for them must
be remotely located.
In control rooms and observation rooms, fluorescent fixtures may be acceptable with
electronic ballasts, or remote ballasts.
Low-Noise Dimmers
Artec will specify dimmers used with performance lighting, concert lighting, house lighting,
and rehearsal room lighting to minimize noise generated by the filaments.
House Light fixtures
Fluorescent and neon fixtures are unacceptably noisy for house light applications in the
performance space. In general, incandescent fixtures connected to high rise-time dimmers will
result in acceptably quiet conditions.
Cable Routing and Sound Isolation
Sound isolating walls can be compromised severely by chases or penetrations for electrical
trunking or conduit. Cable routes should not pass directly between noise-critical spaces or
from noisy to noise-critical spaces.
Many problems can be avoided if the design team carefully consider the cable routes at an
early design stage. The cable routes to and from the dimmer room must be considered with
particular care.
Emergency Power
Do not locate contactors for emergency lighting fixtures in noise-critical spaces. Such relays
are normally on and can generate disturbing hum.
Exit signs in performance and rehearsal spaces should not contain relays, transformers or
contactors, and must not be fluorescent. Incandescent line-voltage fixtures are acceptable.
Low voltage fixtures may be acceptable if all are fed by transformers located outside of the
noise-critical space.
Aisle Lights
We recommend incandescent line-voltage fixtures. Low voltage fixtures may be acceptable if
fed by transformers located outside of the noise-critical space.
ELEVATOR/ESCALATOR NOISE AND VIBRATION
Wherever possible, hydraulic elevators should be used as they operate quieter than their
traction drive equivalent. Electric traction drive elevator machines impart transient vibrations
to the structure, which must then be isolated from surrounding structure, whereas hydraulic
equipment can be supported on vibration isolators:

Locate machine rooms on grade.

Walls of equipment room should achieve minimum Rw’ = 55 dB to surrounding areas.

If the elevator machine room is on structure that is common with any noise-critical space,
the floor slab must be isolated from the surrounding structure. The equipment room floor
slab should be isolated from the walls and footings by a 50 mm wide acoustical expansion
joint.

For electrical elevators, since the floor cannot be tied into the building structure, the weight
of the floor slab itself must counterbalance the weight of the cab, the load, and the
counterweight. This must be addressed in the structural/architectural design.
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
Mount motor generators and other equipment on vibration isolators.

Pipe and conduit penetrations in the equipment room should be sleeved, packed and
caulked as with other penetrations of noise-critical walls.

Use manufacturer's standard polyurethane roller guides on the cab guide system to reduce
noise generated by cab movement.

For electrical elevators, isolate the head sheave from shaft structure with 2-direction
isolators. Artec will suggest a guideline detail, if necessary.

Make room in the basement for elevator machine rooms, and plan for underslung and/or
hydraulic equipment in the budget. Artec will advise on particular acoustical details later
in the project.
OTHER NOISE SOURCES
Interior activities such as kitchen commotion, set-ups for catered events, scenery handling, and
scenery construction can be significant sources of noise. Consideration must be given to the
locations and logistics of these activities so that they will not negatively impact the noisecritical spaces.
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