The Italian law on building acoustics
DPCM 5/12/1997
Angelo Farina
Dip. di Ingegneria Industriale – Università di Parma
Parco Area delle Scienze 181/A, 43100 Parma – Italy
farina@aidasrl.it
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D.P.C.M.
5 December 1997:
Titled:
Specification of acoustical passive performances of buildings
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D.P.C.M.
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5 December 1997:
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D.P.C.M.
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5 December 1997:
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D.P.C.M.
5 December 1997:
Triv
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D.P.C.M.
5 December 1997:
Summary: 5 acoustical requisites for buildings:
1.Facade sound insulation
2.Apparent sound reduction index of internal partitions
3.Normalized tapping noise level
4.Maximum “slow” SPL of discontinuous equipment
5.Leq of equipment in continuous operation
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Facade Sound Insulation
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Facade Sound Insulation (2):
D.P.C.M. 5/12/1997 – Annex A
The Standardized Facade Sound Insulation (D2m,nT), is defined by:
D2 m,nT  D2 m
T 
 10 log 
 T0 
D2m = L1,2m – L2 is the SPL difference
L1,2m = SPL measured 2m far from the facade, caused by traffic noise, or by a
loudspeaker, with an incidence angle of 45°;
L2 = average SPL inside the receiving room;
T = reverberation time inside the receiving room, in s, (ISO 3382 standard);
T0 = reference reverberation time, equal to 0.5s;
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Facade Sound Insulation (3):
D.P.C.M. 5/12/1997 – Alnnex A
The average SPL in the receiving room, L2, is computed with this formula:
Li
1 n

L2  10 log  1010 
 n i 1

Li are measurmenets performed in a number n of points. n is the integer number
just above 1/10 of the room’s volume, in cubic meters. In any case, the minimum
value for n is 5.
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Facade Sound Insulation (4):
D.P.C.M. 5/12/1997 – Annex A
NOTES:
a.
The ISO 3382-1975 standard (reverberation time) was subsequently updated
in 1997 and in 2008;
b.
The DPCM does not specify that the volume of the receiving room has to be
expressed in cubic meters;
c.
The quantity denoted D2m,nT is defined in UNI EN ISO 140-5 as normalized
facade insulation (and not “standardized”);
d.
The UNI 8270 standard, defining the single-number rating of facade
insulation, has been superseded by UNI EN ISO 717/1.
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Facade Sound Insulation (5):
Norma EN ISO 717-1:1997
Single-number rating
For getting a single number giving the weighted normalized facade insulation,
D2m,nT,w, the following procedure must be followed.
The ISO 717 reference spectrum must be moved down, with 1dB steps, over the
measured spectrum of D2m,nT.
At each step, the sum of unfavorable deviations is computed (an unfavorable
deviation occurs when the measured value, at a frequency band, is below the
corresponding vale on the reference curve).
When the sum of unfavorable deviations becomes smaller than 32, the reference
curve is properly positioned.
The weighted normalized facade insulation, D2m,nT,w is defined as the value of the
reference curve at the frequency of 500 Hz.
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Facade Sound Insulation (6):
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Sound insulation of internal partitions
Attention!
Only partitions between two
different properties are
subjected to the law!
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Sound insulation of internal partitions (2):
D.P.C.M. 5/12/1997 – Allegato A
NOTES:
a.
The apparent sound reduction index R’ is defined by the EN ISO 140-4:2000
(and NOT by EN ISO 140-5:1996, as incorrectly written in the DPCM).
b.
The UNI 8270 standard, defining the single-number rating of facade
insulation, has been superseded by UNI EN ISO 717/1.
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Sound insulation of internal partitions (3):
EN ISO 140-4:2000 standard
Sound Insulation, D: Diffrence, in dB, between the spatially and temporally
averaged values of the SPL in the two rooms:
D  L1  L2
L1 is the average SPL in the transmitting room;
L2 is the average SPL in the receiving room.
The apparent sound reduction index, R’ is given by:
S
R'  D  10 log 
 A
where:
D is the Sound Insulation;
S is the area of the wall separating the two rooms;
A is the equivalent absorption area of the receiving room.
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Tapping Noise (4):
EN ISO 140-4:2000 standard
The equivalent absorption area of the receiving room, A, is computed as:
A  0.16
V
T
where:
V is the volume of the receiving room, in cubic meters;
T is the reverberation time measured inside the receiving room.
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Sound insulation of internal partitions (5):
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Tapping Noise
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Tapping Noise (2):
D.P.C.M. 5/12/1997 – Annex A
NOTES:
a.
The normalized tapping noise level (L’n), is defined by the UNI EN ISO
140-7:2000 stndard, instead of EN ISO 140-6:1996, as written in the DPCM.
The latter is for laboratory measurments, whilst the DPCM is referring to “in
situ” measurments.
b.
The UNI 8270 standard, defining the single-number rating of normalized
tapping noise level, has been superseded by UNI EN ISO 717/2.
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Tapping Noise (3):
UNI EN ISO 140-7:2000 standard
Average tapping noise level, Li: is the average SPL measured inside the
receiving room when the standardized tapping machine is operating inside the
adjacent room.
Normalized tapping noise level, L’n: it is the average tapping noise level
corrected by a term taking into account the equivalent absorption area of the
receiving room, with reference to a standard absoprtion area A0:
 A
L' n  Li  10 log 
 A0 
where:
A0 = 10 m2.
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Tapping Noise (4):
UNI EN ISO 140-7:2000 standard
The equivalent absorption area of the receiving room, A, is computed as:
A  0.16
V
T
where:
V is the volume of the receiving room, in cubic meters;
T is the reverberation time measured inside the receiving room.
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Tapping Noise (5):
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HVAC and plumbing noise
• The measurement is to be performed inside a different room (of a
different owner) than the one where the equipment is operating
• An explanation form the Ministry clarifies that the limit values are
those reported in table B.
• The “general limits” of 35 e 25 dB(A) contained in the descriptive
part of the DPCM are just a “lapsus calami” and are valueless.
• The noise produced by common (condominial) equipment are NOT
subjected to the differential limits given by DPCM 14/11/1997
“Determinazione dei valori limite delle sorgenti sonore”
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Tricks (facade insulation):
Interrupted gasket:
Isolamento di facciata
Vetro “SANCOPHON 6/12/4+4 Acustico”
(D2m,nT,W = 37dB)
45
40
D2m,nT (dB)
35
30
Isolamento
di facciata
25
Curva di
riferimento
20
15
3150
2500
2000
1600
1250
800
1000
630
500
400
315
250
200
160
125
100
10
Frequenza (Hz)
Isolamento di facciata
Vetro “SANCOPHON 6/12/4+4 Acustico” + bordo di cartongesso
(D2m,nT,W = 36 dB)
45
40
30
Isolamento
di facciata
25
Curva di
riferimento
20
15
3150
2500
2000
1600
1250
1000
800
630
500
400
315
250
200
160
125
10
100
D2m,nT (dB)
35
Frequenza (Hz)
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Tricks (facade insulation):
Continuous gasket:
solamento di facciata
Vetro “SANCOPHON 6/12/4+4 Acustico”
(D2m,nT,W = 42dB)
55
50
45
35
30
25
20
15
3150
2500
2000
1600
1250
1000
800
630
500
400
315
250
200
160
125
10
100
D2m,nT (dB)
40
Frequenza (Hz)
Isolamento acustico normalizzato rispetto al tempo di riverberazione
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Curva di riferimento
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Tricks (facade insulation):
Bad sealing around the frame of the window:
dB
D2m,nT,w = 37
"Isolamento Facciata"
Indice di valutazione dell'isolamento acustico standardizzato di facciata (D2m,nT,w = 37 dB)
55
50
D2m,nT (dB)
45
37
40
35
30
25
20
15
50
63
80
100
125
160
200
250
315
400
500
630
800
1000 1250 1600 2000 2500 3150 4000 5000
Frequenza (Hz)
Curva di riferimento norma ISO 717-1
Curva dell'isolamento acustico standardizzato di facciata normalizzato rispetto al tempo di riverbero
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Tricks (facade insulation):
Good sealing around the frame of the window:
D2m,nT,w = 41dB
"Isolamento Facciata"
Indice di valutazione dell'isolamento acustico standardizzato di facciata (D2m,nT,w = 41 dB)
55
50
41
D2m,nT (dB)
45
40
35
30
25
20
15
50
63
80
100
125
160
200
250
315
400
500
630
800
1000 1250 1600 2000 2500 3150 4000 5000
Frequenza (Hz)
Curva di riferimento norma ISO 717-1
Curva dell'isolamento acustico standardizzato di facciata normalizzato rispetto al tempo di riverbero
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Psychoacoustic effect
Complaints for low insulation (R’w = 45 dB)
After rebuilding the partition: R’w = 53 dB,
But the residents still complain….
Indice del potere fonoisolante apparente di partizioni tra ambienti (R'w = 53 dB)
70
65
60
53
55
R' (dB)
50
45
40
35
30
25
20
15
50
63
80
100 125 160 200 250 315 400 500 630 800 1000 1250 1600 2000 2500 3150 4000 5000
Frequenza (Hz)
Curva di riferimento
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Curva del potere fonoisolante apparente
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