REi

INITB) STATES 'ARTMENT OF MMERCE

IBLICATION

i'^ K. J&

NBS TECHNICAL NOTE 710-2

BUILDING

RESEARCH TRANSLATION

An Investigation of the

Protection of Dwellings

From External Noise

Through Facade Walls

U.S. 'ARTMENT

OF

OMMERCE

National

Bureau

IOO

1)57*3

H7V
NATIONAL BUREAU OF STANDARDS

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8 Part of the Center for Radiation Research.
National Bureau of Standards JW * 7 1972

UNITED STATES DEPARTMENT OF COMMERCE

Peter G. Peterson, Secretary

Ur NATIONAL BUREAU OF STANDARDS • Lewis M. Branscomb, Director A1^

NBS TECHNICAL NOTE 710-2

ISSUED MARCH 1972

Nat. Bur. Stand. (U.S.), Tech. Note 710-2,26pages (Mar. 1972) CODEN: NBTNAE

BUILDING RESEARCH TRANSLATION

An Investigation of the Protection of Dwellings

From External Noise Through Facade Walls

P. Gilbert

Centre Scientifique et Technique du Batiment

Paris, France

TRANSLATED FROM THE FRENCH BY:

Building Research Station Ministry of Public Buildings

and Works

United Kingdom

.<°'c0)

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature.

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402. (Order by SD Catalog No. C 13.46:710-2). Price 35 cents
FORE'

The United States/French Cooperative Program on Building

Technology entails an exchange of personnel between the

National Bureau of Standards (Building Research Division)

and the Centre Scientifique et Technique du Batiment

(CSTB) of France. The program also involves the exchange

of information between the two research organizations.

It is felt that some of the documented information can

be usefully shared with the U.S. building industry; and,

therefore, certain papers were selected for reproduction

in media on sale to the public by the Government Printing

Office. It should be understood that the CSTB documents

made public through such media as this TECHNICAL NOTE

do not necessarily represent the views of the National

Bureau of Standards on either policy or technical levels.

At the same time, building researchers at the National

Bureau of Standards consider it a public service to share

with the U.S. building industry certain insights into

French building technology.

O/JAMES R. WRIGHT

Chief, Building Research Division

Institute for Applied Technology

National Bureau of Standards
AN INVESTIGATION OF THE PROTECTION

OF DWELLINGS FROM EXTERNAL NOISE

THROUGH FAQADE WALLS

by

P. Gilbert

This paper is translated from the French original

and is published under the Building Research Division/

Centre Scientifique et Technique du Batiment information

exchange program.

An investigation was conducted to determine to what

extent the installation of balconies and loggias at

various angles of elevation from a noise source could

improve the sound insulation of a facade wall. Measurements of the sound pressure level were first carried

out on two types of facade, one incorporating traditional

window joinery and the other incorporating sealed glazing.

Following this, the sound insulation provided by facades

fitted with open and closed balconies and loggias (with

and without sound absorbent materials applied) was determined and compared with the previous measurements.

It was found that for angles of elevation greater than

30° , both the closed balcony and the loggia fitted

with absorbent materials appreciably improve the

sound insulation, whereas the open balcony does not.

Key words: Facade; noise; sound insulation; sound

pressure level; walls.
1. Purpose of the Investigation

In the last few years dwellings have been subjected to endlessly

increasing amounts of external noise due to road traffic, aircraft, etc.

It is extremely difficult to achieve sufficient attenuation of

intense noises by the facade wall of a block of flats in order to ensure

that the internal environment within the building shall be acceptable.

There are two reasons for this:

1. Lightness and rigidity of window glazing limits sound

insulation of the facade to a relatively low value.

2. Windows are frequently left open during a large part

of the year, thus reducing the sound insulation of the facade

to zero.

The investigation reported in this paper was undertaken in order to determine to what extent such items as balconies and loggias could

improve the sound insulation of a facade.

When the external noise level is known, a knowledge of the insulation

value of the facade enables the internal noise level to be determined and

1 / its compatibility with the requirements of the occupants to be assessed. —' In general, it will be found that an acceptable noise level at a noisy

location can only be achieved with closed windows. This gives rise to

a thermal comfort problem.A' However, one can also determine the acoustic

environment in which it is permissible to build with ordinary facades.

This investigation has been made possible by the financial support

of the "Delegation generale a la Recherche scientifique et technique" as part of the concerted activity of Plan IV within the field of building

and civil engineering.

2. Arrangement for Measuring the Sound Insulation of a Facade

An end wall of the new C.S.T.B. acoustic laboratory has been

specially fitted out for making the measurements.

The two rooms on the upper story, the openings of which can be seen

in the photograph in figure 1, are the measuring rooms.

The openings can be fitted with various types of windows and glazed

doors. Bolts are fitted enabling balconies and loggias to be attached

to the facade.

The area in front of the building is asphalted and marked out with

coordinates. A mobile tower carrying the noise sources can be moved

about over this area. 1/Cahiers 762; Volume No. 88; C.S.T.B.; October 1967 and Cahiers 871,

Volume No. 100; June 1969 UCahiers 608; Volume No. 72; C.S.T.B.; February 1965
3. Method of Measurement

The measurements were carried out on two types of facade, one incorporating traditional window joinery, the other incorporating sealed

glazing. The purpose of these measurements was to investigate the effect

of:

1. The angle of incidence of sound waves, characterized by the

angles of elevation (<J>) and azimuth (y) defining the direction

of arrival of the sound waves at the center of the facade

(figure 2). The angles 4> and y were given the values 0, 30,

60 and 80 degrees. In the case where the noise-source is

higher than the center-point of the facade was not examined.

2. The presence of balconies and loggias, with and without

absorbent material.

Some data were also obtained on the effect of glass thickness and

the air-tightness of windows on the sound insulation obtained. For a given incidence (<}> , y) of sound waves arriving freely at the facade, the

normalized sound insulation has, for the purposes of this investigation,

been taken as:

D = L - L +10 log(T/0.5) dB n I pr

where:

LT is the sound intensity level of the waves incident on the facade.

L is the reverberant sound pressure level within the room behind

pr the facade.

T is the reverberation time measured in this room.

The method of measurement follows directly from this definition.

A loudspeaker directed towards the center of the facade (figure 3)

is placed at a distance d from this point, this distance being considerably

greater than the dimensions of the facade wall. At this distance, the

loudspeaker produces a sound level, the value of which is known from a preliminary free-field calibration.

The reverberant sound pressure level in the test room is measured

while the loudspeaker is operating at incidence (<f> , y) and at a distance

d from the center of the facade. This interior measurement is made using

a microphone that is in continuous motion inside the room (figure 4)

,

being mounted on an arm which rotates about an inclined axis. This

arrangement enables the quadratic mean sound pressure to be determined.

The values L-j-, Lr)r , and T are measured and the value of the normalized

sound insulation, Dn , is deduced from them.

3
Precautions had to be taken to minimize the reflection from the

ground since this caused sound waves to arrive at the wall with a different

incidence, and these reflected waves could interfere with the direct waves.

It was mainly due to the directional properties of the loudspeakers used

that we were able to reduce the amplitude of the reflected waves suffiiently.

4. Description of the Types of Facade Used in This Investigation

The facades studied were those of two second-floor test-rooms

(figure 1). They were 3.30 m wide by 2.50 m high. The total area of each

facade occupied by windows and doors was almost exactly 3.6m , or 44% of

the total area of the facade. The test room dimensions were 3.30 x 2.50 x 4.25 m, giving a volume of 34 m . The facade wall had an overall thickness

of 25 cm, being built of 20 cm hollow blocks with a 2.5 cm mortar rendering

on each face.

(A) Facade with traditional joinery.

The windows and glazed doors were of traditional design, timber

framed and glazed in the usual way with 2.9 mm thick glass. The

windows opened inwards in the French manner.

Their dimensions were:

Total Hei ght Height of Total Width between

of Opening Reveal Width Reveals

cm cm cm cm

Door 228 225 86 80

Window 138 135 146 140

Except where otherwise stated in the results, this facade had

weatherstripping fitted to improve its air-tightness so that the

effect of the glazing could be assessed more easily.

(B) Facade with sealed glazing.

The second type of facade was one in which the openings, instead

of being closed in the traditional manner, were closed by 10 mm

thick sheets of glass sealed directly to the masonry.

The dimensions of the glazed areas were:

Door - 226 x 79 cm

Window - 134 x 138 cm
Sealed glazing of this kind is a rather unusual arrangement.

It was used because it provides the maximum degree of air-tightness,

thereby giving an insulation value that is due solely to the layer

of glass and is unaffected by an imperfectly controlled degree of

sealing against the passage of air.

Measurements were first made on these two facades in their

bare state. This was followed by measurements on the same facade

fitted successively with open balconies (balconies with open-work

guard-rails); closed balconies (i.e. with their guard-rail spaces

filled in) ; with loggias ; and finally with each of the above

arrangements of balconies or loggias but with the addition of

acoustic absorbent material affixed to their internal surfaces

(figure 5).

5. Sound Insulation Provided by the Facades Alone

The insulation values given by the two types of facade alone are presented for different values of the angle of incidence (9) of the

sound waves reaching the facade:

6 = Arc cos (cos <j> cos y)

Measurements were made with the angle 6 given the value zero and values

within the range 30°± 10°, 60° ± 10° and 80° ± 5°.

The values of the normalized sound insulation given by these facades

are not exactly the same for a given angle of incidence if the values of

the angles <j> and y are different. This appears to be attributable to diffraction of the sound waves at the edges of the door and window openings,

the effect of such diffraction being slightly different for the same angle

of incidence if the values of the angles <(> and y are not the same. Otherwise a center of symmetry would have to be assumed for each individual facade.

Examination of the results obtained (figures 6 and 7) shows that

there is little difference between the sound insulation obtained with 10 mm

glass and that with ordinary glazing using 2.9 mm thick. Indeed, in the

range of frequencies from 800 to 1600 Hz , that is the upper medium

frequencies, the normal glazing has a better sound insulation than the

10 mm thick glass. This is due to coincidence effects, the critical

frequencies for 10 mm glass and ordinary window glass being 1200 and 4000 Hz respectively, i.e. in the medium and high frequency ranges respectively.

On the other hand, at low frequencies, and at all frequencies for angles

of incidence less than 40°, the thick glass is a distinctly better

insulator than the window glass, which is in accordance with the mass law.

It will be seen that the shape of the curve of sound insulation

plotted against frequency varies according to the angle of incidence,

especially for the facade with sealed glazing, whereas the average

insulation changes but little with incidence. Nevertheless the thick

glass displays a slight minimum in the insulation curve at an angle of
about 60° and a maximum at an angle of incidence below 30°. Table I has

been drawn up to illustrate these facts. In this table values are given

of the average sound insulation for the low, medium and high-frequency

bands—' and the overall insulation calculated in dB(A) for the traffic

noise frequency distribution—/ . These values are given for each value

of the incidence, as defined by pairs of values of the angles <j> and y.

As for the effect of sealing the doors and windows, it can be seen

that the increase in insulation achieved by weatherstripping these

openings is slightly greater for high frequencies than for low, and

slightly greater for small angles of incidence than for great. It is of

the order of 2 to 6 dB, which is not negligible.

6. The Effect of Opening a Traditional Type of Window upon the Sound

Insulation that It Provides

Table I includes values (average and overall) of the sound insulation

of the traditional facade unit with the door closed and with the window

successively:

closed (with weatherstripping fitted)

closed (without weatherstripping)

partly open, the opening light being held by the stay,

- wide open.

As long as the angle of incidence of the sound waves does not exceed

70° or so, this angle has only a very slight influence upon the value of

the insulation provided by the traditional facade, whatever position the

opening light may be in.

Under these conditions, the traditional facade wall provides an overall sound insulation of:

4 to 6 dB(A) with the window wide open,

12 dB(A) with the window partly open,

22 dB(A) with the window closed but not weatherstripped

27 db(A) with the window closed and fitted with weatherstripping.

Thus, the sound insulation is very small when the window is open.

When the angle of incidence 8 assumes very high values, however,

the overall sound insulation values are a little higher, especially for

the cases when the window is open.

1/Cahier 554; Volume No. 66; C.S.T.B.; February 1964

i/cahier 599; Volume No. 71; C.S.T.B.; December 1964 (See figure 21)

6
For example, when 6 is greater than 80°, the overall insulation

is

:

8 to 12 dB(A) with the window wide open,

14 to 17 dB(A) with the window partly open,

25 dB(A) with the window closed but not weatherstripped,

29 dB(A) with the window closed and fitted with weatherstripping,

Under these conditions the sound insulation provided by the open window

is no longer negligible.

7. Sound Insulation Provided by Facade with Balconies and Loggias

(without Absorbent Materials)

The experimental work continued with measurements of the sound

insulation obtained when both the facades were fitted with open balconies,

closed balconies, and loggias (figure 5). The traditional facade was tested with its window wide open and its door closed, whereas the facade

incorporating sealed glazing was tested in the same condition as described

in Section 5 above.

The normalized sound insulation was measured for the various values

of the angles of elevation (4>) and azimuth (y) already given. The angle

of incidence 6 has little or no meaning when balconies are fitted.

Figures 8, 9 and 10 each show four graphs representing the normalized

sound insulation for angles of elevation <[> = , <j> = -30°, $> = -60°, and

<j> = -80° at angles of azimuth 0, 30°, 60° and 80° (except for <j> = -80°

when y takes the value only)

.

The balcony or the loggia contributes only a slight increase in the

insulation and then only if the angle of elevation is great enough:

at least 60° in the case of open balconies,

at least 30° in the case of closed balconies and loggias.

The insulation may even be slightly reduced for angles of evelation

less than those given above, because the balcony acts as a collector of

sound rather than as a protective screen. On the other hand, the insulation

is slightly improved for large angles of elevation and azimuth, due to the

fact that the balcony shades the glazing and, in addition, reflects the

diffracted waves at an incidence less than that of the direct waves. The

latter effect may either have practically no effect upon the insulation

(in the case of a window of traditional type) or may improve the insulation

(in the case of sealed glazing)
Table II gives the increase in overall sound insulation for a frequency distribution corresponding to that of traffic noise when a facade is fitted with a balcony or a loggia.

8. Facades with Balconies and Loggias with Sound -Absorbent Material

Applied to the Inner Surfaces

It was noted that the effect of balconies and loggias on the sound

insulation of the rooms was slight. This fact can be attributed to the

reflection of the sound waves incident upon the underside of the balcony

(or the loggia) of the story above, which tends to create an image of the

sound source in direct view of the shaded room. Consequently, attempts were made to eliminate this reflection by applying an effective sound

absorbent material to the inner surfaces of balconies and the undersides

of those on the upper story.

The improvement effected by this absorbent material becomes

distinctly greater as the angle of incidence is increased and is greater

for the loggia than for the closed balcony and, a fortiori, for the open

balcony (see figures 11, 12, 13, and Table III).

For an open balcony this improvement is always very small but it

becomes appreciable (approximately 5 dB(A) improvement) in the case of

the closed balcony for angles of elevation in excess of 30° (absolute

value) , and reaches about 10 dB(A) in the case of the loggia, also for

angles of elevation greater than 30°

9. Calculation of Sound Insulation for a Line Source Noise

Knowing the insulation values given by facades when the sound arrives

from a definite direction, one can deduce the insulation that would apply

when the source is not a point but a continuous straight line, as is the case of noise from a main road at an unobstructed site. All that is

required is to integrate the sound intensity emitted from each element of

the road and transmitted through the facade with the attenuation

corresponding to the angle of incidence.

Table IV gives values of the difference between the free-field sound

pressure level at the center of the facade and the reverberant sound

pressure level within the room, for the various types of facade investigated

and for various values of the angle <j> subtended by the center-point of

the facade at the point on the road nearest to the facade. It can be seen

that for angles of elevation <j> greater than 45° the insulation of the

facade, when fitted with an absorbent-lined loggia and with the window

wide open, is considerable, exceeding 15dB(A)
10. Conclusions

Surveys—' have shown that, for external noise from a main traffic

route, the average sound pressure level would be considered to be

acceptable if it did not exceed 63 dB(A) immediately outside the facade,

which corresponds to 60 dB(A) measured under free-field conditions (for

example, before the building is erected).

From the measurements reported above, it can be deduced that this

corresponds to sound pressure levels within the rooms of about 40 dB(A)

with the window closed and 55 dB(A) with the window open. This could be

regarded as an assessment of the requirements of the occupants.

The presence of a loggia lined with absorbent material and of

sufficient elevation (<j> > 45°) with respect to the road in front of a facade enables the free-field external noise level to rise to 70 dB(A)

before the above internal noise level criteria are exceeded.

If such favourable circumstances cannot be arranged, then, when the

external noise level exeeds 60 dB(A) , the rooms must be fitted with

mechanical ventilation and air-conditioning so that the windows can be

kept closed when the rooms are occupied.

In this case, the external free-field sound pressure level is

measured and the type of facade is selected on the basis of the data

given in the accompanying tables, so that the insulation the facade

provides will be sufficient to keep the internal sound level down to

40 dB(A)

.

I/cahier 762; Volume No. 88; C.S.T.B.; October 1967
Figure 1 Experimental Bui/ding for investigating the sound insulation of facade walls.

10
Angle of Azimuth Angle of Elevation Point Source of Noise

Figure 2. Geometrical definitions

Fi'9Ure 3. Sound sources used for the measurement of the sound

insulation of facades.

Table showing the sound sources used in the measurements

for the various frequency bands and elevations.

^^--•v^F re q ue nc y

E levation^^-^^^ 1 00 to 500 500 to 3150 -80° and -60° 4 LS Baffle Exponential horn LS

-30° and 0° 9 LS C olumn Exponential horn LS

Figure 4.

Microphone traversed using a turntable within the testroom (fitted with

traditional— type facade

wall.)

11
Figure 5 Facades

with open balcony (see—through)

with closed balcony (solid)

^ ^ ^

with open balcony and absorbent lining

with closed balcony and absorbent lining

with loggia with loggia and absorbent lining

12
Table 1 Bare Facades

frequencies, and overa

traffic— noise frequenc

in dS, for low (G), medium (M) and high (A) iulation ID), in dB|A). calculated for a tribution (cahier 559, Figure 21, d 3 mj

.

A

lnC,de ""

30 60 75 30 60 75 30 60 80 ^nn* - 30 - 30 - 30 - 30 - 60 - 60 - 60 - 60 - 80

angle, 6 30 60 75 30 40 64 80 60 64 75 85 80

G 30 30 33 32 30 29 30 30 30 29 30 31 30 Facade with M 34 32 31 32 32 31 30 32 29 27 29 29 28

10 mm thick A 42 36 40 42 37 34 37 41 37 37 43 46 44 D 32.5 [32 31 32 32.5 31 30 32 29 28 30 30 29

G 22 23 22 26 23 24 24 26 23 22 25 26 23

E Window and door M 30 29 29 30 26 26 27 31 29 29 28 32 30 weatherstripped , A 34 33 30 33 31 29 30 33 30 30 32 35 35 a

D 28 28 27 30 26 26 27 29 27 27 27 29 28

S

G 19 20 20 23 20 21 21 23 21 22 23 25 20 " Window and M 24 24 26 27 24 23 24 27 27 24 26 28 26

E door closed A 23 23 21 23 22 21 20 24 27 25 27 29 28

° 22 22 22 26 22 22 21 25 25 24 25 27 25

i G 11 12 11 15 12 14 15 17 13 11 14 16 11

•a Window M 14 14 13 17 12 11 14 18 14 13 14 17 16

(door closedl A 14 15 13 13 13 11 12 17 15 13 16 18 18

s D 12 13 12 15 12 11 13 17 13 12 14 17 14

5 G 8 9 8 11 9 10 10 12 10 8 10 13 8

h- Window open M 4 5 7 8 4 3 9 12 8 6 9 11 11 Idoor closed) A 3 4 6 7 4 4 8 12 7 7 10 12 13 D 4 4 6 8 4 4 8 12 7 7 , 9 11 10

Figure 6. No dB

60

SO

40

30

20

W

=

-- /

J

/ /

t

•—\ / \ J /

v s\ / \v s-/

_s S / / L. ^~-«,r*/ V O

T/

1 /r* ^v / NS

dB

60

50

40

30

20

10

e=3o°±id

v

t X

, ^ *-y V*

J SsN / s -. j/± — /--

-• fj / Vff / -^ / —\\l * ^

S \ ^\ f„ ? N/

6 30° for 5 =0(lp = -30°)

H H U i J - \J100 200 400 800 1600 3200 Hz 100 200 400 800 1600 3200Hz

13
Figure 6. (cont'd.)

1. Sealed glazing (10 mm thick). Volume of test—room: 34 mJ

2. Traditional window, weatherstripped (normal glazing).

Area of windows: 3.6 m^

NOTE: For clarity, the results from angles of incidence which give

insulation values that differ from one another by very little are grouped together (expressed as the average for 2 or 3 angles

of incidence.) dB

60

50

40

30

20

10

9=60*10

o

j

i ,

III

,

I s 'i

/

\ 7^

~i. kj- ^ ^ /

ti

' * /

/ "" \ f,n~

\ ^-. >^v

'

"S = 0,puis30°(f = -30°).

- Ju

dB

60

SO

40

30

20

10

0=60*10

O

!

V-"

,v «?

' tX/ ^

. V- / ' f« -

J yW 2 - \

•; V

3 60"forT=O( J =60"). 6 64°for-f=-30(!f =60°).

!: ) = Oet OU(T - 3U "J

100 200 400 800 1600 3200Hz 100 200 400 800 1600 3200 Hz

dB

60

50

40

50

20

10 _ 975o for^00f = 75)°) _ 9 80° for f =-30 U = 75°)

, (9 75° for -f =T = 60° — Average on 6 80 c

for!f = 0(tf=-80°)

(.9 85°for!f=80(f = -60°)

dB

60

50

40

30

20

10

o o 9=80*5

2

"

i ^/\

t ^*" ' A J* : "\"

i

,i* A

\

1 Average of 9 75"ef 9 80"

(for< = 75°,)Pbeing equal0°

then -30°: . 9 75° for -7 = 1 =60°.

Average of 9 80°et 9 85°

for =O0r = -8O°)etJ = 8O°

b .

100 200 400 800 1600 3200Hz 100 200 400 800 1600 3200Hz

14
Figure 7.

Increase in normalized sound insulation when normal glazing is replaced by 10 mm thick glazing (bard facade).

dB dl

+ 20

+ 10

- 10

e 60° for {

f )50 -— f ° r [* nul

/ /

//

{/ / // /

/• r\ \ / \ / V 1/

• —

100 200 400 800 1600 3200 Hz

dB

o 7R .„ an r ee

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758C

75

°

°

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for

for

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14 10 H

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64° f jr {t

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If =- 60 — for ]y = 30

f

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100 200 400 800 1600 3200Hz

dB

20

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I

80to85°

6 8 —9 8

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f = - 80

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\ \^V

\

100 200 400 800 1600 3200Hz 100 200 400 800 1600 3200Hz

15
Figure 8 Open Balcony

dB

60

SO

40

30

20

10

<f =

I

,'/' 7

,y

^ •

I .. / % /

"•4/,f*K -^VSf^

%ffl 7 |V. •V

4 -' \ >A Ns h

<it~

K* \

-V > —\ s V

> "v^ \ _\^:~

\

\ *P s- III ii s

100 200 400 800 1600 3200 Hz

dB

60

SO

40

30

20

10

Y=-60°

i

• '

/'/', ^,i

. I 1

; 'r

tl

/,'

, »

1 ? *^f

kg" '

„ -r

s.

t "hi

K. _ I.

\\ ^VJ

,\ -- \\

fv

y -. y - -j __ '' *" / --./ {_ /

y

1' L^ ^

, r* V

' — «i, — —

dB

60

50

40

30

20

10

— ^ = -30"

,

,'j r

// r;

< ' N

//' <" \. ^ //

,\ *5.

f iV^1 «*jw Z^&e •/ V-.--\

n V

—

-^h\ \ \ r / ^ „ —

> s

/ SL s ^ '!^. i^r

" v y v

i i ^2

100 200 400 800 1600 3200Hz

dB

60

50

40

30

20

10

| ! ^=-80° -Uf-

! i

• Y - ; / ! !/ ' / "\ y 1

' ' /*" \/l i / v

a

' /ty- M^ =f=

z+z

i ! -H-U «^3r

i"»« _•*

•^y' '\ / ! ^f =F -A/ f-

1

1 J

1

KM) 200 400 800 1600 3200 Hz 100 200 400 800 1600 3200Hz

1. 1 mm thick sealed glazing (3.6 m )

2. Traditional window, open (1 .8 m ) Volume of test—room: 34 m

Angles of Azimuth r = O Y = 30° y= 60° r = 8o°

16
Figure 9. Closed Balcony

dB

60

SO

40

30

20

10

f = o

4 J/ //

1 /•'

/ >

N* /-, A/ 7

\ „

' — v

t-3? ^yi 'iC- -' V 3?^-// \ / 3V;I ^

\f^r

.

*-As- ' '"? y>

—s >

r^ ^

u ~ -- ^

; ?

100 200 400 800 1600 3200Hz

41

60

50

40

30

20

10

f=-60° ,'

> /

i> J

• '/ >

:/

(,'t i\ \ ??, yt ^ y / \\ ^

,\ "-

t 3 » is v

tt

/ / >,

r r. ^ ^-~< — >

j» •^ ,* ^f Ai'

KM) 200 400 BOO 1600 3200Hz

1 . 10 mm thick sealed glazing (3.6 m )

2. Traditional window, open (1 .8 itt) Volume of test-room: 34 rrr

dB

60

50

40

30

20

10

?=-30° .

' J

f

/

/

I j /

\* N. \ */

ZLV

I \

, y

yf \ \

* • ^7^ ^ '"N *\- £ - i-"

100 200 400 1600 3200Hz

dB

60

50

40

30

20

10

cp- ftn° 1—

y

1 T- ou — /

X- O /-

fL_

v

= ~ J

___^_^-f Kls,A

,2

_^

7^Y~^ ^£7^7^"^^

A/- l

EEEE

100 200 400 800 1600 3200 Hz

Angles of Azimuth Y = "V = 30° Y= 60° Tf = 80°

17
Figure 10.

Normalized Sound insulation: Loggia

dB

60

50

40

30

20

10

?=0 ,.

/j / _J 1\ .* //

\ t'l / -.1

s. 1

<. ' ,/ \ -L'- -V

* -0 >*, J* „--

,

y -> s

, * V

\\[f >y*" \ y

UK/ \v

\7

.. V — i- \ /

\ x! \

k V —

\ ">

-* L - ^ "-

--^.=^2

KM 200 400 800 1600 3200Hz

dB

60

50

40

30

20 5

10

f=-60° /

1

/

/ i

//

i ,,

i /,i

/

\ it ^ \ \ ' t \; s f il \ * N • .^« j—

-V -^: v\ '

A , 2_ s^- \\^/"

??

,' 2

"» • s

\\ k / ^ i «. ^

ill ^

y

' \

h\ ss

*( —

dB

60

50

40

30

20

10

f=-30°

/ 1

I i

/

— •y -

„ X

\\ t

» \ s

\ , t ,— >' A-r-V . , \

l ^ *

I '••'

*^ I

I

S

N >s / \

- "T — *-.. y

_v "* • ^ ,. <•

i XtO 200 400 BOO 1600 3200Hz

dB

4 Ml

50

40

30

20

10

1 T=-80° y

/

Y=i O\J ~ty

s*

X /'

-iX- 7^ T-X -4

i V~x z

,s a 7^ ^' y

' \ / \ t. 3_ Z_ ^Z ~V

100 200 400 800 1600 3200Hz 100 200 400 800 1600 3200Hz

1. 10 mm thick sealed glazing (3.6 n/

2. Traditional window, open (1 .8 rrr) Volume of test-room: 34 m

3

Angles of Azimuth y = X = 30°

. "5"= 60° Tf = 80°

18
Figure 11. Normalized sound insulation: open balcony with

absorbent lining

dB dB

60 i

1 60

SO

40

30

20

10

f=0:

No measurements made,

it is assumed that the open

balcony curves would apply

in this case.

100 200 400 800 1600 3200 Hz

dB

60

50

40

30

20

10

^=-60° //

! /

/ / :l

i

: 1

• / # / ^1\ /

E>*\

y 1

fs <

..-

/ —

/

A

' -=• \ t f **

•/, \'\ / > v _ ^' -. ^' --- " v •* /s

1

50

40

30

20

10

?=-30°

/

•

r

rC

~2 //

k * /. •/ y

"

V >\/^•' — v.. V ^2 2

/ /

"

/

* ^ * a

s

s^

» •n." N ^P s

\ \

lC" -^ _> ,

100 200 400 800 1600 3200Hz

dB

60

50

40

30

20

10

1 1 1 1

| 1/|

1 Cf

; _— OUQf) ^t A

Z

Y - D _A \J 7

I f

±-^kX

7^ —^r

T

/

j, ' K *—^ 4-v

1

j \' c -^^. ^

/tT1 ^'_i ,

i r

7X-ZT5ZL

±t

100 200 400 800 1600 3200 Hz 100 200 400 800 1600 3200Hz

1 . 10 mm thick sealed glazing (3.6 m )

2. Traditional window, open (1.8 rrr) Volume of test-room: 34 m^

Angles of Azimuth Y=o Y = 30° r= 60° 6"

= 80°

19
Figure 12.

d|

60

SO

Normalized sound insulation: closed balcony

with absorbent lining dB

60

50

40

30

20

K)

? =

No measurements made,

it is assumed that the closed balcony curves would apply in this case.

_ 100 200 400 800 1600 3200Hz

dB

60

50

40

30

20

10

¥'

T-60 //

Tst

A aY

4 is

r / ' f

'/ s - V

* Ts

,*'

'*

.' &

^ .fr^

••, . -yt-T-

.', L". /

' ? / \\

< -1 j, / s Y Jfc- ^ «->* ^ J

i

?2

40

30

20

10

<f=-30° /

' /

/ 1 :' f r

„.- TM^ v«; >,ff V k - <£r ..*','\

.- * — - .-' ' "**

-~,

-. \

•

\

, __—_. — • —

»

r-

\ _J I -* "^ •

\_ /

i ^Np" /N.

* > ,' *! k- ^ \

"~"

i

i | KM) 200 400 800 1600 3200Hz

dB i 60

50

40

30

20

10

100 200 400 800 1600 3200 Hz 100 200 400 800 1600 3200Hz

1 . 1 mm thick sealed glazing (3.6 rrr) n

2. Traditional window, open (1.8 m ) Volume of test— room: 34 m m3

.

Angles of Azimuth Y = Y r 30° Y = 60 c Y = 80°

20
Figure 13. Normalized Sound insulation: Loggia with absorbent lining.

dB

60

50

40

30

20

10

dB

| <f =0 /

/

/ -4- I

y\

*

•" /

^

' / /

/ fi

, *. y" \ /

y / \

/ 1/ I ?\\ / <' \ \ i * ;V I /

<S --u \"

V.TV

vIV

- ^^* , ...

,1 -- ' --

*"

t " y ,- V ., -.—

-' ._ /

-^>-<\'^ k /

dB

60

SO

40

30

20

10

KM 200 400 800 1600 3200 Hz

1 iji'yt

?=-60°

i

. ^22 /A

| ,'

/ 7

1L/ ^X£ /

/ Nx

/ ^'

-,-*

-* ,' *

-,1 .^ r_

* &£

-£i__ •/ - —

k*1-

*>. •

/ ^

'*% '/ ^

4 T

u r^

i^ ^- 15 .•

_=*. ^^- '*

|

|

DU ?=-30°. / /

/ /

1 / 50 _ — \si A >

.,. ' / \

,,' A'-

,_,_ / s\

40 T~ \ / / s\ \ s^ (** , s

\\ y—r- .. V _ -* ""« ' 30 rftm -* y

_**

-

' 20 '

~~

- — "Y

N T

\n lkN. _ *<» — — — —

10 N _

_S

dB

60

^2

3200Hz

1

50

40

30

20

10

/

T —80 / v « ~L- o=0 ,^JtL

/

/

^. /

\ ^*

//

/"^IS

****» / /\ / _JL\ z_ A /

100 200 400 800 1600 3200 Hz 100 200 400 800 1600 3200Hz

1. 1 mm thick sealed glazing (3.6 m)

9

2. Traditional window, open (1.8 m ) Volume of test—room: 34 m

Angles of Azimuth Y = O t = 30° r= 60° r = 8o°

21
Table II Increase in the sound insulation of a room from

external noise when the facade is fitted with a balcony or loggia having sound absorbent material applied to its internal surfaces.

The values given below represent the average

increases in insulation for low (G), medium

(M) and high (A) frequency bands and the increases

in overall insulation, in dB(A), (indicate by

the letter D) for the frequency distribution corresponding to traffic noise.

Azimuth r 0° 30° 60° 75° 0° 30° 60° 75° 0° 30° 60° 80° 0°

E le vation 9

0° 0° 0° 0° - 30° - 30° — 30° - 30° - 60° - 60° - 60° - 60° - 80°

Traditional G - 3 - 2 - 2 - 3 - 3 - 2 - 1 - 2 - 1 - 1 - 2 + 4 Window M - 1 - 1 - 1 + + 2 - 1 + 1 + 1 + 2 + 3 + 5 Open A + 1 - 1 - 1 - 1 - 1 - 1 4- 2 + 4 + 5 + 7

Open

Ba Icony

D - 1 - 1 - 1 - 1 + 1 - 1 + 1 + 0.5 + 2 + 3 + 5

Facade G - 2 - 2 - 3 - 2 - 2 + 1 + 3 + 3 + 2 - 1 4- 2 w ith M - 1.5 - 2 - 2 - 1 + 1 - 2 + 1 + 5 + 5 + 7 + 11 sea led A - 1.5 - 1 - 1 - 1 - 1 + 3 4- 2 + 2 + 4 + 3 + 3 + 7 glazing D - 1.5 - 1.5 - 1,5 - 1 - 1 + 1 - 1 + 2 + 4 + 4 + 5 + 9

Trad it iona 1 G - 1 - 1 - 2 - 2 - 1 - 1 - 1 + 2 + 1 + 6 Wind ow M - 1 - 2 - 2 + 2 + 3 + 2 + 3 + 3 + 4 + 7 open A + 1 - 2 - 2 + 1 + 2 - 1 + 1 + 3 + 4 + 5 + 6 4- 9

C losed D - 1 - 2 - 2 + 2 - 2 + 3 4- 3 + 3 + 4 + 7

Balcony: Facade G - 3 - 3 - 2 - 2 + 1 + 1 + 2 + 2 + 3 + 2 + 5 with M - 1 - 2 - 2 - 1 + 1 + 1 + 1 + 1 + 3 + 6 + 6 + 7 + 10 sea led A - 1 + 1 - 1 - 2 + 2 + 5 + 4 + 5 + 7 + 3 + 2 + 7 glazing D - 1 - 1.5 - 1.5 - 1 + 1 + 2 + 1 + 3.5 + 6 + 5 + 5.5 + 9

Traditiona 1 G - 1 r 1 + 2 + 2 - 1 + 2 + 4 4- 2 + 5 -r 4 + 2 + 8 Window M + 1 - 1 + 1 + 6 + 1 + 3 + 3 + 3 4- 3 + 6 + 6 open A - 1 - 1 + 2 + 8 + 1 + 1 + 5 + 2 + 6 + 7 + 11 4- 8

Loggia: s

D - 0,5 + 1.5 + 6 + 0.5 + 2 + 1 + 3.5 + 1.5 4- 4 + 4 + 6 + 7

Facade G - 1 + 3 + 2 + 3 + 3 + 2 + 5 + 5 + 1 + 7 with M + 5 - 1 + 2 + 4 + 3 + 5 4- 6 4- 10 + 14

sea led A + 1 + 4 - 2 + 4 - 3 + 2 + 4 + 4 + 6 + 4 + 7 + 15

1

\ glazing D - 0.5 - 0,5 + 5 - 1.5 + 2 + 3.5 + 3 + 5 r 6 + 8 + 12

22
Table III

Increase in the sound insulation of a room from

external noise due to the presence of a balcony

or a loggia (without sound—absorbent linings).

The values given below represent the average

increase in insulation for low (G), medium (M) and high (A) frequency bands and the increases

in overall insulation, i n dB(A) (indicated by the

letter D) for the frequency distribution cor- responding to traffic noise.

Incidence Azimuth Y

0° 30° 60° 75= 0° 30 ° 60° 75" 0° 30° 60° 80° 0»

E levation cp — 30' — 30° - 30° - 30° — 601 - 603 - 60' - 60s — 80°

1 Traditional G — 1 + 3 + 2 + 2 + 2 + 1 + 6 w tndow M + 2 + 1 + 6 + 2 + 6 + 6 + 8 + 9 Open

Ba Icony with

open A

D

+ 1 + 1 + 1+ 7 + 5

+ 3 + 2+ 6 + 5+ 7 + 6

+ 8 + 7+ 12 + 10

absorbent Facade G — 1 + 1 + 1 + 3 + 4 + 3 + 3

lining:

J with M + 1 + 2 + 2 + 1 + 7 + 10 + 8 + 10 + 15 sealed A + 2 + 2 + 3 + 3 + 6 + 8 + 8 + 8 + 11

glaz ing D + 1 + 2 + 2 + 1 + 6 + 9 + 8 + 7 + 11

f Traditional G + 2 + 2 + 6 + 8 + 3 + 5 + 4 + 3 + 10 w indow M + 4 + 6 + 6 + 9 + 7 + 8 + 9 + 11 + 11 C losed 1 open A + 2 + 5 + 9 + 12 + 15 + 15 + 13 + 14 + 16 balcony' with D + 3 + 5 + 6 + 9 + 7 + 7 + 8 + 9 + 11

sound —

absorbent! Facade G + 3 + 5 + 2 + 2 + 4 + 5 + 4 + 2 + 6

lining: 1 with M + 4 + 6 + 7 + 6 + 11 + 13 + 11 + 12 + 14

f sea led A + 1 + 5 + 10 + 9 4- 16 + 17 + 13 + 12 + 13

1 glazing D + 3 + 5 + 6 + 5 + 10 + 11 + 9 + 9 + 12

! Tradit iona 1 G + 3 + 3 + 6 + 7 + 3 + 4 + 7 + 8 + 6 + 8 + 8 + 7 + 12 window M + 2 + 1 + 7 + 15 + 5 + 8 + 11 + 16 + 9 + 11 + 13 + 16 + 14

1 open A + 2 - 2 + 6 + 20 + 2 + 3 + 15 + 21 + 16 + 17 + 17 + 22 + 17

Loggia D + 2 + 1 + 7 + 12 + 4 + 5 + 11 + 14 + 9 + 11 + 13 + 15 + 14

sound— J Facade G + 1 + 5 + 2 + 5 + 5 + 6 + 7 -1- 5 + 6 + 8 + 6 + 5 + 10 absorbentl

lining 1 with

sea led

M

A

+ 4 + 3+ 5 + 7+ 6 + 2

+ 13 + 11

+ 5 + 2

+ 10 + 16+ 12 + 13+ 13 + 13

+ 12 + 17

+ 15 + 17+ 15 + 13

+ 18 + 14

+ 17 + 16

g la z i ng D + 4 + 5 + 5 + 12 + 5 + 10 + 12 + 12 + 12 + 14 + 13 + 14 + 15

23
Table IV Sound insulation A, in dB (A), defined as the difference

between the sound pressure level that would apply at the centre of the

fagade under free-field conditions and the reverberant sound pressure

level within the room immediately behind the facade (volume 3U m , reverberation time 0.5 second), when the noise source is a main road,

unobstructed and parallel to the facade. (i|> is the angle of elevation

of the centre-point of the facade measured from the point on the road

nearest to the fagade.)

Arrangement of Facade Value of <i<

Openings

Balcony or loggia Absorbent

lining (Abs)

15° 30° 45° 60° 75-

None 6 6 7 8 10

Open Window

(1 .8 m2

)

Open ba Icony Abs

5

5

5

6

7

8

8

11

12

16

C losed ba lcon\ Abs

5

5

6

8

8

12

9

13

12

19

Loggia Abs

7

8

8

11

9

15

1120

523

N one

Abs

31 31 31 30 30

1 mm

sealed glass

pen ba Icony 30

31

3132

313332

33

33

34

(3.6 m2

) C losed balcony Abs

30

32

32

34

32

35

33

36

34

36

Loggia Abs

33

38

324032

41

3442

3643

24
FORM NBS-114A (1-71) U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS TN-710-22. Gov't Accession No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE An Investigation of the Protection of Dwellings from External

Noise through Facade Walls

5. Publication Date March 1972

6. Performing Organization Code

7. AUTHOR(S)

P. Gilbert

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. Project/Task/Work Unit No. NATIONAL BUREAU OF STANDARDS DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Same as No. 9.

13. Type of Report & Period Covered Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant bibliography or literature survey, mention it here.) This paper is translated from the French original and is published under the Building

Research Division/Centre Scientifique et Technique du Bat iment information exchange program.

&n investigation was conducted to determine to what extent the installation of balconies

and loggias at various angles of elevation from a noise source could improve the sound

insulation of a facade wall. Measurements of the sound pressure level were first carried

out on two types of facade, one incorporating traditional window joinery and the other

incorporating sealed glazing. Following this, the sound insulation provided by facades

fitted with open and closed balconies and loggias (with and without sound absorbent

materials applied) was determined and compared with the previous measurements. It was

found that for angles of elevation greater than 30°, both the closed balcony and the

loggia fitted with absorbent materials appreciably improve the sound insulation, whereas

the open balcony does not.

17. KEY WORDS (Alphabetical order, separated by semicolons) Facade; noise ; sound insulation; Sound

pressure level; walls.

18. AVAILABILITY STATEMENT

H UNLIMITED.

I I FOR OFFICIAL DISTRIBUTION. DO NOT RELEASE

TO NTIS.

19. SECURITY CLASS

(THIS REPORT)

UNCLASSIFIED

20. SECURITY CLASS

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26

22. Price

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