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Noise inside buildings due to external air flows
Noise Inside Buildings due to External Air Flows
The noise inside high-rise buildings due to external and internal airflows (other than air-conditioning and compressed air supplies) is to be studied, under a Science Research Council grant, at the Institute of Sound and Vibration Research, University of Southampton. This work forms part of a study of the internal environment of buildings due to meteorological factors such as wind and temperature, other studies being of ventilation, heating, lift and door operations and smoke movement. Environmental problems due to wind and stack effects have been known for some time, e.g. in a discussion on a paper by Tamura,1 Barrett observed that, 'Considering environmental factors, air movement due to stack effect in tall buildings is accompanied by drafts and noise and difficulty is encountered in the operation of doors (leaf and elevator) due to pressure differences.' To the present writer's knowledge, however, there has only been one published paper on the noise aspect. Sealey 2 based his paper on work by Avery and Roberts, 3 who found the main aerodynamic noise source in high-rise buildings was from wind- and stack-induced flow through door cracks and into lift shafts and rubbish chutes. The maximum sound level recorded was 75 dB(A) in a wind of 55 km/h. It is the general aim of the project under discussion to provide quantitative data on the noise inside buildings due to meteorological factors, to identify noise sources, and to make proposals for controlling the noise produced in this way. A social survey to determine the annoyance caused by such 'natural' sounds would be very useful, but, until the time such a survey is carried out, NC ratings will be used to assess the annoyance produced. "The sources of noise can be grouped under three broad headings: (i) Noise from airflow over the outside of the building. Within this group are such sources as vibration of cladding, sunshades and other architectural features, separated flows, and aerodynamically excited cavity resonances. (ii) Noise from airflow into the building; noise from flow through doors, windows, ventilators, cracks, keyholes, etc. (iii) Noise from airflow within the building due to both wind and stack effects. Of the noises included in this group, the flow into lift shafts and rubbish chutes seems to be the most serious. Eventually it is hoped that internal and external flows and, hence, noise, can be related to building type, construction, size, permeability and surroundings, as well as wind speed, direction and temperature. So far only pilot measurements have been made to determine the seriousness of the problem and to assess the best way to gather data. An example of these measurements is given in Fig. I. An NC rating of 55 was obtained 10 ft from an open window situated in the separated 233 Applied Acoustics (5) (1972)---O Applied Science Publishers Ltd, England--Printed in Great Britain
234
F. R. FP.ICKE Windward side 70 I" i L J ~.
Lee '~K:le
& 0
Window closed 1cm. gap
rl
Wide open
•
-
Window i n ' h o w l i n g ' - position
"\
\\
\.
4o -
"-..
•o
,~
~ . ~
Wind spe(;rd ,~= 20 Knots
\
30-
\ \ \
2c 31.5
Fig. I.
.
t 63
1
I
125 2 50 O c t a v e band c e n t r e
t
t
t
500 1000 f r e q u e n c y (Hz)
2000
dBA
External flow noise spectra, measured I0 ft from it window in the eighth floor of a tenstorey office block.
60
L
o
8 co 1o > 30 - -
o
2o 31.5
O O
Windspeed -'~ 5 k n o t s Wind s~c:~ed -'~ 15knot$
t
t
t
63
125
250
I ~
I
t
1000
2000
O c t a v e band c e n t r e f r e q u e n c y
Fig. 2.
dBA
(Hz)
Variation o f spectra with wind speed in a twenty-four storey apartment block. Measurements were made in the fifteenth floor lift alcove.
NOISE INSIDE BUILDINGS DUE TO EXTERNAL AIR FLOWS
235
flow at the corner of a ten-storey office block. The levels, which, in this case, were subjectively estimated mean values, varied by quite large amounts and so in future it is planned to present them as percentile values. Variation of spectra with wind speed is given in Fig. 2 for a twenty-four storey apartment block. Measurements, in this case, were made on the fifteenth floor lift alcove and may be subject to variation in background noise level since they were made on different days at different times of the day. This Note was written for three reasons: (i) To provide information about this Science Research Council project at the Institute of Sound and Vibration Research. (ii) To seek information about people's tolerance of such noise. (iii) To find incidences where high sound levels occur due to this source. I should be very grateful if anyone who wishes to comment or advise on any of the above three points would direct their enquiries to me or Dr P. O. A. L. Davies at the Institute.
REFERENCES 1. G. T. TA.~UR.~, Computer analys;s of smoke movement in tall buildings, A S H R A E Trans., 75, pt. II (1969) pp. 81-92. 2. A. SE^LEY, Wind noise in tall buildings, Architects" Journal (1968) pp. 1151-3. 3. P. AVER~" and R. ROBERTS, Aerodynamic noise as a building nuisance, Birmingham School of Architecture (unpublished), 1965.
F. R. FRICKE,
Department of Building Science, The Unirersity of SheffieM, Sheffield SI0 2TN, (Great Britain) (Received: 29 July, 1971)
The noise inside high-rise buildings due to external and internal airflows (other than air-conditioning and compressed air supplies) is to be studied, under a Science Research Council grant, at the Institute of Sound and Vibration Research, University of Southampton. This work forms part of a study of the internal environment of buildings due to meteorological factors such as wind and temperature, other studies being of ventilation, heating, lift and door operations and smoke movement. Environmental problems due to wind and stack effects have been known for some time, e.g. in a discussion on a paper by Tamura,1 Barrett observed that, 'Considering environmental factors, air movement due to stack effect in tall buildings is accompanied by drafts and noise and difficulty is encountered in the operation of doors (leaf and elevator) due to pressure differences.' To the present writer's knowledge, however, there has only been one published paper on the noise aspect. Sealey 2 based his paper on work by Avery and Roberts, 3 who found the main aerodynamic noise source in high-rise buildings was from wind- and stack-induced flow through door cracks and into lift shafts and rubbish chutes. The maximum sound level recorded was 75 dB(A) in a wind of 55 km/h. It is the general aim of the project under discussion to provide quantitative data on the noise inside buildings due to meteorological factors, to identify noise sources, and to make proposals for controlling the noise produced in this way. A social survey to determine the annoyance caused by such 'natural' sounds would be very useful, but, until the time such a survey is carried out, NC ratings will be used to assess the annoyance produced. "The sources of noise can be grouped under three broad headings: (i) Noise from airflow over the outside of the building. Within this group are such sources as vibration of cladding, sunshades and other architectural features, separated flows, and aerodynamically excited cavity resonances. (ii) Noise from airflow into the building; noise from flow through doors, windows, ventilators, cracks, keyholes, etc. (iii) Noise from airflow within the building due to both wind and stack effects. Of the noises included in this group, the flow into lift shafts and rubbish chutes seems to be the most serious. Eventually it is hoped that internal and external flows and, hence, noise, can be related to building type, construction, size, permeability and surroundings, as well as wind speed, direction and temperature. So far only pilot measurements have been made to determine the seriousness of the problem and to assess the best way to gather data. An example of these measurements is given in Fig. I. An NC rating of 55 was obtained 10 ft from an open window situated in the separated 233 Applied Acoustics (5) (1972)---O Applied Science Publishers Ltd, England--Printed in Great Britain
234
F. R. FP.ICKE Windward side 70 I" i L J ~.
Lee '~K:le
& 0
Window closed 1cm. gap
rl
Wide open
•
-
Window i n ' h o w l i n g ' - position
"\
\\
\.
4o -
"-..
•o
,~
~ . ~
Wind spe(;rd ,~= 20 Knots
\
30-
\ \ \
2c 31.5
Fig. I.
.
t 63
1
I
125 2 50 O c t a v e band c e n t r e
t
t
t
500 1000 f r e q u e n c y (Hz)
2000
dBA
External flow noise spectra, measured I0 ft from it window in the eighth floor of a tenstorey office block.
60
L
o
8 co 1o > 30 - -
o
2o 31.5
O O
Windspeed -'~ 5 k n o t s Wind s~c:~ed -'~ 15knot$
t
t
t
63
125
250
I ~
I
t
1000
2000
O c t a v e band c e n t r e f r e q u e n c y
Fig. 2.
dBA
(Hz)
Variation o f spectra with wind speed in a twenty-four storey apartment block. Measurements were made in the fifteenth floor lift alcove.
NOISE INSIDE BUILDINGS DUE TO EXTERNAL AIR FLOWS
235
flow at the corner of a ten-storey office block. The levels, which, in this case, were subjectively estimated mean values, varied by quite large amounts and so in future it is planned to present them as percentile values. Variation of spectra with wind speed is given in Fig. 2 for a twenty-four storey apartment block. Measurements, in this case, were made on the fifteenth floor lift alcove and may be subject to variation in background noise level since they were made on different days at different times of the day. This Note was written for three reasons: (i) To provide information about this Science Research Council project at the Institute of Sound and Vibration Research. (ii) To seek information about people's tolerance of such noise. (iii) To find incidences where high sound levels occur due to this source. I should be very grateful if anyone who wishes to comment or advise on any of the above three points would direct their enquiries to me or Dr P. O. A. L. Davies at the Institute.
REFERENCES 1. G. T. TA.~UR.~, Computer analys;s of smoke movement in tall buildings, A S H R A E Trans., 75, pt. II (1969) pp. 81-92. 2. A. SE^LEY, Wind noise in tall buildings, Architects" Journal (1968) pp. 1151-3. 3. P. AVER~" and R. ROBERTS, Aerodynamic noise as a building nuisance, Birmingham School of Architecture (unpublished), 1965.
F. R. FRICKE,
Department of Building Science, The Unirersity of SheffieM, Sheffield SI0 2TN, (Great Britain) (Received: 29 July, 1971)