Noise; final report : Presented to the Parliament ... July 1963.
- Great Britain. Committee on the Problem of Noise
- Date:
- [1963]
Licence: Public Domain Mark
Credit: Noise; final report : Presented to the Parliament ... July 1963. Source: Wellcome Collection.
48/256 page 34
![NOISE FROM OUTDOORS 122. The insulation of the building facade against external noise has not hitherto been regarded as of first importance, except for special buildings such as concert halls. The reason is that insulation against external noise is deter- mined largely by the windows [figures to illustrate this are given in the British Standard Code of Practice for Buildings (ref. 2)], and for practical purposes it may be assumed that a facade with a traditional area of windows in it will not give an insulation of more than about 20 dB and may give less if openable windows are ill-fitting. With the windows open even a little, the insulation will not be more than 10 dB. 123. From the table of ambient noise levels given in the previous chapter and from the desirable maximum interior levels suggested in paragraphs 117 and 118 of this chapter, it can be seen that this degree of insulation is insuffi- cient to prevent disturbance in rooms facing on to streets with busy traffic and bus routes, or near airports and other noisy places. On the other hand the levels in buildings exposed to noise intensities such as those of Group B* could be made acceptable if the insulation of walls with closed single windows could be increased to 25 dB, although, to be acceptable against the peak noise levels, an increase to, say, 30 dB would be better. Insulation of this order would be expected to give a very considerable improvement even in Group A*. We have been told that improvements in the design of windows to give better protection against wind and rain in the upper floors of high buildings are being sought. Success in this may be expected also to give some increase in sound insulation, though possibly it will not attain 30 dB. We feel that if, by additional effort in development, 30 dB could be reached in a facade with single glazed windows it would be of great benefit. (Wherever closed windows are used for sound insulation it is necessary to consider other forms of ventilation. There is, of course, no reason why the window should necessarily remain the source of ventilation : other means might well serve better.) 124. The maximum practicable window insulation is about 40 dB. To achieve this it is necessary to have sealed or very close fitting openable double windows with a space of 8 inches or more between the leaves, and with the reveals lined with a sound absorbent. Such windows, combined with reason- ably heavy walling, are probably adequate for the noisiest traffic or industrial conditions likely to be encountered, but this method of insulation requires a system of mechanical ventilation or of complete air-conditioning. It has recently been estimated (ref. 3) that these methods may add 20s. to 30s. per square foot of floor area to the cost of the building, and they have been gener- ally regarded as impracticable in, say, local authority flats. They have, how- ever, been used in some offices, hotels and hospitals in particularly noisy situa- tions. In Chapter VIII (Aircraft Noise) we refer to trials made for us on a system of openable double windows combined with a fan ventilating the room through a noise-attenuating appliance. The system is expensive at present, but we hope that future development may increase the possibilities of its wider use, for it could help to solve many difficulties. * See Chapter IV, Table ITI.](https://iiif.wellcomecollection.org/image/b32177756_0048.jp2/full/800%2C/0/default.jpg)
