Natural ventilation is often the only means of providing fresh air in domestic buildings and it may become the preferred method for other buildings as well, in order to conserve energy. The simplest way of achieving natural ventilation is to open a window or door, but the sound attenuation of the building envelope may be severely reduced. The effect of an opening on facade attenuation may be predicted, if the sound transmission loss values of the facade elements are known. The accuracy of such predictions has been investigated by measuring the traffic noise attenuation of the facades of an experimental building. Various percentages of open window area were examined, and the effect of staggering the opening sashes in a spaced double window was measured. [Work supported by A.R.G.C. and S.P.C.C.]
Historical data on road traffic noise was compared with fresh measurements made in 1984 and 1985 to assess the effectiveness of new and in-service vehicle noise limits. Trucks and buses have shown either no reduction or an increase of about one decibel, whilst cars and derivatives have mean maximum levels about one-third of a decibel lower. However, this small achievement is offset by the increased number of panel vans and forward control passenger vehicles on the road, which have mean maximum levels from 3 to 4 db(a) higher than the station wagons they are replacing. A decade of motor vehicle noise legislation has failed to have any noticeable effect on traffic noise levels for several reasons. Firstly, it has always been recognised that the adr levels are too high to affect all but the very noisiest of vehicles in each category. Secondly, the wide- open-throttle acceleration test has serious limitations as an indicator of vehicle noise emission in typical traffic conditions. Thirdly, adr tests are only applied to representative vehicle models. Finally, the in-service regulations in New South Wales are only applied in practice when a particularly noisy vehicle happens to be detected by one of a handful of inspectors. It is obvious that additional methods of reducing the traffic noise problem must be employed. The number of the covering record for the conference is IRRD 283994. (TRRL)
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