The Norwegian Facade Insulation Study: The efficacy of facade insulation in reducing noise annoyance due to road traffic

The efficacy of facade insulation in providing an improved indoor noise environment and in reducing indoor noise annoyance was examined in a socio-acoustic before-and-after study with a control group. An average equivalent noise reduction inside the dwellings of 7 dB was obtained from the facade insulation. Whereas 42% of the respondents were highly annoyed in the before-situation, this dropped to 16% in the after study. The conclusion is therefore that the facade insulation provided a substantial improvement in the indoor noise environment. The advantage with respect to indoor noise annoyance, of having the bedroom facing the least noise-exposed side of the dwelling corresponded to a 6 dB noise reduction. The changes in annoyance from noise reduction due to the facade insulation were in accordance with what would be expected from the exposure-response curves obtained in the before-situation. A total of 637 respondents participated in the before-study. Of these, 415 also participated in the after study. Indoor and outdoor noise exposure calculations for each of the dwellings were undertaken before and after the facade insulation was implemented. (C) 2011 Acoustical Society of America