Sound measurements and natural ventilation in schools

Natural ventilation using open windows is an energy efficient and effective method of providing a good indoor air climate in schools. However, open windows not only let fresh air into the building but also external noise. The availability of automatically controlled windows enables precise control over the window opening distance in comparison with manually operable windows. This paper considers the benefits of using small opening distances to provide sufficient ventilation for a good indoor climate as well as attenuation of external noise. Airborne sound insulation tests on a window with different opening distances show that the sound insulation varies significantly depending upon the opening distance; the smaller the opening distance, the higher the sound insulation. In many cases, an opening distance as small as 1 to 2 cm can not only provide sufficient ventilation for a good indoor climate, but also adequate sound insulation. The results of sound attenuation tests, performed at BRE in the United Kingdom, are presented in this paper. In addition, empirical results from 3 different naturally ventilated schools, including two in Denmark and one in the UK are described. These results indicate that often only small opening distances are required to obtain a comfortable thermal and atmospheric indoor climate based on measurements during the year.