AN ASSESSMENT OF THE ACOUSTIC PERFORMANCE OF OPEN WINDOWS, IN LINE WITH VENTILATION REQUIREMENTS FOR NATURAL VENTILATION

摘要

As we all move towards a more sustainable future, the use of natural ventilation becomes increasingly important. In addition, our expectations and demands from buildings are increased. Naturally ventilated buildings are therefore becoming more frequently used within inner city locations and on other noisy sites, although our expectation of these buildings is not compromised, meaning that low internal background noise levels are still required. As a result, a better understanding of key factors affecting the acoustic performance of vented facades is required. The acoustic performance of a partially/minimally open window to a bedroom is stated to be between 10-15 dB. This figure is published in numerous documents hence this guidance is often used to assess the acoustic performance of vented facades to classrooms, healthcare, offices and other buildings. 10-15 dB for a partially open window is a very vague design guide and questions often arise as to whether this guidance can be used for natural ventilation, due to the large free area requirements for natural ventilation. This paper therefore looks at current literature on the subject of open windows. As well as publishing the results of onsite testing for a Velfac window, results are published for different window open areas and different opening combinations. The paper concludes with a comparison between free field measurements and laboratory diffused field measurements for similar window types. Along with a comparison of lab and field measurements, sound insulation levels for a range of vertical and horizontal angles are presented. In summary, this paper provides a useful insight into the acoustic performance of openable windows used in combination with natural ventilation.