Assessment of acoustical performance of green rated office buildings in Dhaka city

Abstract

According to recent investigations, indoor acoustical performance of green rated office buildings has been found to be unsatisfactory. This contradicts with green building rating criteria, where a good Indoor Environmental Quality (IEQ) is crucial for the well-being of occupants. Insufficient attempts have been taken to enrich the acoustical environment of these buildings. The situation in Bangladesh is unestablished, with no study undertaken to determine the existing acoustical performance of green rated office buildings. Specific acoustical considerations for performance should be met in green rated office buildings to conserve the environment and natural resources, and also provide a comfortable acoustical environment for its occupants. The aim of the thesis is to explore this issue in depth, by assessing the current quantitative and qualitative deviations in acoustical performance of green rated office buildings in Dhaka. Primary data was collected through physical site survey to obtain quantitative data in selected office buildings, and through qualitative questionnaire survey of occupants. Secondary data was collected by analysing previous studies of similar topics through journals and other written records. Open, semi-private and private types of office spaces were studied in this research. Results from both quantitative and qualitative surveys confirmed to similar sets of findings in background noise levels, reverberation time, speech intelligibility and speech privacy in all the office spaces. Overall acoustical performance in terms of these parameters was found below the level of required standard. Lack of awareness on appropriate acoustical measures for office buildings existed among design teams, contractors and clients. High levels of background noise and poor speech intelligibility conditions were dominant, with most participants expressing dissatisfaction with existing background noise control measures. This affected well-being and work productivity of most employees. Deviations from acoustical performance standards were the highest in semi-private office spaces, where participants were also affected by unsatisfactory speech privacy levels. Conversely, open and private office users were less affected by existing acoustical performance deviations, suggesting the need for revised standards of acoustical performance for these spaces. In general, deviations in acoustical performance were not affected by the office’s vertical location in the building nor specific working hours, rather were dependent on proper acoustical design measures and planning guidelines. It is expected that the study findings may increase awareness on acoustical issues of green rated office buildings among associated design and client groups, and encourage necessary design measures in future green rated office buildings. Keywords: Green rated building, acoustical performance, office, Dhaka