The study of mosque acoustics, with regard to acoustical characteristics, sound quality for speech intelligibility, and other applicable acoustic criteria, has been largely neglected. In this study a background as to why mosques are designed as they are and how mosque design is influenced by worship considerations is given. In the study the acoustical characteristics of typically constructed contemporary mosques in Saudi Arabia have been investigated, employing a well-known impulse response. Extensive field measurements were taken in 21 representative mosques of different sizes and architectural features in order to characterize their acoustical quality and to identify the impact of air conditioning, ceiling fans, and sound reinforcement systems on their acoustics. Objective room-acoustic indicators such as reverberation time (RT) and clarity (C50) were measured. Background noise (BN) was assessed with and without the operation of air conditioning and fans. The speech transmission index (STI) was also evaluated with and without the operation of existing sound reinforcement systems. The existence of acoustical deficiencies was confirmed and quantified. The study, in addition to describing mosque acoustics, compares design goals to results obtained in practice and suggests acoustical target values for mosque design. The results show that acoustical quality in the investigated mosques deviates from optimum conditions when unoccupied, but is much better in the occupied condition.
In harsh climates, utilizing thermal insulation in the building envelope can substantially reduce the building thermal load and consequently its energy consumption. The performance of the thermal insulation material is mainly determined by its thermal conductivity (k), which is dependent on the material’s density, porosity, moisture content, and mean temperature difference. In practice, the k-value is normally evaluated at 24 C (i.e., k24) according to relevant ASTM standards. However, when placed in the building envelope, thermal insulation materials can be exposed to significant ambient temperature and humidity variations depending on the prevailing climatic conditions. The objective of this study is to assess and compare the effect of operating temperatures on the k-value of various insulation materials commonly used in the building envelope. The k-values for seven categories of insulation materials (i.e., fiberglass, wood wool, mineral wool, rock wool, polyethylene, polyurethane, and polystyrene) are measured at different mean temperatures using an automated heat flow meter. Some preliminary measurements are reported for the purpose of assessing the impact of k-value variation on envelope-induced cooling loads (Budaiwi et al. 2002). In this study, comprehensive measurements, comparison, and analyses of results are presented and discussed. These underline the k-value degree of sensitivity ((Δk/ΔC)/k24) of various insulation materials with rising operating temperature. This would allow designers to better evaluate the thermal performance of building envelopes leading to a more realistic thermal assessment and energy requirements of buildings.
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