Investigation of thermal comfort in bedrooms in Qatar

Abstract

Good quality sleep is essential for overall health and productivity of human beings. In a field survey in bedrooms in Qatar, 833 sets of occupant responses on thermal comfort and sleep quality before going to bed and after getting up were made together with the corresponding environmental measurements and occupant's clothing and bedding information. Subject's thermal sensation was on the cooler side with a preference for warmer environments mostly. People generally felt comfortable, with Griffiths comfort temperature (Tc) being 24.3 C. and 20.2 °C in free-running (FR) and air-conditioned (AC) modes respectively. Adaptive use of air-conditioners was noted. In 82.7% cases in (AC) mode, the comfort temperature was below the lower limit of the international standard. The quality of sleep was good and overall self-declared sleep quality increased with thermal acceptability. Higher depth of sleep was noted when ACs were on. Qatar bedrooms recorded high mean global Pittsburgh Sleep Quality Index (PSQI) score in general (mean = 10.7), indicating good quality sleep. It was higher in free-running mode (mean = 11) than in AC mode (mean 10.4). It increased as subjects liked their HVAC systems, indicating the occupants perception of performance of AC systems affecting the sleep quality. This study highlights the need reduce overcooling in spring and to increase air-movement to enable free-running mode, without reducing the sleep quality.