Field Survey of Thermal Comfort and Sleep Quality in the Bedrooms with Different Cooling Strategies in Malaysia

Abstract

This study aims to determine the indoor comfort temperature before sleep and after wake up in air-conditioning (AC) mode with different adaptive cooling strategies. Two units of guest rooms on the university campus were used with a total of 20 participants. The arbitrary-controlled AC setting (case 1) and control of thermostat setting by 3∘C higher than case 1 with installing of cool bed padding (case 2) were employed as cooling strategies in this study. The measurement parameters were indoor and outdoor air temperatures, globe temperature, relative humidity, air velocity, and AC electricity consumption. The questionnaire survey has also been distributed twice a day for “before going to bed” and “after waking up” during measurement simultaneously. It was observed that thermal sensation vote (TSV) indicated for both cases were within -1 ≤ TSV ≤ 1 and respondents might accept the present condition for both cases. Mean thermal preference (TP) in both cases either “before going to bed” and “after waking up” was found mostly close to “0 no change” (0.1 ≤ TP ≤ 0.3) for all cases. Overall comfort (OC) ranged between 4.7 and 4.9 for both cases, indicating for “comfortable.” However, air movement sensation (AMS) shows respondent felt weak airflow inside the room for all ventilation strategies. The skin moisture sensation (SMS) shows value pointed to neutral feeling for all cases. The comfort temperature obtained by Griffiths’ method was approximately 24∘C and 25∘C that for case 1 and case 2, respectively. Meanwhile, most of the respondents experienced calmness during sleeping and satisfied with their sleep in both cases. Sleep efficiency index (SEI) shows case 2 was higher rather than case 1. It seems the second adaptive cooling strategy might effective for reducing AC energy consumption by about 32% and increase 2% of SEI without affecting respondents’ thermal comfort.