Abstract
In this study, the microclimate of the test room was regulated using thermoelectric air duct cooling system (TE-AD) operated at input powers-240 W, 360 W, 480 W, 600 W, 720 W, and 840 W, on subsequent nights. Fifteen (15) healthy male volunteers were recruited to sleep under these test conditions and their sleep quality was assessed by studying objective measures such as sleep onset latency (SOL), mean skin temperature and heart rate as well as subjective parameters like predicted mean vote (PMV) and predicted percentage of dissatisfied (PPD). There was a consistent improvement on all studied parameters when the power of the system was increased from 240 W to 720 W. The mean sleep onset latency time was reduced from (M = 40.7 +/− 0.98 min) to (M = 18.33 +/− 1.18 min) when the operating power was increased from 240 W to 720 W, denoting an improvement in sleep quality. However, increasing the power further to 840 W resulted in deteriorating cooling performance of the TE-AD system leading to an increase in temperature of the test room and reduction in sleep comfort. Analysis of subjective indices of thermal comfort viz. PMV and PPD revealed that subjects are highly sensitive towards variations in microclimate achieved by changing the operating power of the TE-AD. This device was also found to be environmentally sustainable, with estimated reduction in CO2 emission calculated to be around 38% as compared to the conventional air-conditioning.
Highlights
Adequate sleep is important for maintaining a healthy and productive lifestyle
This study investigates the effects on sleep quality and thermoregulation in test-room conditions when the thermoelectric air duct cooling system (TE-AD) framework is operated at variable power inputs in a tropical climate setting
This research analyzes the subjective and objectives parameters of sleep quality of volunteer-occupants who slept in a test chamber with a TE-AD framework operated at six pre-determined levels of input supply, i.e., 240 W to 840 W
Summary
Adequate sleep is important for maintaining a healthy and productive lifestyle. Impaired quality and reduced duration of sleep may lead to serious short-term and long-term health and related consequences [1]. This can range from increased risks of obesity, Type-2 diabetes to a spectrum of cardiovascular ailments [2]. Studies have linked lack of adequate sleep to workplace injuries and Energies 2019, 12, 3695; doi:10.3390/en12193695 www.mdpi.com/journal/energies. Energies 2019, 12, 3695 road traffic accidents [3]. Indoor thermal environment affects the sleep comfort of the occupants [4]. Quality of sleep is strongly linked to the thermal microenvironment as established by several studies [5]
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