The effects of programmed air temperature changes on sleep quality and energy saving in bedroom

• Published in: Energy and buildings Vol. 129; pp. 207 - 214
• Main Authors: Lan, L., Lian, Z.W., Qian, X.L., Dai, C.Z
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.10.2016
• Subjects: Air conditioner; Bedroom; Energy saving; Sleep; Sleep quality; Thermal comfort; Sleep quality; Thermal comfort; Sleep; Energy saving; Bedroom; Air conditioner
• ISSN: 0378-7788
• DOI: 10.1016/j.enbuild.2016.08.001

•The effects of programmed air temperature changes on sleep quality and energy saving in bedroom were investigated.•No significant difference in sleep quality was found when the air temperature changed in the range from 26°C to 28°C.•A slight increase of air temperature during the later period of sleeping could better prepare the body for wake up.•The total cooling load is reduced by 27.8% in the Rise-Fall condition and 34.3% in the Fall-Rise condition. Bedroom air-conditioning is often programmed to cause the air temperature to follow either a Rise-Fall or an inverted Fall-Rise shaped course during the night, and there are rational arguments for both. The effects of these two programmed air temperature changes were investigated by creating three thermal conditions: a reference condition with constant temperature (26°C), a Rise-Fall change condition (26°C–27°C–28°C–27°C–26°C), and a Fall-Rise change condition (28°C–27°C–26°C–27°C–28°C). Twelve healthy young people (6 females and 6 males, mean age 23 years) slept in a climate chamber with multiple of their physiological parameters monitored continuously. No significant difference in thermal comfort or sleep quality was found among the three conditions. The subjects had better next-day performance in the Fall-Rise condition than in the other two conditions. Simulation results show that compared with the reference condition, the total cooling load of a simulated bedroom is reduced by 27.8% in the Rise-Fall and 34.3% in the Fall-Rise condition. These results indicate that a slight increase of air temperature within thermal comfort range during the later period of sleeping (as simulated in the Fall-Rise condition) could better prepare the body for wake up, and also could save energy.