Field survey on the comfort temperature and occupant behaviour in bedrooms

Abstract

Sleeping is one of the most important elements of human behaviour in the domestic residence. However, sleep disorders are one of the key issues in recent years. This might be related to the various environmental factors. Sleep disorders involve not only thermal discomfort but can also lead to reduced performance and general health deterioration. To improve the sleeping environment, we need to investigate the thermal environment of bedrooms and thermal comfort of the residents. Thereby, we need to research to occupant behaviour. In this research, we focus on methods of cooling and fan usage, window opening and clothing adjustment. There are some problems when we use the active controls. Especially, we need to minimize the cooling and fan use for energy saving. It is important to consider not only energy saving but also the death rate due to heat stroke when adjusting the thermal conditions. Sometime people may set the cooling temperature without knowing their own comfort temperature very well. Thus, in order to control the indoor thermal environment properly, we need to investigate the comfort temperature of the residents. In order to investigate the thermal comfort, occupant behaviour and depth of sleep in bedrooms, we have measured the air temperature and relative humidity in 10 houses, and conducted a survey of thermal comfort, occupant behaviour and depth of sleep survey with 25 residents, obtaining 3,135 votes. Survey period is from 10 August 2013 to 9 August 2014. The major findings are as follows: 1) The bedrooms' air temperature was very well related with outdoor air temperature in Free Running (FR) mode. 2) The residents feel comfortable expect for winter in FR mode. 3) The comfort temperature was 19.1 C in spring, 27.0 C in summer, 22.9 C in autumn and 16.1 C in winter in FR mode. And, we could express the comfort temperature as a function of running mean outdoor air temperature as one of the adaptive models. This model may prove to be an effective tool for predicting and informing control strategies for the indoor comfort temperature in bedroom. 4) It seemed that the residents use mechanical cooling or heating units with setting off-Timer and they use mechanical fans without setting off-Timer. 5) Difference was observed in occupant behaviour by sex or age. 6) The proportions of mechanical fan, cooling and heating use and window opening as the function of outdoor or indoor air temperature were obtained from Logistic Regression Analysis. 7) There was no distinctive relationship between the depth of sleep given by the subjective votes and indoor air temperature.