A two-part model for evaluation of thermal neutrality for sleeping people

A thermally comfortable environment is important for sleep quality. Conventional thermal comfort models may not be able to predict and assess the optimal environment conditions for humans in sleep. By dividing the human body into two parts - one in contact with a bed and the other not, and based on the principles of heat balance of the human body, a model was developed to predict the thermal neutrality of sleeping people. Using this model, the sleeping thermal environment was classified into four categories that related thermal load of body to sleep quality. The results calculated with the present model agreed well with the experimental results. If the bedding system and the four thermal parameters in the room, including air temperature, relative humidity, air velocity, and mean radiant temperature, are given, the model can evaluate whether the sleeping people is in thermal neutral. On the other hand, it can be used to calculate the values of the four thermal parameters that need to maintain the thermal environment as required. This model will serve as a useful tool for evaluation, design and control of an optimal thermal environment for sleep, as well as design of innovative heating and cooling systems for sleeping environments.