Summer sleep quality and change of bedroom thermal environment – from the beginning to the end of sleep

Relations between bedroom thermal environment changes and subjective sleep quality and thermal comfort were surveyed for 63 apartment occupants during midsummer in Osaka. Changes of Wet Bulb Globe Temperature (WBGT) of 123 air-conditioned and 41 naturally ventilated nights were compared. 1) For air-conditioned bedrooms, sleep quality was better for smaller changes of WBGT from the beginning of sleep and for faster changes of WBGT to constant from the beginning of sleep. 2) For naturally ventilated bedrooms, a) WBGT increased from the beginning of sleep and decreased toward the end of sleep for higher sleep quality nights. However, WBGT decreased from the beginning of sleep and increased toward the end of sleep for lower sleep quality nights. b) The WBGT change was smaller for thermally comfortable nights

Simplified Prediction Method of Vertical Temperature Distribution for Impinging Jet Ventilation System

The impinging jet ventilation (IJV) system is an air-distributing strategy to generate a thermal stratification in a room by supplying the air vertically toward the floor, which provides higher ventilation effectiveness than mixing ventilation. To date, however, no simplified prediction model of indoor thermal environment for an impinging jet ventilated room has been established. Therefore, this study aims to propose a simplified calculation model based on “Block Model”. This paper first presents a parametric study using Computational Fluid Dynamics (CFD), where total supply airflow rate of a test room is changed as a parameter. The number of terminal is also changed. Secondly, the paper presents the simplified calculation model of vertical temperature distribution based on block model that solves heat flow by advection and diffusion. Here, in this prediction model, the most important parameter is the turbulent thermal diffusivity between two room-space blocks in vertical direction. The room-space blocks are classified into two types, i.e., lower and upper part of a room. Based on parametric study using CFD, turbulent thermal diffusivity is arranged for lower and upper block respectively, and it is finally shown that the vertical temperature distribution from block model well agrees with CFD result