Passive Ventilation by Thermal Convection in Insulated Houses Using the Thermal Concepts of Traditional Japanese Houses in Summer

Abstract

Traditional Japanese concepts for comfortable living in the summer include the use of the thermal convection ventilation by exhausting warm air at the ceiling level. Generally outdoor temperatures during the summer months in some regions, including Hokkaido, can reach 30 ° C in the daytime, but those at night can be very cool. The convection rates of the exhausted warm air and the inflow of cool outdoor air through open windows located in the upper levels of a test house were measured throughout the day by using CO₂ as a tracer gas supplied to the bottom zone of the space. The gas concentration in each of 5 zones was simultaneously measured, and the airflow rate between each zone and the others was calculated. It was confirmed that the technique is useful for measuring convective airflow rates and processes through upward openings, such as open windows, and that the vertical ventilation exhausts the stored heat of 1 kW. It was concluded that, for the purpose of energy conserva tion, architects and engineers should consider the utilization of passive venti lation by thermal convection in the summer in highly insulated houses located in cold regions.