開放系住居の夏の環境特性 : 町家の冷気積層型の上方開放空間

Abstract

There are two types of traditional wooden house "Noka" and "Machiya" in Japan, which have many wisdoms to make them cool in hot and humid summer. The purpose of this study is to find out the mechanism and seek the way to apply them to the modern house which has thick insulation. Although the large horizontal openings and cross ventilation are the distinctive thermal features of Noka in rural area together with thick thatched roof, deep eaves and naked earth floor, it is not practical to apply them to the modern house in a city. On the other hand the typical town house Machiya, which is the subject of this study is characterized by its vertical openings. Although the Machiya had been built very closely to each other, facing to the paved street and surrounded by roof tiles under the burning sun, there are also found refreshing soft winds in their living spaces. The authors tried to find out the cause of this attractive mechanisms with careful observations, inquiries and physical measurement. The results are as follows ; *A typical Machiya house has two gardens ; small court yard "Tsubo-niwa" and back yard "Ura-niwa" at the both ends of living spaces. *The living spaces are open to these closed yards which are open to the sky. *Living spaces are shaded to the sun by deep eaves, straw blinds and dense trees in the yard. So the living spaces are dark in the day time. *Common walls between the two houses and store rooms on the upper floor isolate the heat from outside as if they had thik insulation. *Warmed air is removed naturally upward through both yards and "Tori-niwa" which is a passage of high ceiling with the opening at the top. *Cooled air from the naked ground at the yards and crawl space under the floor fill the living space like a pool. *In spite of heated breeze on the roof, its fluctuations induce delicate change of air pressure difference between two yards and brings ever changing swings of cool air in the living spaces. Although the Machiya has no insulation at all, it has the same thermal characteristics as the insulated houses at least in summer. This idea of upward opening gives an important suggestion on natural cooling of insulated houses even in cold region.