Effects of Attic Air Ventilation, Insulation and Sunshading on Living Pleasantness

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Attic air temperature of wooden houses usually rises more than 50 ^ﾟC during daytime in the summer season, and this causes a temperature rise in the rooms underneath the attic space. The common countermeasure for this problem is ventilation of attic space. Especially, forced ventilation of attic space with fan is expected to be effective on heat exhaust and lowering the temperature of the space. So this effect was examined quantitatively by the field measurements of two individual wooden houses (One is 2 x 4, and the other was constructed by Japanese traditional method) in Kagoshima City from 1989 to 1990. Based upon the measurements of attic air temperature and amount of air change of attic space as well as air temperature of the ceiling underneath the attic space, the following results were obtained :1. Fan is effective when attic space is air tight and amount of natural air change is small. When the Amount of natural air change exceeds 4 (times/h), fan is no more effective on lowering attic temperature.2. Even if attic space is well ventilated, attic temperature is higher than outdoor temperature by 3 to 5 ^ﾟC. To lower attic temperature to outdoor temperature, roof insulation should be necessary. The thickness of the insulation should be decided taking into account intensity of solar radiation.In addition to the field measurements, K- epsilon turbulence model was introduced to analyze attic air distribution. Both isothermal and non-isothermal situations with forced ventilation were simulated. The influences of inlet and outlet locations and their sizes