摘要:Recently, since global warming has continued, reduction of greenhouse gas CO2 is required. CO2 emissions in the civil area sectors in Japan account for approximately 30%, which is about one-third of the whole of Japan. Therefore, reduction of energy consumption in houses, office and etc. is obviously required. In order to reduce energy consumption of buildings, high-efficiency of machinery, high-insulation, high-airtightness, and use of renewable energy are mentioned. Especially, use of geothermal energy which has almost constant temperature throughout the year has been drawing attention. However, in case of geothermal ventilation system, a fungi, dust, pollen and etc. derived from the outside air are taken directly into the pipe. It is concerned that they cause contamination inside the pipes and breeding of molds, which may lead to odors. The present study analyzed the contamination degree of the pipe surface in the geothermal ventilation system and proposed cleaning frequency in the pipe, cleaning method and so on.