09. Heat and Mass Transfer

Improving the thermal insulation performance of buildings is necessary to promote low-carbon policies. In this study, we aimed to verify the thermal insulation performance of buildings with wooden exteriors in cold regions, and evaluated the thermal insulation performance of full-scale buildings using data measured over a long period of time. The subject of the measurements was the Yonezawa City Library, a five-story reinforced concrete building constructed in Yonezawa City, Yamagata Prefecture, Japan. Heat-treated thinned cedar walls are installed on the outside of the reinforced concrete walls. Surface temperatures and heat fluxes of the wall components and window glass were measured. Air temperature and humidity were measured inside the library, and outdoor weather conditions were measured inside the library. The total daily power consumption of the entire library was also measured. Daily changes in wall temperature were large for the exterior components, and a decrease in daily change and standard deviation was observed toward the interior components. Measurements of daily changes in wall heat flux showed that heat flowed from the building to the outside in winter and from the outside to the building in summer. The smaller change and standard deviation of the interior heat flux compared to the exterior of the wood envelope indicates the insulating properties of the wood envelope. Electricity consumption peaks in summer and winter. A correlation was found between the power consumption and the temperature difference between inside and outside in winter, and between the power consumption and the absolute humidity difference between inside and outside in summer. It was found that heating is the main method of maintaining the temperature inside the building in winter, and that in summer, when there is almost no thermal load from the walls, dehumidification to maintain humidity is the main method of maintenance rather than air conditioning to maintain temperature.