| Budget Amount *help |
¥3,740,000 (Direct Cost: ¥3,500,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Research Abstract |
The hygrothermal performance of houses is recently being required to indicate quantitatively due to the encouragement of energy conservation. Several calculation methods are practically proposed to evaluate energy saving measures of houses. However, those methods do not take into account moisture transfer in wall assemblies. Humidity calculation is simply affected by ventilation and focuses on just the building spaces. Then the potential influence of moisture sorption and desorption of walls on the space conditioning load is clarified in Sapporo, Tokyo and Fukuoka, in which the climate conditions are distributed from cold to seasonally sultry, through the comparative numerical experiments utilizing the simulation software of the hygrothermal environment of whole buildings based upon detailed physical models on heat and moisture transfer and airflow. Moreover, the influence of heat storage materials utilizing PCM (phase change material) on the thermal environment is considered through t
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he sensitive analysis. The major results obtained are listed below.
Compared to the detailed calculation taking into account moisture transfer in wall assemblies and the conventional simplified calculation adding the hypothetical moisture capacity into the indoor air to approximate moisture sorption and desorption of walls, the calculation error of the total heat load and the latent heat load for space conditioning accounts for over 10% and 30% respectively. The error becomes larger in the high hygrothermal set-point for heating and in the low hygrothermal set-point for cooling. The influence of moisture sorption and desorption of walls is unable to disregard to predict the space conditioning load.
The simplified calculation assuming the moisture capacity of indoor air is commonly used value, 16.7g/(m3.kg/kg(DA)), estimates the latent heat load quite large. The hypothetical moisture capacity, which is the essential requirement of Housing Performance Indication Law in Japan, may be error cause although the error amount is changed by conditions of heating/cooling and building specifications.
The latent heat load for both heating and cooling of the detailed calculation marks the maximum value at the start of space conditioning and decreases gradually with time. As the moisture is stored up into the wall assemblies at the time of natural conditions and especially impacts the latent heat load at start of space conditioning due to moisture sorption and desorption of walls, the calculation error between the detailed and simplified calculation becomes larger in intermittent space conditioning compared to all day space conditioning.
The interior material with PCM can alleviate indoor temperature change within a temperature range of the phase change ; particularly in case it is used at the building envelopes such as exterior walls, ceiling and floor. Term heating and cooling load is most reduced if a melting point of PVM is equal to the preset temperature for space conditioning. The heat load reduced more as the capacity of PCM increases. Less
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