Study on Seasonal Ground Heat Storage of Solar Energy Using a Vertical Pipe System : Part 4-Calculation of Indoor Temperature, Soil Temperature, Heat Storage Rate and Heat Recovery Rate

Abstract

An indoor temperature, a soil temperature, a heat storage rate and a heat recovery rate with long term ground storage under a test house were calculated. In case of the natural heat recovery method, the minimum indoor temperature at the test house dropped to 0℃ in the coldest season in Sapporo. The effect of the long term heat storage on the indoor temperature rise was not sufficient. In the mechanical heat recovery method using a heat pump, the amount of heat extracted from the soil was larger than that of the heat stored. This was caused by the heat recirculation between the house and the soil and the direct heat gain which could extract from the soil using the heat pump without the heat storage. The heat recovery rate was about 0.97 when the insulation at the ground surface was installed. It was found that the high level insulation between the house and the soil is necessary.