To provide a system for achieving a comfortable dwelling environment temperature by using a base slab for a heat accumulation layer, by directly collecting geothermal heat to accumulate it, and compensating shortage of the amount of accumulated heat by a hot-water heating heat source machine in order to solve high cost of excavation such as boring, high heat exchange facility cost, shortage of heat quantity due to low underground temperature in the winter period all of which make geothermal heat utilization of a house in a cold area difficult.

A base slab is used for a heat accumulation layer, the heat accumulation layer and a building are integrally heat-insulated from the outside air and an underground surface layer part, and the geothermal heat is efficiently collected and accumulated without executing large-scale excavation. This system is characterized in that a hot water circuit is arranged in the heat accumulation layer for compensating the low underground temperature in a cold area, heat accumulation is assisted by a heat source machine, and a radiator and a duct for equalizing the temperature in the building are installed.