We present a Crawl-space heating with thermal storage. It is a heating system using the crawl space of foundation-insulated houses with no underground room as a duct for heat transport and as a space for installing the thermal storage equipment. We used a heat pump as a heat source and sensible thermal storage materials for heat storage. The thermal storage equipment is charged by the heat pump by using cheap off-peak electricity and it is discharged into the crawl space at daytime. We conducted experimental studies and it is revealed that thermal behavior of the room is greatly influenced by the quantity of charged and discharged heat and the change of the room temperature can be made moderate by increase the quantity of the stored heat.