To solve a problem wherein high temperature water by a petroleum boiler consumes excessively energy, and imparts an excessive load to human metabolism, and a problem wherein a comfortable heating system for the human metabolism capable of reducing a energy consumption has to use low temperature water as supply water for heating and to secure dwelling house performance (high density/high heat insulation) allowing the heating under this condition, and to construct a comfortable healthy heating for the human metabolism capable of reducing the energy consumption to the utmost, by systematizing three elements of an underground heat source using heat pump, a high density/high heat insulation dwelling house and the heating by the low temperature water.

The low temperature water is provided using the underground heat source heat pump to be supplied as hot water for the heating. A dwelling house is constructed of the high density/high heat insulation dwelling house, and a heat exchange area of a terminal heat radiator is secured as wide as possible. A pipe is embedded in a foundation floor slab to be utilized as a regenerative heat exchanger.