To use natural energy such as solar heat and underground heat for air conditioning and hot water supply in facilities and snow melting as a simple and inexpensive system with good thermal efficiency.

This system includes a solar heat collecting board and a solar heat carrying pipe which are simple, are easily mounted on the site and replace a solar heat collector in the general market. As an alternative to a heat storage tank in the general market, soil is used as a heat storage tank, to utilize recyclable energy.