(under subclass 617) Apparatus wherein the material includes a relatively hard naturally formed mass of mineral or petrified matter or earth. [figure] [caption]A double-walled structure utilizes air as the heat transfer medium between solar-heated outer walls and either the interior space or heat storage means beneath the structure. A load-bearing layer of gravel supporting the floor and subterranean gravel pits form the heat storage means. In summer, during the day, solar-heated air gives up heat to the storage means; at night, heat is radiated to the atmosphere and thus-cooled air is used for daytime cooling by storage either in the gravel pits or the gravel layer supporting the building floor. In winter, air is heated in the storage means for interior circulation and, when available during daylight hours, solar-heated air may be used directly or temporarily stored for nightime use. Cold air can also be stored during winter months in separate storage means for additional summer cooling capacity.
(1) Note. A patent proper for this subclass will have at least one claim wherein the material is identified as being rocks or stones, or being a combination, or fragmented rocks
