Abstract: With reference to FIG. 3, the sloping roof (250) of a building (10) incorporates inner and outer juxtaposed metal panels, (15, 16) spaced from each other to define passageways (20) which serve as heat exchangers. A closed-loop water circulation system (18) connects the passageway (20) with low, medium and high grade heat store chambers (21, 23, 25) disposed within the building foundation structure (13). The water circulation system (18) employs sub-systems (22, 29 and 31) which comprise, respectively, primary, secondary and tertiary sub-systems. The heat store chamber (21) comprises a portion of the primary circulation sub-system (22) whereby water is re-circulated through the panel passageways (20) so as to be raised in temperature 20 by solar heat. In addition to the heat store chamber (21), the primary sub-system (22) comprises a heat pump unit (27).

Abstract: A building comprises hollow, load-bearing structure, the interior of the structure defining ducts, exterior panels carried by the structure in heat-conducting relationship with the panels, a heat sink, and a heat pump. Water is circulated through the interior of the hollow structure so as to extract solar and other ambient heat from the panels and to transfer this useful heat to the heat sink.