Abstract: A building structure includes a plurality of structural load bearing wall portions in thermal contact with the external atmosphere and further load bearing means located inside the building structure in thermal contact with the internal atmosphere of the building. The structural load bearing wall portions are formed by a plurality of liquid tight, hollow load bearing panel members for the flow of a liquid at a preselected temperature therethrough. Each of the panel members includes inlet means for the introduction of liquid therein and outlet means for the removal of liquid therefrom. The panel members and their inlet and outlet means are arranged and connected in fluid flow relation to provide a predetermined flow pattern of the liquid through the load bearing structural wall portions. Pumping means are connected in fluid flow relation to the panel members for forcing liquid through said wall portions.