Abstract: Apparatus for providing more efficient use of heating and/or cooling sources as used within a building structure, particularly residential type buildings. In essence, this system utilizes a wood-burning fireplace in coactive conjunction with a standard form of building heater system, gas, oil or the like, and it functions to provide an integrated system having greater efficiency, and therefore greater fuel conservation. The fireplace includes a plurality of heat exchange chambers through which ambient air is pulled by the central system blower for subsequent recirculation through the heat register or release vents and, as temperature controls will dictate, central system heat may or may not be additive therewith. More efficient cooling is effected in like manner by coaction of a cooling system with the fireplace plenum chambers to provide a continual source of cooled air for contributive use with the central cooling system.