Patent ID: 7878236

Claim:
An improvement for conserving energy in an HVAC system in which ambient air is supplied by the system to a building through an ambient air intake airstream and is exhausted from the building through an exhaust airstream, and heat is transferred between the intake airstream and the exhaust airstream by a heat exchange fluid circulated through a fluid circuit by a heat exchange fluid pump between an intake air heat exchanger located in the intake airstream and an exhaust air heat exchanger located in the exhaust airstream, the improvement comprising: an air turbine placed in one of the intake airstream and the exhaust airstream for being driven by a corresponding airstream, the air turbine being coupled with the heat exchange fluid pump such that upon being driven by the corresponding airstream, the air turbine will, in turn, drive the heat exchange fluid pump in proportion to a volumetric flow of the corresponding airstream to circulate the heat exchange fluid between the intake air heat exchanger and the exhaust air heat exchanger and thereby effect the transfer of heat from one to the other of the intake airstream and the exhaust airstream and a concomitant conservation of energy in the HVAC system.