Patent attributes
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 energy is conserved by transferring heat between the intake airstream and the exhaust airstream. A heat exchange fluid is circulated between heat exchangers located in the intake airstream and in the exhaust airstream. An air turbine is placed in the exhaust airstream for being driven by the exhaust airstream, and the air turbine is coupled with a pump arranged to circulate the heat exchange fluid between the heat exchangers such that upon being driven by the exhaust airstream, the air turbine, in turn, drives the pump to circulate the heat exchange fluid between the heat exchangers and thereby effects 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.