Proton exchange membrane fuel cells heat recovery opportunities for combined heating/cooling and power applications - ScienceDirect
DIY Heat Recovery Kits
Heat recovery ventilation - Wikipedia
ECONET ® heating and cooling transfer
VRV (Multi-Split Type Air Conditioners) | A multi-split type air conditioner for commercial buildings to provide customers with the individual zone control ability in each room and floor of a building.
Six Steps to Success with Heat Recovery Ventilation - Zero Energy Project