Heat recovery in an air-conditioning system with air-to-air heat exchanger

In comfort applications, air-to-air heat exchangers (HEs) lower the enthalpy of the building supply air during warm weather and raise it during cold, by transferring energy between the outdoor ventilation and exhaust airstreams. In this paper, a 250 person capacity auditorium located in Thessaloniki, Greece, is used as a model to calculate (i) the heating and cooling energy that can be recovered, (ii) the reduction in heating, ventilation, and air conditioning equipment, and (iii) the expected payback period from the installation of a fixed-plate, cross-flow HE in the air-handling unit of the system. An energy analysis with the modified bin method energy calculation was used to compare the energy consumption with and without HE, and with full or half occupancy. It is proved that, at the climatic conditions of Thessaloniki much more heating than cooling energy can be recovered and that the payback period of the HE is between 1 and 2 years.