P2. Assment And Field Testing Of Ventilation Recovery Heat Pumps > Background

The heating and cooling loads associated with providing ventilation can be a significant portion of the energy requirements in commercial buildings. There are several approaches to reducing these loads, including the use of demand-control ventilation and heat-recovery heat exchangers. Recently, a major equipment manufacturer has developed a heat-pump energy recovery unit specifically designed to operate between the ventilation makeup and exhaust flow streams. During the cooling season, the unit operates to cool and dehumidify the makeup air and rejects heat to the exhaust stream. However, during the heating season, the cycle is reversed, and the unit removes heat from the exhaust stream and rejects heat to the makeup air stream. It is believed that there is an overall efficiency advantage associated with the use of ventilation-recovery heat pumps as compared with heat-recovery heat exchangers. Under most circumstances, the heat pump cooling and heating rate would exceed the energy gains or losses associated with ventilation. As a result, the loads on the primary equipment would be less than those associated with heat recovery heat exchangers. For cooling, both the sensible and latent loads would be reduced. Furthermore, the heat pump would most likely have a higher efficiency than the primary equipment due to more favorable operating temperatures.

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