Adequacy of air-to-air heat recovery ventilation system applied in low energy buildings

Dwellings represent more than 40% of final energy consumption in France. They also present the highest potential of energy savings, while using technology already substantiated, without huge investments, in contrast to other sectors. Ventilation is one of the main sources of heating loss in buildings, so recovering heat from exhaust air could reduce significantly heating loads. In airtight and well insulated buildings, heat recovery ventilation (HRV) systems are often recommended to save heat energy. However, these savings should be balanced against the electrical power requirements of the fans. A HRV unit is modeled, using TRNSYS, and studied in order to characterize its annual performance when integrated into residential and commercial low energy buildings. The energy performance of HRV is compared to one of the standard ventilation systems. This comparison is based on the heating, cooling and ventilation primary energy consumption for different climatic zones. It is found that the adequacy of using HRV system depends on the building types, the heating loads and ventilation device characteristics. A sensitivity analysis by simulation is undertaken to investigate the influence of exchanger efficiency and specific fan power on the global energy performance of the HRV system.

► Heat recovery ventilation performance is compared to other ventilation systems.
► It is more efficient than mechanical extract ventilation system in dwellings.
► In commercial buildings it is less efficient except in cold climate.
► Heat recovery performance is compared to humidity controlled ventilation.
► It's benefit is questionable in residential buildings for the French climate.