Abstract
A new hybrid ventilation system for low energy buildings has been investigated theoretically using TRNSYS. The system is based on natural ventilation but utilizes a fan during hours when the natural driving forces are not sufficient. Heat from the exhaust air is recovered in an air-to-water heat exchanger. The heated water is pumped to the incoming ventilation air where it is heat exchanged to preheat the fresh air. Energy from solar collectors is used in combination with heat recovered from the sewage system to heat the ventilation air and to preheat the cold water for domestic use. Results from the TRNSYS simulations show that the bought annual auxiliary energy need for the new hybrid ventilation system is lower than for a conventional fan driven ventilation systems using air-to-air heat recovery units combined with an identical solar collector and sewage heat recovery unit. Since the new system is based on natural ventilation it is also more silent compared to standard mechanical ventilation systems.
