Impact of hybrid ventilation and sewage heat recovery on the energy performance of a low energy building; a feasibility study

A hybrid ventilation system including sewage heat recovery for low energy buildings has been investigated using TRNSYS. Energy from solar collectors is used in combination with the heat recovered from the sewage system to preheat the ventilation air and the cold water for domestic use. Results show that the new system renders a possibility to use natural ventilation in passive houses and zero energy buildings. The annual auxiliary energy need for the new system is lower than for a conventional fan driven ventilation systems using air/air heat recovery units. Depending on technical solution and site of installation, the system can provide free cooling during the summer. Since the new system mainly runs on natural forces it is also more silent compared to standard mechanical ventilation systems. (Less)