The advantages of a hybrid ventilation concept for schools

Hybrid ventilation as a combination of natural and ventilation provides opportunities to use the different advantages of both ventilation systems during the seasons in order to reduce energy demand and obtain comfortable indoor climate at the same time. For this study a comparison of a natural, mechanical and hybrid ventilation system applied to a school building has been made by means of detailed modeling. The energy demand for heating and ventilating the building in the different ventilation modes was calculated for three climate zones in Europe, Copenhagen, Munich and London. Control strategies were set to obtain the same indoor climate for all ventilation modes and to fulfill the requirements of EN 15251. The modeling of the hybrid ventilation system resulted in a primary energy demand for fans electricity and heating of 10-11 kWh/m² per year in all three locations. Compared to that, natural and demand-controlled mechanical ventilation resulted in a primary energy demand of 18-21 kWh/m² per year in Munich and Copenhagen and 16-18 kWh/m² per year in London. This proves energy savings of about 50% for the combination of the systems compared to the single ones.