Hybrid ventilation retrofit in a school setting.

States that hybrid ventilation systems use the strengths of both mechanical and natural ventilation strategies. In the absence of many studies of the operational experience or performance monitoring of the systems, an school in Sweden was retrofitted with a hybrid ventilation system controlled by a building energy monitoring system. The main ventilation power source for this system was the six metre high solar chimneys, which were equipped with low-energy exhaust fans to supplement stack effect where necessary. The monitoring exercise showed that the hybrid system provides a good indoor environment with low energy consumption. Short periods of time in which carbon dioxide levels exceeded 1000 ppm were noted, however.