Energy

Positive pressure/forced air systems bring air inside to create a positive, internal pressure that forces air movement outwards. The air will leak out through gaps and open doors and windows.

The supply air flow rate must be higher than the leakage air flow rate and the more airtight the home, the more effective the system.

Note: Ducted warm air transfer systems that take warm air from the roof space or some other interior space also increase the internal pressure and rely on the raised internal pressure to force leakage of stale indoor air to outside