Building pressurization through powered supply equipment provides a ventilation assist to the natural system increasing the ventilation rate of the natural system. Supply air can be placed where needed, penetrating deep into the plant, and eliminating ventilation dead zones in a facility. Strategically placed natural outlets promote building exhaust and do not allow the hot air and fumes an opportunity to build up. This build-up is what creates poor ventilation conditions and haze in a building.

A gravity opening is self-adjusting to the airflow in the building. If the airflow increases, the velocity of the air through the gravity opening simply increases to handle the additional capacity. Thus, the capacity of the ventilation system could be doubled without ever going on the roof again. If a hot spot is created in the plant, appropriate intake equipment can be added in that location.

With a roof exhaust fan system, every time more air is required, an expensive and difficult roof modification must be made. Additionally, with a roof exhaust fan, the results are negligible because the supply air will not be introduced into the hot spot.