The space pressurization technique has been widely utilized in building HVAC design to either direct a desired flow pattern or to isolate air cross-contamination. This technique is especially critical to environmentally controlled space design.

However, one of the key questions of how to determine the pressurization ratio for a space with leakage flow through irregular cracks or through an open door has not yet been explored quantitatively. Due to lack of practical guidelines, unreliable guesswork was often applied toward design.

This paper is mainly focused on the establishment of the relationship between a space’s pressurization ratio and its air leakage flow. By numerical approximation, it is found that each room’s pressurization ratio can be estimated based on the room’s effective leakage area (ELA) and the pressure difference (DP) across the room shell, and the pressurization ratio for a space (zone level with multiple rooms) can also be determined. The pressurization design for environmentally controlled spaces can then be more predictably achieved.

Units: Dual