What causes a Pressure Delta?

A Pressure Delta refers to the difference in air pressure between two points in a building or a system. This phenomenon primarily occurs due to air movement, which can be driven by various factors such as wind, changes in temperature, or the operation of ventilation systems. When air moves from one area to another — whether through openings, ductwork, or gaps — it results in a difference in pressure.

For instance, if a room is being exhausted at a higher rate than air is entering, a negative pressure delta is created in that room, leading to draft issues or even air quality problems. Conversely, positive pressure deltas can occur when air is forced into an area. This understanding is critical in multifamily buildings, as maintaining balanced air pressure can impact energy efficiency, indoor air quality, and overall comfort for residents.

While temperature changes, structural elements, and humidity levels can influence the overall building performance and may indirectly affect air movement, they do not directly cause a pressure delta. Instead, they may be contributing factors that impact how air moves through a space, rather than being the primary cause of the pressure difference.