Controlling Building Pressure

Welcome to All Sensors “Put the Pressure on Us” blog. This blog brings out pressure sensor aspects in a variety of applications inspired by headlines, consumer and industry requirements, market research, government activities and you. In this blog we’ll discuss proper indoor versus outdoor pressure in commercial buildings.

Controlling Building Pressure

Proper indoor versus outdoor pressure is important in commercial buildings. When indoor pressure is less than the outside pressure, outdoor air leaks, or infiltrates into the building. In addition to impacting heating, ventilation and air conditioning (HVAC) effectiveness, excessive infiltration can also cause uncomfortable drafts, especially in stairways, as well possible odor migrations and even encourage microbial growth depending on the outside weather conditions.

The opposite pressure condition, exfiltration, occurs when indoor pressure is greater than the outside pressure, indoor air leaks out of, or exfiltrates from the building. Excessive exfiltration negatively impacts temperature control by reducing supply airflow into occupied spaces, makes opening and closing doors difficult and creates noisy high-velocity airflow around doors and windows.

In addition to the operation of its mechanical ventilation system, a building’s pressure can be positive or negative due to the impact of wind and weather. Using either a return fan or a relief fan, for direct control of building pressure, manages the combined effects of weather, wind, and mechanical ventilation. This control requires pressure sensors mounted inside and outside of the building to determine the actual pressure difference. Depending on the desired exfiltration and infiltration goals, the pressure difference is typically less than 0.1-inch water gauge (wg) and can be either positive or negative.

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Do you have a pressure sensing question? Let me know and I’ll address it in an upcoming blog.
-Dan DeFalco, Marketing Manager, All Sensors Corporation (