Building pressurization, either negative or positive, isn’t typically known or felt when you are standing inside your building. There are symptoms of buildings with pressure problems. We will get to that in a bit… but how does it happen?
Below are three samples showing how we get to different building pressure conditions. In this simple example, we have an air handling unit and exhaust fan located on the roof of the building. In these examples, air flow in the building is shown in green arrows and air flow out of the building is shown in red arrows.
In our first example, we have an air handling unit providing more air from the outside than is being exhausted from the exhaust fan. When this happens, we begin to positively pressurize the building with more and more air from the outdoors. This is fairly common in systems that deliver high amounts of outside air. Do you have a building served by evaporative coolers? What about units with economizers? If means of removing or releasing the extra air have failed or were not implemented, you can expect…
- Doors not closing or latching
- Whistling around your doors
- Feeling of hot or cold air, depending on season, coming out around your doors
- Roof blistering
In our second example, we have an air handling unit providing almost equal air from the outside than is being exhausted from the exhaust fan. When this happens, we expect the pressure inside this building to be fairly close to neutral. When your building was first designed, it was likely laid out to maintain a neutral to slightly positive air pressure. You shouldn’t see any of the symptoms shown above. When your building is operating at the right pressure you can expect your building to function the right way.
In our third example, we have an air handling unit providing less air from the outside than is being exhausted from the exhaust fan. When this happens, we begin to negatively pressurize the building by removing more air than is being added. When this happens to your facility, it can really make temperature control a problem. When your building is negatively pressurized, expect air from the outside to make its way into the building. If it’s 110 degrees outside expect this air to come into your building through any available path and really rush in when you open a door. Depending on the severity, it can make it difficult to maintain building temperature and even humidity levels. Some signs of a negatively pressurized building include…
- Hard to open doors
- Rush of air when opening a door
- Higher energy costs
- Hot and cold spots
- Humidity control issues
If any of this is consistent with your building, understanding the symptoms is the first step to solving the problem. There are many things that need to be considered and investigated to solve the problem. If any of this plagues your facility, we can help!