24 May The Importance of Conducting a Negative Air Pressure Test
Question: What is a Negative Air Pressure Test?
Answer: A home inspection test to identify air leaks in the home.
Q: Why would someone conduct a Negative Air Pressure Test?
A: To quickly identify air leaks in a home.
Q: As a home improvement expert, what else do you need to know about it?
A: All the ins and outs!
Why Homes Need Negative Pressure Tests
In an ideal world, all homes would be balanced homes. They would have equal air pressure, impeccable foundations, and strong building envelopes.
Though, as most professionals know, those things can wane as time goes on — a home’s envelope is not always maintained after construction, the air barriers can slowly deteriorate, and air can seep out of the home accordingly.
Air leakage does not only happen in the typical spots our home-owning customers think to look. For instance, under-insulated wall outlets can add more air leakage throughout the entire house.
If something as small as a wall outlet could be such a big problem in the home, it’s only natural for homeowners to ask, “where else is the air leaking in my house?”
If you are a home inspector or technician, you’re aware of the byproducts of the “Stack Effect”. You are also likely familiar with the other usual suspects of air leakage such as scuttle holes, canned lighting, faucets, and windows/doors.
Stack Effect: High & low leakage. Warm air tends to leak out near the top of the house, causing outside air to leak into the house lower down.
What’s important for experts is the ability to find the faults in the home envelope quickly. This is where pressurization tests can come in handy.
Benefits of a Negative Air Pressure Test
Negative air pressure in the home can occur any time of the year and can cause issues year-round.
Summer Problems: Warm air is sucked into the house and wastes air conditioning. This can then cause excess moisture buildup and bad indoor air quality. Mold and allergens can be more prominent, and discomfort can arise in the form of drafts. The homeowner ends up paying for the wasted A/C in increased utility bills.
Winter Problems: Cold air leaks into the home envelope through the same gaps, cracks, and openings as they do during the summer. The homeowner could experience problems from the dry outside air, and higher energy bills can persist in these colder months when the heater is on.
Regardless of the season, air leaks in homes lead to avenues of entry for dangerous air pollutants, often from attics which are the unhealthiest rooms in homes.
When inspectors conduct a negative pressure test, the root causes of these problems can be quickly identified and lead to a healthier home environment. Here are some of the improvements you can create by identifying and addressing negative air pressure:
- Less dust
- Less allergens
- Better indoor air quality
- Less hot and cold spots
- Better energy efficiency
- Lower energy bills
Stopping these issues starts with the right test to find the source of the issues. That is where the negative pressure test comes in.
How To Conduct a Negative Air Pressure Test
Blower Door Test
The blower door test is a common test for identifying negative air pressure.
To conduct this test, technicians will need the right equipment. The following tools are the most commonly needed essentials:
- Blower door system
- A calibrated fan to measure airflow rate
- Smoke pen or smoke pencil (to see the airflow — as air comes in, smoke can be seen moving)
- Infrared camera (Infrared cameras identify areas where unwanted heat comes in (common places include wall cavities, light fixture perimeter, around ducts, and windows and doors)
- Optional: Duct film and/or flow hoods (to cover registers and monitor outside air from ductwork, respectively)
When technicians have the appropriate equipment, conducting a negative pressure test is just a matter of looking in the right places.
Keep in mind that when conducting this type of negative pressure test, technicians will want to make sure they input specific details into the calibrated fan’s computer beforehand. This will allow it to calculate and read back accurate results. Namely, you’ll want to identify the height of the building and account for any wind outside.
NOTE: These guidelines for negative pressure tests should not be conducted by non-certified or approved healthy home professionals. Homeowners or non-certified persons should only conduct blower door tests under the supervised guidance and approval of a certified authority.
To conduct the test, you’ll need to follow these steps:
- Open the home’s front door (or a door that leads outside) and set up your blower door in its place
- Place the calibrated fan properly inside the blower door
- Optional: Cover open vents with your duct film, and use flow hood(s) over registers to measure how much outside air is coming in through ducts
- Turn on calibrated fan and interpret the results on its attached computer screen
- Inspect airflow and temperatures around common air leakage spots with infrared camera and spoke pen/pencil to identify where sealing is needed
The calibrated fan and computer should give you a cubic foot result indicating how much air leakage their is in the home. At that point, it’s a matter using the smoke tool to quickly identify the biggest leakage spots. Run the pen/pencil by the chimney, ducts, exhaust fans, and heat recovery ventilators.
Home Pressurization Test
Another option that home experts have to identify air pressure problems is the home pressurization test. This test can be more done without a calibrated fan, computer, or a blower door.
To conduct the home pressurization test:
- Close all windows, doors, and openings in the home. This includes fireplaces, doggy doors, or any other fenestration.
- Turn off the home’s heating/cooling system
- Turn on all exhaust fans in the home
- Inspect the areas of the home with a candle/incense, a wet hand, or a smoke pen/pencil. Using these tools, you can detect the direction of airflow through the rooms, and determine any openings, drafts, or irregularities which are occuring.
- Take note of which areas show air drifting toward the outside.
Conducting the home pressurization test will help identify air leaks throughout the house. It can help identify spots of both negative and positive air pressure.
Once the air leaks are identified, technicians can recommend any of the solutions listed below to the homeowner, depending on where the leak is coming from and how big the gap is.
Single Room Test
Sometimes you may want to inspect a single room for negative air pressure rather than an entire home. To do so, you will follow similar steps to the whole-home test above, but isolate the conditions to an individual room.
- Seal the room in question. Close all windows, doors, vents, closet doors, or other openings within the room.
- Leave the room and close the door behind you.
- Identify your pressure test point. This will be a single gap in the room’s envelope where you can test for airflow. The test point can be one of two options:
- The gap between the bottom of the door and the floor.
- If there the door is flush with the ground or has weather-stripping, draft dodgers, etc., open the door slightly to create a pressure test point. You do not need to open it further than a ¼”
- Light a candle/incense and hold the flame near the pressure test point. If the smoke visibly drifts toward the opening rather than upward or away from the opening, the room may have negative air pressure.
The solutions needed to solve air leaks in a single room are typically less drastic than those needed for whole-home fixes.
Solutions for the Homeowner
As healthy home experts, it’s important to make sure the homeowner is well informed so that they know how balanced (or unbalanced) their home actually is.
Many homes are lacking in energy efficiency, are wasting air, and the homeowners are not even aware.
It’s important that inspectors and technicians take the proper steps to ensure their client knows exactly what is going on in their home.
Homeowners want a balanced home. That means energy efficiency, a healthy indoor environment, and more comfort. These should always be the end-goal with any test or inspection.
After a test is conducted, having the homeowner feel confident in the future of their home is simply a matter of communicating the opportunities that the test has presented.
After completing a pressurization test, many opportunities to seal the air should jump out.
- Attic access covers
- Ventilation fans
A negative pressure test can be a tremendous asset for inspectors, and it opens up discussion for many other opportunities for better comfort, lower bills, a healthier environment, and higher energy efficiency through insulation and improved ventilation.
Air pressure tests have been a go-to method of testing for professionals over the years. However, there are now emerging alternative methods that healthy home experts are utilizing in their work to create balanced, healthy homes.
Namely, professionals are now using infrared cameras to quickly see the temperatures of surfaces and are incorporating this new technology into their creation of a more balanced home.
In the past, this kind of tool could only read a small portion of the surface and give the user a single number. These older versions were useful, but they were not necessarily required for an inspection.
Nowadays, the technology of these infrared cameras is so advanced that not utilizing one is a disservice to the homeowner.
For example, the Flir gun that many healthy home experts now use is leagues ahead of older models.
Not only does it give you the temperature of an entire surface, but it also generates a color-coded image for easy interpretation of otherwise hidden temperature discrepancies. These guns can also operate from longer distances.
The thermal image on the gun clearly showcases where sealing and insulation could be impactful.
Through these methods, or the more common methods listed above, home professionals can better create a balanced, healthy home that leads to more long-term cost savings and overall comfort.
Interested in learning more?
Yellowblue™ Eco Tech recommends that all tests be conducted by trained professional technicians.
Reach out to us here to learn more home inspection techniques, best in class tools to improve the homes on your jobs, and increase the value you are able to offer.