How Does Your Home "Stack" Up?

There is constant air movement through your home. There are generally three types of forces that move air through a house: HVAC equipment, wind, and the "stack effect".

The stack effect is when warm air moves upwards in a house. Since we can't create a vacuum in our homes, new air has to come into the home to replace the air that has escaped to normalize the pressure.

Although the stack effect occurs in both the summer and the winter, the effect is usually greater in the winter due to the temperature differential. In the winter, cracks and openings throughout the building shell allow the pressure difference between indoor and outdoor spaces to drive air out of the top floor and to suck air in through the first floor.

In the summer, when indoor air is cooled, the reverse occurs; however, because the temperature difference between inside and outside typically isn't as great as it is in winter, the stack effect isn't as great either.

Whatever the season, the best way to remedy the stack effect in most houses is by minimizing gaps between indoor and outdoor spaces. Think about the places where new air is able to enter the house.

According to the US Department of Energy, the following areas are responsible for a large majority of air leakage that occurs in the average American home:


Ceiling, Walls and Floors – 31%
Ducts – 15%
Fireplace – 14%
Plumbing Penetrations – 13%
Doors – 11%
Windows – 10%
Fans and Vents – 4%
Electrical Outlets – 2%

These figures provide you with the most important areas to target for air sealing. However, a home energy audit will pinpoint the exact locations of air loss and assess your entire home’s energy consumption and waste, and recommend ways to improve your home’s energy efficiency.

Air Matters LLC has performed mold testing services in the Raleigh NC area since 2002. The owner, Renee D. Ward, has over 25 years of safety and environmental experience and holds both her Bachelors and Masters degrees in engineering. Renee is also a member of the American Industrial Hygiene Association and the Indoor Air Quality Association. You may contact Air Matters at (919) 961-2221 or info@AirMattersMoldTesting.com.