This effect happens when the warmer indoor air rises up from lower living areas and escapes through the upper openings of a building in much the same way that cross ventilation works. What is cross ventilation? It occurs when people open windows on opposite sides of the house to cool indoor temperatures. If you have central air conditioning, you don’t need to open a window. But letâ€™s get back to explaining the stack effect.
If you stand in front of a fireplace and strike a match, you will see the smoke leave and go up the chimney. This same effect happens in each home. The taller your home, the more stack effect you have in it.
The same effect helps keep your attic cool also. Go outside of your house and look under your soffit to see if you have soffit vents. If you do, you are in great shape. The air moves in from these soffit vents in a way that is similar to the stack effect. It goes out through the vents in your attic, thereby creating a passage for natural ventilation that will save you money. If you do not have soffit vents, you will discover that it is very economical to have them installed or to install them yourself.
You may be asking what this has to do with air leakage. In an earlier blog, I talked about finding air leaks in your home using your central air and heating unit? I hope that that procedure helped you to find some of those leaks. In the same way that your air unit draws air in from your interior rooms and exterior cracks in your doors and windows, the stack effect will pull air through the same placesâ€”even when your unit is not running.
I hope I have helped you to understand a bit more about how your home works. Your home needs to perform at its highest potential to help you save money and become “greener.” And you can help it do that! Talk to your local HVAC contractor, and ask him about the stack effect. I feel certain that he will be able to explain this to you. He will also be able to show you ways of minimizing this effect in your home to help it become more energy efficient and save you money.