... and the humidity. Here in central North Carolina the mercury hit the high eighties last week moving us from an often chilly spring into a warm early summer: time to fire up the A/C! What can we do to reduce the energy load from all that grateful cooling to save money and help the planet?
Turns out that in the humid summers of the southeastern US much of that energy is used not to cool the air but to wring the moisture out of it, and if our home continuously allows humid air to enter from the outside it’s like bailing a very leaky boat. Back in the energy crisis of the seventies air sealing meant caulking windows and air stripping doors. Now we know that our biggest air leaks in summer happen not through doors and windows but through our ceilings and floors because of the stack effect, where hot air rises, exits the building and and is replaced from below. Stack effect cooling can be a good thing if the replacement air from outside is cool and dry, but what if that replacement air entering the home is already hot and humid? That’s what's happening in the summer if you have an older home with a traditional ventilated crawl space, even when the windows and doors are tight shut. A multitude of small holes in the floor below and the ceilings above from electrical and plumbing penetrations allow an astonishing amount of unfiltered outside air to flow through your home, and your air conditioner is working overtime to cool and dehumidify that constantly changing air.
The good news is that there is something we can do about this which can pay for itself in short order with much-reduced summer energy costs, with a side benefit of better indoor air quality and mold control. It's called crawl space encapsulation, and I'll tell you all about it next time.