Indoor Air Quality, Spring 2008:
Controlled Ventilation Starts with the Framing

 
Source: Sealing Air Leaks, U.S. Department of Energy Office of Energy Efficiency and Renewable Energy (EERE)
 
National data shows that 20-30% of a home's energy usage is lost through air infiltration. What does this have to do with Indoor Air Quality? Well, air leaks provide "random" ventilation, from random places, in random amounts, at random times and of random quality. As we discussed in "Healthy Indoor Air - Green Building Materials Aren't Enough", CONTROLLED ventilation is the preferred method of ensuring indoor air quality. In fact, it is the ONLY way to ensure good indoor air quality - relying upon random ventilation is gambling with your indoor air quality. The July 2007 article details options for providing controlled ventilation, but one thing is common to all techniques - random ventilation must be minimized for controlled ventilation to occur (this happens to save a good deal of energy too.)

What is the source of this random ventilation? The chart at the right shows that nearly half of all air leaks are from "Floors, walls and ceiling" (31%) and "Plumbing penetrations" (13%) combined. Much of this leakage is due to leaks in and around the framing, particularly between floors and the bottoms of walls and through penetrations in the framing for plumbing and electrical. In fact, despite all our talk about window weatherstripping in "Vintage Green Windows - Just Add Weatherstripping," above leaks around windows account for only about 10% of air leakage.

The good news is that it's EXTREMELY EASY to address this issue during the construction process. Cans of spray foam, caulk, and careful attention can all but eliminate the leaks. In an existing house that isn't being gutted and remodeled, it's trickier, but still relatively easy and inexpensive to make HUGE improvements.

We'll discuss this topic in detail in upcoming issues, in the meantime, here's more information:

We are sorry if we appear the bearer of bad news, but we want to be "the bearer of important news." The good news is that many of these problems have accessible, affordable and pleasant solutions. Please stay tuned...

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