In the old days, we were taught buildings had to breath. We were wrong.
Buildings that breath have uncontrolled air movement. They're leaky. On cold, blustery days, when it's raining sideways and your furnace works overtime, unconditioned air is being forced into your home and you feel uncomfortable from drafts blowing across your body. On cold, still days, your furnace again works overtime as warm conditioned air leaks to the cold exterior, and you may again feel drafts. On hot, calm days, warm air will leak inside putting your air conditioner to the test. In a leaky home, winter or summer, you're wasting energy and undermining your comfort. Comfort shouldn't be a luxury.
Wasted energy and an uncomfortable environment are bad enough, but when we analyze the source of building envelope leakage, we face a number of challenges. Leaky windows, doors, and other wall penetrations are fairly easy to identify, but during construction, and often after, your home is punctured with hundreds of hidden holes. No matter where these holes are located, they allow uncontrolled air movement between your home and the outside. That means air from nasty attics, crawlspaces, and interior wall cavities can be pulled into your home as easily as fresh outdoor air. That could mean dust, insulation fibers, moisture, pest droppings, and all sorts of undesirable contaminants can undermine your indoor air quality, and potentially the health and safety of the occupants.
We've learned that one step in making homes more energy efficient, while improving indoor air quality, is to make them tighter. Hand in hand with that goal is to also provide adequate ventilation. These goals are not addressed separately, but as one.
As part of our holistic approach to Home Performance and improved resource efficiency, we use a Blower Door to estimate the amount of your home's envelope air leakage. A Blower Door is a diagnostic tool designed to measure the airtightness of buildings and to help locate air leakage sites. It consists of a calibrated fan for measuring an airflow rate, and a pressure-sensing device to measure the air pressure created by the fan flow. The combination of pressure and fan flow
measurements are used to determine the building airtightness. The
airtightness of a building is useful knowledge when trying to increase energy efficiency, improve Indoor Air Quality, or control building pressures.
The information we get from this test will not only help us pinpoint the locations of leaks in your building, it will also help us estimate the cumulative size of these holes. We can then prioritize sealing measures to reduce infiltration and exfiltration. In addition, we can determine how much mechanical ventilation your home will require to provide the safe, healthy environment you deserve.
The Envelope Leakage Test
The average home in the US, when all envelope penetrations are added up, has a cumulative hole about the size of a Hoola-Hoop. As stated above, a large portion of those penetrations are into attics, wall cavities, and/or crawlspaces. Unconditioned air can be pulled into your home from areas containing dust, insulation fibers, rat feces, moisture, or who-knows what. Sealing those penetrations is essential to having a resource efficient, healthy environment that is effortlessly comfortable. Comfort shouldn't be a luxury. Nor should good Indoor Air Quality.
Here are a few examples of holes that undermine the health, safety, comfort, and durability of your home.
