Winter: a good time for a home energy audit?
People sometimes ask me if there's a time of year that's best for getting a home energy audit. Really, anytime is a good time, and it depends on your goals. As I wrote in my last post, if you have home renovations planned or are considering a heat pump, starting with an energy audit is a great idea.
But more directly to the question: winter is actually a great time, maybe even the best time, to get a home energy audit in Montana, for at least one reason: it's easier to see where your house is "leaking" energy.
Montana, including the Bozeman/Livingston area where I mostly work, gets cold in the winter. That means heating is usually the biggest single home energy use. The efficiency of your furnace, boiler, or other heating system is a factor, but usually the biggest factor is what holds the heat inside the house -- insulation and other materials collectively called the building envelope. A good building envelope is relatively air-tight so that it stops heated air from leaking to the outside, and includes insulation that slows the natural conductance of heat, which wants to move from hot to cold.
One of the main purposes of a home energy audit is to find deficiencies in the building envelope so they can be fixed. A blower door is used to modestly depressurize the house and measure the overall air-tightness of the building envelope. A thermal camera shows which surfaces are hot and cold, which can tell you about air leaks and also about missing insulation in walls.
The cool thing about winter is how well the thermal camera works. Because it's warm inside and cold (often very cold) outside, there's a strong thermal contrast between where the building envelope is good and where it's bad, and therefore a strong visual contrast (on a spectrum from red to blue) with the thermal camera. When it's 70 degrees inside and 10 degrees outside, a wall cavity that's missing insulation, for example, will show up as a big blue patch.
The combination of thermal camera with blower door in the winter is even cooler. Because the blower door is depressurizing the house, it's pulling cold air into the warm space. That means that air leaks that wouldn't otherwise show up on the thermal camera, such as around light fixtures in the ceiling, register loud and clear.
Seeing things so vividly on the thermal camera can help you chase down the problem. In December I did an audit for a friend, and he said his hallway was often cold. I whipped out the thermal camera, and sure enough, there was something going on with one of the walls. I climbed into the attic and found that the wall was connected to an uninsulated part of the attic, in back of the fireplace. Air sealing and insulating this area was one of my main recommendations for this project.
During winter, it's also just easier to see and feel the problem areas. Ice damming and huge icicles are often a sign of lacking insulation -- the leaking heat is melting snow on the roof that then refreezes at the eaves. You can feel the cold in the drafty and low insulation areas, which can help with diagnosis as a well focus the discussion of your goals.
Of course, often the same things are true (in reverse) during the summer, when it's hot outside and cool inside. The thermal camera shows the air leaks and missing insulation as blotches of red, not blue, and you feel the areas of the house that get too hot. Even in spring and fall there's usually some decent thermal contrast, and there are other tools and techniques for tracking down leaks in the thermal envelope.
In winter we tend to slow down and not think about home improvement. But it's a great time for a home energy audit. A winter home energy audit can get you lined up to confidently tackle your home projects during the warmer months. Reach out to schedule an energy audit while it’s still cold!
