Why you may want to think about air sealing your home, even if you’re not doing an all-out retrofit.
There’s little wonder why so many individuals and businesses are trying to increase the efficiency of their buildings–it saves money, saves resources, often adds to the value of the structure and, of course, it’s better for the environment. As awareness of our own environmental impact continues to expand, people are looking for more ways in which they can live sustainably.
Building structures, at least for the last several hundred years, hasn’t been particularly sustainable. In the era of cheap energy and global supply chains that ensured easy access to materials, being environmentally conscious was just not a part of building development, for most people anyway.
But that’s changing and homeowner, designers, builders and architects are increasingly focusing their projects around energy efficiency, low-impact building methods and materials, the longevity and durability of the structure and its affect on the immediate environment. But let’s say you’re not building from scratch. Let’s say you’re not even about to undertake a major retrofit. Are there relatively minimal things you can do to drastically and quickly improve the efficiency of your home (and your annual spending on energy)?
Yes!
And it probably won’t surprise you to learn that one of the most common steps you can take to increase energy efficiency is actually a cornerstone of passive house building: creating the proper air seal.
What is an air seal?
To understand the process, we need to understand our enemy: air leakage.
Air leakage, also called “infiltration” is air from outside that comes into the structure through unintended cracks or openings. Whether we’re dealing with new or old construction, the strategy is to reduce air leakage and encourage controlled ventilation.
The process of air sealing usually involves finding these leaky spots. With the help of a blower door, i.e. a giant sheet with an attached fan that sits over a large opening and rapidly pulls air out of the house, technicians can inspect the structure and find leaks. They typically do this with smoke pencils which reveal where air is leaking into the house, as the blower door is pushing it out.
Once leaks are found, depending on their location and size, there are many methods that can be used to seal them up. While many people reach out to professionals to carry out this work, it’s possible to undertake parts of this project on your own. Some people also have professionals conduct the audit, then choose to tackle the actual air sealing themselves. You can check out this handy guide from The Spruce for info on sealing different parts of the home: https://www.thespruce.com/air-seal-home-4174533
Cost and savings
So, why should you even do it. Well besides the environmental benefits, there’s the money. The U.S. government estimates that average American homes waste 30 percent or more of their annual energy usage due to air leaks. That’s money spent on heating and cooling that’s–literally–just disappearing into the air!
And it’s not all through holes in the roof or out-of-joint windows. Check out this cool graphic from Accurate Insulation that shows all the places where air may be escaping from your home. Older homes are particularly susceptible to leaks, which may be coming from the chimney, light fixtures, exterior vents, even the hole that your outdoor water spigot runs through. In fact, according to that same site, some of the biggest leaks are usually hidden from view, in the attic, crawl space or basement. (https://www.accurateinsulation.com/sealing/)
If you were to completely seal up your home, depending on the type and age of the structure, you could be looking at an annual savings of one-third on your heating and cooling costs.
For comparison, sealing the light fixtures in an average house usually costs between $100 and $200 while a full, professional air sealing service on a 2,500 sq. ft. home runs between $800 and $2,000. The average cost for an energy audit on a 1,200 sq. ft. home is $150. Your local market, type and size of structure, and which service you go with all determine the actual cost–these numbers are very general. But it’s possible to see an air sealing investment pay itself off within only a few months or, in the case of more extensive air sealing, a couple years. For example, take this case study conducted by Oak Ridge National Laboratory, which found that spray “foam sealants had a payback from 2 weeks to 9 months and a one-year ROI of 145%-2370%” and that, on average, “payback from spray foam sealant was 4 months with a… seven-year ROI of 4400%.” (https://web.ornl.gov/sci/buildings/conf-archive/2010%20B11%20papers/80_Bibee.pdf)
If you want to dig deeper into the numbers, check out this incredible, localized guide to air sealing from FIXR, which lets you enter your location for more accurate numbers and breaks down the costs for different types of sealants. (https://www.fixr.com/costs/air-leaks-sealing)
And if you’re thinking about doing some air sealing work yourself, here are tips directly from the Department of Energy:
(https://www.energy.gov/energysaver/weatherize/air-sealing-your-home)
• Test your home for air tightness.
• Caulk and weatherstrip doors and windows that leak air.
• Caulk and seal air leaks where plumbing, ducting, or electrical wiring comes through walls, floors, ceilings, and soffits over cabinets.
• Install foam gaskets behind outlet and switch plates on walls.
• Inspect dirty spots in your insulation for air leaks and mold. Seal leaks with low-expansion spray foam made for this purpose and install house flashing if needed.
• Look for dirty spots on your ceiling paint and carpet, which may indicate air leaks at interior wall/ceiling joints and wall/floor joists, and caulk them.
• Cover single-pane windows with storm windows or replace them with more efficient double-pane low- emissivity windows. See theWindows section for more information.
• Use foam sealant on larger gaps around windows, baseboards, and other places where air may leak out.
• Cover your kitchen exhaust fan to stop air leaks when not in use.
• Check your dryer vent to be sure it is not blocked. This will save energy and may prevent a fire.
• Replace door bottoms and thresholds with ones that have pliable sealing gaskets.
• Keep the fireplace flue damper tightly closed when not in use.
• Seal air leaks around fireplace chimneys, furnaces, and gas-fired water heater vents with fire-resistant materials such as sheet metal or sheetrock and furnace cement caulk.