The Latest from the Energy Vanguard Blog

The soffits, fascias, and gutters need to be replaced, opening up an air-sealing opportunity
Posted by Allison Bailes on November 11, 2019
The number one thing you need to do to protect a building is control water.  As the Canadian building scientist Gus Handegord said, "The three biggest problems in buildings are water, water, and water."  So, with the 1961 house I bought this year, one of the first things I discovered was the...
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Spray foam insulation in an encapsulated attic.  How good is at the eaves?
Posted by Allison Bailes on November 8, 2019
An attic that's brought inside the building enclosure is a beautiful thing.  This is most often done with spray polyurethane foam (SPF) insulation, either open-cell or closed-cell.  Here in the southeastern US, open-cell is most often the spray foam of choice.  But how well does this process of...
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Do convective loops in loose-fill fiberglass attic insulation cause it to lose up to half its R-value?
Posted by Allison Bailes on January 7, 2019
When you get into the world of building science, it's inevitable that you'll hear about the study that proved fiberglass insulation loses half its R-value because of convection within the insulation.  Or it could be you're a homeowner who's been told about this problem by an insulation contractor...
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Staying cool with air conditioning
Posted by Allison Bailes on June 11, 2018
It's getting hot out there. Here in the Southeast, we love our air conditioning.  In fact, without air conditioning, far fewer people would live in places like Houston, Hattiesburg, and Sopchoppy.  And that's true for the hot, dry places, too, like Phoenix, El Paso, and Boron. So if we're going to...
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loaa 2 insulation blown cellulose complete coverage energy vanguard
Posted by Allison Bailes on February 27, 2018
I love insulation. It's a wonderful thing because it saves energy. It makes buildings more comfortable. And it's pretty inexpensive considering how long it lasts (or should last). I get asked a lot for my opinion on the best insulation to put in a building and my answer is straightforward: A well-...
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Insulation on flex duct (Photo by Mike MacFarland, used with permission)
Posted by Allison Bailes on February 13, 2018
If you know a little building science, you've no doubt seen a lot of problems that occur with air distribution systems. Ducts just don't get anywhere near the attention they deserve in most homes, partly because they're hidden from view. I've written about ducts quite a bit here and have shown...
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raised heel truss, photo by APA - The Engineered Wood Association
Posted by Allison Bailes on August 7, 2017
A comfortable, energy efficient home begins with a good building enclosure. That means control layers. You've got to control the flows of moisture, air, and heat. Today, let's talk about controlling heat and further, let's focus on heat going through the top of the house. If you've read my Flat or...
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Condensation on the insulation jacket of a duct running through a crawl space
Posted by Allison Bailes on February 14, 2017
Water vapor from the air condenses on air conditioning ducts in humid climates. It's as normal as poorly insulated bonus rooms making occupants uncomfortable or cigarettes causing lung cancer†. Condensation on ducts is most common in crawl spaces and basements, where the air is more likely to have...
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humidifier-indoor-humidity-mold.jpg
Posted by Allison Bailes on November 14, 2016
It's that time of year when heating systems start coming out of their summer hibernation. (Except maybe in Vermont. Michael Blasnik's Nest data showed that Vermonters are about the last to start heating their homes in Fall.) Then everyone starts looking for their lotion and lip balm. Gaps appear in...
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spray-foam-insulation-attic-humidity.jpg
Posted by Allison Bailes on October 26, 2016
Three weeks ago, I wrote about an attic with spray foam insulation and the interesting humidity pattern we observed in it. We placed data loggers near the ridge and floor of the attic as well as in the living space and outdoors. In that last article, I showed the dew point data for the four...
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