The Latest from the Energy Vanguard Blog

A heat pump is an air conditioner with a reversing valve
Posted by Allison Bailes on March 29, 2019
So we've looked at a simple way to estimate the heat pump balance point.  If you also read the comments of that article, you should be aware that there's more to the actual balance point than what I wrote in the article.  Today, though, let's look at two factors that can affect the balance point....
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At the balance point, a heat pump can supply the same amount of heat as a house needs
Posted by Allison Bailes on March 26, 2019
As the outdoor temperature drops on a cold day, a home's heating load increases.  At the same time, decreasing temperature means less heat in the air for a heat pump to pump indoors.  And at one special temperature, the capacity of a heat pump equals the heating load in the house.  That temperature...
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The 2019 Home Performance Coalition national conference is in Chicago. Be there!
Posted by Allison Bailes on February 22, 2019
My first conference after I officially left academia and got into the world of home performance and building science was in 2004.  Since then I've been to a whole lot of conferences.  There are even more building science conferences I could have gone to.  But fifteen years down the road now, I have...
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A heat pump pumping heat in winter
Posted by Allison Bailes on February 19, 2019
Since more people are using heat pumps these days, even in cold climates, let's spell out the three different types of heat that conventional heat pumps provide.  Why not!  We've just recently covered the three main sources of home heating and then stepped back and looked another group of three...
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Low indoor relative humidity in winter is common
Posted by Allison Bailes on February 15, 2019
I'm going to go out on a limb and make what you may think is an outrageous statement:  Water is the most interesting substance in the world.  Some of you may immediately respond, "Oh, yeah!  What about beer?"  (Or wine or Sidecars, Negronis, or Sazeracs or whatever your drink of choice is.) ...
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Abundant pressure drops in flex duct installation
Posted by Allison Bailes on February 8, 2019
"Don't sweat the small stuff," they say.  You know what, though?  That may be great advice for your emotional life but it's terrible advice for just about anything to do with buildings.  Whether you're designing them, specifying materials, putting them together, or fixing them later, buildings have...
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3 sources of heat in a Passive House or other high-performance home
Posted by Allison Bailes on January 31, 2019
Earlier this week I wrote about the three main sources of heat in homes.  At the end of the article I threw in a fourth one, solar energy, but then I dismissed it as something that people tried in the 1970s and '80s and have since abandoned for home heating.  And that's still mostly true, but my...
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3 main sources of home heating
Posted by Allison Bailes on January 28, 2019
It's wintertime in the Northern hemisphere and that means we're heating our homes.  The new year started off a bit on the warm side, with the temperature at nearly 70° F (21° C) here in the Atlanta area.  In terms of heating degree days (HDD), we've gone from about 12 HDD/day at the beginning of...
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What the heck is going on with this hotel room window?
Posted by Allison Bailes on January 22, 2019
The ASHRAE conference and AHR Expo were in Atlanta last week.  Because I live here, I didn't have to stay in a hotel but a lot of people I know came to town and did stay in hotels.  One of them, John Rockwell of ERV & HRV manufacturer Zehnder, sent me the photo above of the window in his room...
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A fogged up car windshield is easier to clear if you apply psychrometrics
Posted by Allison Bailes on January 18, 2019
A lot of people don't understand the best way to defog their car windshield in wet, cool weather.  About 30 years ago, I was on a group trip on a hired shuttle bus.  The outdoor temperature was probably in the 40s Fahrenheit and it was raining.  Perfect conditions for fogging up the interior glass...
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