The Latest from the Energy Vanguard Blog

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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High-MERV filters are more restrictive but do they reduce air flow?
Posted by Allison Bailes on January 16, 2019
Over the past few months, I've taken a look at some critical issues for indoor air quality.  Starting with the issue of how much time we spend indoors, I then wrote about kitchen ventilation, the panoply of indoor air pollutants, problems with filters in general and with high-MERV filters.  Now let...
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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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A sparkly fire to ring in the new year of 2019
Posted by Allison Bailes on January 3, 2019
Welcome to another January, this time in the year 2019.  The month, of course, is named after the Roman god Janus, who has two faces, one looking backward, one forward.  Because, you know, to really know where you're going, you have to understand where you've been.  2019 may be a brand new year,...
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