The Latest from the Energy Vanguard Blog

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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Willis Carrier, inventor of the modern air conditioner
Posted by Allison Bailes on November 26, 2018
Happy birthday to Willis Carrier!  He invented modern air conditioning and changed the world.  In his quest for a device to control humidity in the Sackett-Wilhelms Lithographing & Publishing Company in Brooklyn, New York, he invented a device that changed migration patterns in the United...
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Aprilaire high-MERV filter with carbon
Posted by Allison Bailes on November 9, 2018
What is a hair's breadth?  A strand of the finest human hair is about 20 micrometers (also called microns) in diameter.  Take a piece and slice it in half.  Then take one of those halves and slice it in half again...and then one more time.  Now you've got a sliver of hair that's 2.5 microns wide. ...
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What's that noise I hear in there?
Posted by Allison Bailes on October 31, 2018
KERKLUNK! I instantly spring up in my bed at the loud noise.  "What the heck was that?!"  I don't know but it seemed to have come out of the heating vent on the wall above my dresser. I'd been lying quietly in bed on this chilly autumn night, half asleep yet still awake enough to know that was a...
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What happens to the air flow in ducts when the size changes?
Posted by Allison Bailes on October 29, 2018
As we continue our study of indoor air quality and filtration, we now come back to duct design.  Today's lesson is on an interesting bit of physics that applies to anything that flows.  It could be heat or particles or electromagnetic energy.  In our case, it's air, a fluid, and the physics we're...
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