The Latest from the Energy Vanguard Blog

Plastic pipes usually indicate a high efficiency furnace. But what key piece does this ignore?
Posted by Allison Bailes on April 17, 2017
You can tell how energy efficient a furnace is by its official efficiency rating, the Annual Fuel Utilization Efficiency (AFUE). It's a measure of how much of the heat originally in the fuel that's being burned is available for delivery to the home. The more heat that gets lost up the flue or...
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The HVAC design process begins with a load calculation.
Posted by Allison Bailes on March 7, 2017
Here's a little conundrum for you. To get the right amount of heating and cooling to each room in your home, you need a load calculation. Rules of thumb don't work. But if you do a load calculation, the result isn't the size of air conditioner, heat pump, furnace, or boiler you need. It's only the...
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A plastic film with amazing radiative cooling capacity
Posted by Allison Bailes on February 21, 2017
When it's hot out, we want cold. At night, we like to be able to turn on the lights. During the daytime, it can be hard to find the darkness. All these things — hot and cold, light and dark, day and night — can seem like opposites. Chinese philosophy suggests, however, that these opposing forces,...
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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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hvac-air-handler-filter-blocked.jpg
Posted by Allison Bailes on October 14, 2016
There's really no end to the fun stuff you find when looking at furnace & air conditioner filters. Here are a few of my favorites for this Fall Friday.
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air-handler-ducts-inside-conditioned-space-1-mechanical-closet.jpg
Posted by Allison Bailes on September 7, 2016
There's a ton of new construction and remodeling going on in Atlanta. On a lot near where I live, a developer tore down the old house and is building two new ones. This weekend, I took the opportunity to check out their progress on the first one and saw the mechanical system roughed in on the first...
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hvac-load-calculation-equipment-sizing-manual-e-contractor-mistakes.jpg
Posted by Allison Bailes on August 29, 2016
Air conditioner sizing rules of thumb must die. That's what I wrote in my last article. The most common rule of thumb is to use 500 square feet per ton to determine the size of air conditioner needed. Or 400 or 600 or some other number in that general vicinity. In my article, I showed a graph of...
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Posted by Allison Bailes on August 26, 2016
We design a lot of heating and air conditioning systems at Energy Vanguard. Alexander Bell, who goes by Andy, is our design wizard, and I've been getting involved with the process again lately. When I talk to potential clients, a lot of them tell me their contractor wants to size their air...
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filter-over-plenum-hole-ventilation-air-intake.jpg
Posted by Allison Bailes on August 5, 2016
I've seen some crazy things done to homes. It's usually someone's attempt to make things better. Sometimes that someone is a homeowner or other occupant. Sometimes it's a contractor. But it always seems to be a solution to a problem that creates other problems. It's just like they say: Our biggest...
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passive-house-wall-insulation-thickness.jpg
Posted by Allison Bailes on July 15, 2016
Passive house has a reputation for requiring ungodly amounts of insulation. It grew out of the superinsulation movement after all. If you're familiar with any passive house projects, you may be thinking about double-stud walls that are a foot thick or regular walls with 6 to 12 inches of rigid...
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