Energy Vanguard Blog

Will Shading Your Air Conditioner Save You Money?

Posted by Allison Bailes on Mon, Jul 13, 2015

I got a question this weekend that's often asked—and, I'm sure, wondered about—by homeowners: "Will my household AC system run more efficiently (perhaps cycle on/off fewer times, or the compressor won't have to run as long when it cycles on) by shading the compressor?" I've written about the outdoor unit of air conditioners and heat pumps a few times, but I've never tackled this question directly. Let's change that now.

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Tags: heating & cooling

The Wonderful, Blunderful World of Construction

Posted by Allison Bailes on Fri, Jul 10, 2015

Jeffrey was driving through Atlanta the other day and saw a new building under construction that forced him to slam on the brakes. He got his camera out and took the photo below. Can you see why he was so excited?

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Tags: building enclosure, insulation

A Sticky Psychrometric Situation: Wet Bulb Temperature

Posted by Allison Bailes on Tue, Jul 7, 2015

Wet bulb temperature tells you how easy it is for water to evaporate. Sounds simple enough, right? Today I'll give you a couple of examples to see how well you really understand that simple statement. First, early last month my friend Mike MacFarland texted me about the day he wore his wet bulb shirt on a mountain bike ride. Here's what he said:

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Tags: comfort, environment & sustainability, moisture problems, health & safety

Could an Energy Code Really Be So Simple?

Posted by Allison Bailes on Fri, Jul 3, 2015

Energy codes have all kinds of requirements. You have to have certain R-values in walls, floors, and ceilings. Your windows have to have the right U-values and solar heat gain coefficients. The infiltration rate and duct leakage have to be measured and come in below a threshold for your climate zone. And then there are the different pathways for compliance: prescriptive, UA tradeoffs, performance, or HERS Index. But what if all you needed to do was to hit two numbers?

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Tags: energy code

OSHA Has New Rules for Working in Crawl Spaces and Attics

Posted by Allison Bailes on Thu, Jul 2, 2015

Who among us doesn't love spending time in crawl spaces and attics? I've certainly done my time there. A lot of my friends hang out there, too. I found out in an email from the Building Performance Institute (BPI), however, that the US Occupational Safety & Health Administration (OSHA) will have new requirements for companies who send their workers into areas defined as "confined spaces." This has the potential to bring some significant changes to the way home performance companies, weatherization contractors, and others in the construction industry do their jobs.

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Tags: crawl space, attic, health & safety

3 Cool Videos about Hydrophilic, Hydrophobic, & Hygroscopic Materials

Posted by Allison Bailes on Wed, Jul 1, 2015

As long as we're exploring the wonderful world of water, we ought to show some of the cool stuff it does. In my article Introduction to the Physics of Water in Porous Materials, I described hydrophilic, hydrophobic, and hygroscopic materials. Turns out they're pretty important to building science. Yesterday I saw a video of hydrophobic sand and that got me looking on Youtube for other good videos of this sort.

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Tags: fun, building science

Is Evaporative Cooling the Answer to High Air Conditioning Costs?

Posted by Allison Bailes on Tue, Jun 30, 2015

This time of year, air conditioners are running like mad to keep people cool in their homes. Here in Atlanta, we've had a couple of weeks of hot, muggy weather, with a little break on Sunday. Now we're heading back to the mid-90s with high dew points again. As a result, some people are starting to dread those air conditioning bills arriving and wondering what they can do to save energy. Is the Kickstarter-funded Mistbox the answer?

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Tags: scams & ripoffs, heating & cooling

17 Reasons I Love Working with Buildings

Posted by Allison Bailes on Mon, Jun 29, 2015

Yesterday I had lunch with Robert Bean and Eric Griffin at the ASHRAE conference here in Atlanta. As we talked about how we got into the field of building science, I began thinking of the reasons I love doing what I do. My background is physics, and I really enjoyed teaching it when I was in academia, but I didn't really fit in there. When I discovered building science (and later blogging), I finally found my niche. Here's why:

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Tags: fun, design, education, business, comfort, indoor air quality, environment & sustainability, big picture, creativity, health & safety, blogging

Psychrometrics, Part 2 - The Quantities in the Chart

Posted by Allison Bailes on Tue, Jun 2, 2015

Psychrometrics, you may recall, is the science that involves the properties of moist air and the processes in which the temperature or the water vapor content or both are changed. To understand how all that works, we need quantities and we need them to be well-defined. Some are easy to understand (e.g., dry bulb temperature and barometric pressure); others are a bit more abstract (e.g., enthalpy). Here we'll take a look at the main psychrometric quanitites, define them carefully, and tell which commonly used term you should avoid.

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Tags: moisture problems, ventilation, heating & cooling

How to Clean Out Your Air Conditioner's Condensate Line

Posted by Allison Bailes on Fri, May 29, 2015

Your air conditioner does two jobs: It cools down the air and it dehumidifies the air. If you live in a dry climate, you want the AC to dehumidify as little as possible because it uses extra energy and makes you spend more on lip balm and hand lotion. If you live in a humid climate, you really want it to do that second job as well as it can to keep your indoor air dry and comfortable. But where does all that condensate go?

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Tags: heating & cooling