Building Science

How to Make Your Dumb Heat Pump Defrost Intelligent

Posted on March 5, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Heat pumps can get frosty when they run in heating mode. It doesn't happen all that often, but it's a fact of life when you're trying to extract heat from cold, outdoor air.

Do Combustion Safety Testing Protocols Need Fixing?

Posted on February 26, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Burning fuels inside a house can lead to serious health and safety problems. That's why energy auditors perform a variety of combustion safety tests to find potential hazards and recommend fixes.

A couple of weeks ago at the Dry Climate Forum, I heard Vi Rapp, PhD, from Lawrence Berkeley National Lab (LBNL) make an argument for changing the way we do combustion safety testing. It turns out that one of the tests we do may not be as helpful as many people think it is.

Should Home Builders Pay the Energy Bills?

Posted on February 19, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Three questions have been nagging at Rick Chitwood over the past 5 or 6 years. First, why is the HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. industry in California, where he lives and works, so pathetic?

Second, why have California’s strict energy standards, which have been in effect since 1978, not corrected the problem?

Third, how is it that he, who came to the HVAC business through a nontraditional route, has become a leader in the industry?

Understanding Air Barriers, Vapor Barriers, and Drainage Planes

Posted on February 12, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Is housewrap a vapor barrier? What's the purpose of building paperTypically referring to Grade D building paper, this product is an asphalt-impregnated kraft paper that looks a lot like a lightweight asphalt felt. The Grade D designation has come to mean that the building paper passes ASTM D779 (minimum 10-minute rating with the “boat test”) and different products are called out as “30-minute” or even “60-minute” based on D779 results. At times confused with roofing felt, roofing felts and building paper differ in two ways: felts are made of recycled-content paper, building papers of virgin paper; felts are made of a heavier stock paper; building papers a lighter stock. See also roofing felt.? Who'll stop the rain? I've covered this topic in various forms before, but the confusion about what the different building materials do is so widespread that I have to keep coming back to it.

I'm going to keep it simple here so maybe we can get a few more people to use the proper terms, and especially to know when not to use the term “vapor barrier” ... and when not to use it.

Green Buildings Aren’t Truly Green Without Location Efficiency

Posted on February 5, 2014 by Allison A. Bailes III, PhD, GBA Advisor

I was one of the lucky ones. I spent only two hours in my car when the big snowstorm of 2014 hit Atlanta on Tuesday. We got only about 2 inches of snow in my part of the city, but I made the mistake of going out for lunch at a restaurant right next to Emory University and the CDC compound. It took Jeffrey and me an hour and 45 minutes to drive the 2 miles back to the office. In the first photo below, you can see that the roads themselves were still in good shape at 2 o'clock, at least where we were.

Should Occupants Have Control of Their Home Ventilation System?

Posted on January 29, 2014 by Allison A. Bailes III, PhD, GBA Advisor

One of the points of contention in the great ventilation debate is whether a home's occupants should control their own ventilation systems.

Will a Gas Furnace Dry Out a Home’s Air?

Posted on January 22, 2014 by Allison A. Bailes III, PhD, GBA Advisor

I get asked from time to time if a gas furnace dries out the air in a home and makes a humidifier necessary.

Use Plenum Trusses To Keep Ducts Out of Your Attic

Posted on January 15, 2014 by Allison A. Bailes III, PhD, GBA Advisor

If you want to do something really stupid with the ducts for a heating and air conditioning system, put them in an unconditioned attic.

153 Green Building Acronyms and Initials

Posted on January 8, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Acronyms and initials (let's call that AI, for short, not to be confused with the other AI, which stands for artificial intelligence, or AIA, which stands for American Institute of Architects) are part of the jargon of every field. Our field, whether you call it building science, green building, home performance, or something else, is no exception.

What Is Heat?

Posted on December 25, 2013 by Allison A. Bailes III, PhD, GBA Advisor

While you slept last night, Santa Claus was putting his knowledge of physics to work. No, not with that silly anti-gravity stuff. Everyone knows the whole reindeer thing is just a cover for the way he really gets to all those houses in just one night. He uses one of the original Time Turners. In fact, Professor McGonagall got her first Time Turner from Santa himself.

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