Building Science

Do you want a good air barrierBuilding assembly components that work as a system to restrict air flow through the building envelope. Air barriers may or may not act as a vapor barrier. The air barrier can be on the exterior, the interior of the assembly, or both. on your house? Of course you do. No one who knows anything at all about building science believes that old myth that a house needs to breathe. We want airtight houses, but then we want mechanical ventilation to bring in fresh air from outside (well, at least as fresh as you can get from your outside).

Amy Musser has a PhD in Architectural Engineering and, like me, used to be a college professor. Her husband, Matthew Vande, is an architect with an MS in Architectural Engineering. He is also a treehugger (see the black and white photo below). Together, they founded Vandemusser Design, a firm that provides green design, certification, and consulting.

One of the fundamental principles of building science is that buildings must be suited to their climate. When they're not, problems can ensue. Maybe it's just that they're not as efficient as they should be. Maybe it's worse.

Occasionally I get asked if it's OK to put the condensing unit of an air conditioner or heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump. in a garage or other room that's a buffer space. The thinking is that since the temperature may not be as hot in summer or as cold in winter, the system will operate more efficiently.

I saw recently that this same question came up in a column in Home Power magazine, so I thought this would be a good time to cover this issue (once and for all?) here.

Probably the biggest news I heard at the 2013 RESNET conference this year was that the Air Conditioning Contractors of America (ACCA) and 12 other organizations had asked the American National Standards Institute (ANSI) to have the Building Performance Institute's (BPI) accreditation as a Standards Development Organization (SDO) revoked. Really!

I just returned from Arizona, where I spoke at this year's conference of the Structural Insulated Panel Association. Since the conference was in Tucson, I also took the opportunity to visit with my friend David Butler of Optimal Building Systems.

Really, the argument about whether you should vent a crawl space in a humid climate is over. Advanced Energy's research project from 2002 proved that closed crawl spaces outperform vented crawl spaces.

A quick look at the psychrometric chart below shows that the argument should never have existed in the first place. (Click the image to see an enlarged version.)

I was a kid a long, long time ago. Seems like it was another century ... another millennium even. Wait a minute — it was another millennium!

That was back in the day when we used to ride bicycles without helmets, apply mercury to our wounds, move seat belts out of the way (if the car even had them), and put our tongue on steel poles in the middle of winter. Of course, in Texas and Louisiana we just ended up with a bad taste in our mouth from those steel poles and wondered why people made such a big deal about it.

Labradors? James Brown? What do either of those have to do with the RESNET conference?! Be patient, my friend. All will be revealed shortly. The 2013 conference sponsored by the Residential Energy Services Network (RESNET) in Orlando a few weeks ago was fantastic. It and Building Science Summer Camp are my two favorite events of the year, and this year RESNET was better than ever.

I've written a lot about duct problems (especially those in flex duct) because they're so abundant. A couple of years ago, I even wrote an article in the Energy Vanguard Blog about whether or not flex duct should be banned. My answer was no — but that we need better quality control.