Building Science

California’s Mistake Puts Spray Foam Insulation on the Bad List

Posted on April 1, 2015 by Allison A. Bailes III, PhD, GBA Advisor

Last summer I learned about the state of California's efforts to create more healthful buildings and working conditions. In 2008, they passed the California Green Chemistry Initiative with the intent of reducing state residents' exposure to toxic chemicals.

A Home Energy Rating Is an Asset Label

Posted on March 25, 2015 by Allison A. Bailes III, PhD, GBA Advisor

When I'm explaining home energy ratings and the HERS Index to people, I often get asked, "How accurate is a HERS rating? Will my energy bills really be close to what it says?" In the mind of the questioner, that's one question. To someone who understands what HERS ratings really measure, it's two separate questions. Let me explain.

A Beautiful Near-Net-Zero-Energy Home in Utah

Posted on March 18, 2015 by Allison A. Bailes III, PhD, GBA Advisor

It's the day after St. Patrick's Day, so let me tell you a wee bit about the O'Mearas. Kevin and Svetlana O'Meara live in a beautiful home in Utah that's oh-so-close to being a net-zero-energy home. After I wrote about how home building is like skiing two years ago, Kevin invited me out to see their home and this year I managed to to do so.

Can Atmospheric Combustion Work in a Spray-Foam-Insulated Attic?

Posted on March 11, 2015 by Allison A. Bailes III, PhD, GBA Advisor

A while back I wrote about the incompatibility of putting an atmospheric combustion furnace in a sealed attic. Most often the attic is sealed by installing spray foam insulation at the roofline, thus bringing the attic inside the building enclosure and turning it into conditioned spaceInsulated, air-sealed part of a building that is actively heated and/or cooled for occupant comfort. (directly or indirectly). The good news is that some installers understand this problem and seek to address it. The bad news is what a few of them do.

Is Modeling a Four-Letter Word?

Posted on March 4, 2015 by Allison A. Bailes III, PhD, GBA Advisor

Energy modeling has gotten a bad reputation in the home performance world. One conference I've attended has gone so far as to say that it's "outside the sandbox" of topics presenters can cover. They want to see data, not modeled results. And they have good reason for that.

The Fundamentals of Series and Parallel Heat Flow

Posted on February 25, 2015 by Allison A. Bailes III, PhD, GBA Advisor

We used to build houses without giving much thought to heat flow through the walls, ceilings, and floors. The main thing was to provide some resistance against wind and rain, and then we'd get a fire going to try to make the indoor temperatures bearable.

If you've ever lived in an old, uninsulated house, you know that method didn't work that well so later we started putting insulation into the cavities in building assemblies. Homes with insulated cavities are much more comfortable, but how exactly does heat flow through building assemblies? Turns out there are two ways.

Why Is the HERS Reference Home Based on an Outdated Energy Code?

Posted on February 18, 2015 by Allison A. Bailes III, PhD, GBA Advisor

The HERS Index is a number that gives you a measure of how energy-efficient a home is. We can debate how relevant that number is or how accurate is the energy model it's based on, but the fact is that it's being used.

New Mexico Develops Innovative Water Efficiency Rating Score

Posted on February 11, 2015 by Allison A. Bailes III, PhD, GBA Advisor

Energy usually gets top billing in the green building community. It has a huge impact on the environment. We sometimes pay a significant amount for it (although most of us don't pay enough to motivate serious change, but that's another story). We can do energy modeling and home energy ratings. Plus, it's just really interesting!

A Drainage Plane Time Bomb Defused

Posted on February 5, 2015 by Allison A. Bailes III, PhD, GBA Advisor

I don't think I can ever say it enough, but the building enclosure consists of several control layers and each one has its job. The primary control layer is the one that keeps liquid water out, and it can be a tricky business.

Take the case of this condo building (yes, it's in the community where I live). It's got several problems, so I went to bat for building science here.

A Plethora of Building Science Conferences

Posted on January 27, 2015 by Allison A. Bailes III, PhD, GBA Advisor

I love going to conferences. Since I changed my career in 2004, I've gone to building science, green building, and home performance conferences nearly every year. (I think I missed 2006, but I had a lot going on then.) Last year I went to eleven of them, but then I'm a bit unusual.

You certainly don't have to go to that many, but if you're a home builder, home performance contractor, or home energy pro, I do recommend going to one conference a year so you can keep up with the latest trends, talk to your peers, and maybe add some arrows to your quiver.

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