Building Science

An Easy Retrofit for Return Air

Posted on October 18, 2017 by Allison A. Bailes III, PhD

Your bedroom really doesn't aspire to be a balloon. Yet, because of the way your heating and air conditioning system was installed, it may be acting like one. At least to an extent. It doesn't expand the way a balloon does, but it does get blown up.

Think about it. If your bedroom has a supply register from your HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. system but no return grille or other pathway for the air to make its way back to the unit, what happens to that air blowing into the room when you close the door?

Four Sources of Crawl Space Moisture

Posted on October 11, 2017 by Allison A. Bailes III, PhD

Here in the southeastern U.S., we have a lot of crawl spaces. Most are vented. Even most new ones are vented. It's not because it's the best way to keep them dry. That's certainly not true. We have enough research on crawl spaces to know better. No, they're vented because foundation vents got into the code decades ago and, once there, they’ve been difficult to dislodge.

So if you have a vented crawl space, especially in a humid climate, it most likely has moisture problems. And where does that moisture come from? Let's take a look.

The Difficulties of Third-Party HVAC Design

Posted on October 4, 2017 by Allison A. Bailes III, PhD

What if a builder refused to build from plans drawn by an architect? What if a tile installer refused to implement designs handed to them and instead did their own thing? What if an HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractor told a potential client they wouldn't install a system designed by a third party to ACCA protocols?

One of those questions is more real than the others. Of course builders build from architects' plans and tile installers don't throw out designs they're asked to implement. But third-party HVAC design is a different animal.

Pete’s Product Puzzle: VersaDry

Posted on September 21, 2017 by Peter Yost

I first “learned” about VersaDry when a colleague of mine here at BuildingGreen — our materials and product expert, Brent Ehrlich — sent me the photo reproduced at right. I was in the same boat you are right now: “OK, thanks for the photo, Brent, but what the hell is this VersaDry bent-metal thingamajig?”

He replied, “Oh, yeah, here is another photo that will help.” This time he sent me the photo reproduced as Image #2, below.

Thinking Clearly About the 3 Levels of the Building Enclosure

Posted on September 20, 2017 by Allison A. Bailes III, PhD

When you approach the subject of building science, especially regarding heat, air, and moisture flows through a building enclosure, it's easy to get confused. There's a lot to learn: blower door testing, insulation grading, R-value, vapor permeance, radiant barriers, combustion safety, solar heat gain coefficients, and on and on. That's why we break things down into simpler pieces.

Is It Possible to Get Condensation on a Sponge?

Posted on September 13, 2017 by Allison A. Bailes III, PhD

I recently taught a class called What the Duct!? at the Builders' Boot Camp in Virginia. Paul Francisco was one of the other instructors (teaching about indoor air quality), and on the last evening at dinner, our conversation turned to building science. (Imagine that!)

An Interesting Moisture Problem in a Trendy Restaurant

Posted on September 6, 2017 by Allison A. Bailes III, PhD

I've got the curse, you know. I can't walk into a building and not check out what's going on with ductwork, windows, and anything else that lets me apply what I know about building science.

Recently, I went to lunch at a trendy restaurant near Emory University and of course looked up at the ceiling. You can see what caught my attention in photo at right. The restaurant is only three or four years old, so I've been watching this problem get worse for a while now.

I have a few ideas about what's happening here. Do you?

SonicLQ: Reconnecting Acoustics and Airtightness

Posted on August 24, 2017 by Peter Yost

Back in the early days of airport noise mitigation programs, there was a pretty strong link between air leakage and sound. A document titled “Tips for Insulating Your Home Against Aircraft Noise” noted, “Sound travels from the exterior to the interior of the home in two ways: through solid structural elements and through the air…. Wherever air can infiltrate a home, sound can as well.”

The Truth About Al Gore’s Carbon Footprint

Posted on August 23, 2017 by Allison A. Bailes III, PhD

Al Gore is in the news again. His new climate change movie, An Inconvenient Sequel: Truth to Power, is in theaters now. And that means the folks who don't believe in climate change — or at least folks who don't believe that humans have any impact on it — are out in force trying to discredit the message.

As was the case 10 years ago when Gore’s original movie came out, they're going after his carbon footprintAmount of carbon dioxide and other greenhouse gases that a person, community, industry, or other entity contributes to the atmosphere through energy use, transportation, and other means. and making the case that he's a hypocrite. Let's take a look at the issues.

The Joy of Flex

Posted on August 16, 2017 by Allison A. Bailes III, PhD

I recently spoke at the Westford Symposium on Building Science. You may know it better as Building Science Summer Camp, since that's what everyone calls it. I'll fill you in on what you missed if you weren't there.

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