Building Science

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.

Raised-Heel Trusses Make Better Enclosures

Posted on August 9, 2017 by Allison A. Bailes III, PhD

A comfortable, energy-efficient home begins with a good building enclosure. That means control layers. You've got to control the flows of moisture, air, and heat.

Using Total Effective Length in Duct Design

Posted on July 26, 2017 by Allison A. Bailes III, PhD

Today I’m going to explain an important concept in one of the most popular ways of doing duct design. I’ve been writing a series on duct design over at my blog and began with a look at the basic physics of air moving through ducts. The short version is that friction and turbulence in ducts results in pressure drops. Then in part 2 I covered available static pressure. The blower gives us a pressure rise.

Pete’s Puzzle: Mold on Painted Clapboards is Food for Thought

Posted on July 20, 2017 by Peter Yost

Whenever my wife starts a conversation with, “OK, Mr. Building Scientist,” I know I am in some kind of trouble. That proved to be the case one day when we were out hanging laundry on the south side of our house.

62 Things We Should Ban to Improve Home Building

Posted on July 12, 2017 by Allison A. Bailes III, PhD

Let's face it. The state of home building isn't good. Yes, we have building science and energy codes and green building programs out the wazoo. We have cool new products and home energy raters and even Joe Lstiburek. Despite all this, we still have wild ductopuses, holey air barriers, and insipid insulation installations.

And I've finally lost my patience. I think the only way to improve the state of home building in America is to ban these things.

Air Sealing the Ceiling Joists in an Attached Garage

Posted on June 28, 2017 by Allison A. Bailes III, PhD

The I-joists in the lead photo here run across the top of the wall between the dining room and the attached garage in this home under construction in the Atlanta area. In the old days, before anyone worried about air moving through those joist cavities, the builder didn’t bother to do anything beyond securing the joists.

You can see here, though, that the builder of this home knows a thing or two about air sealing because they've put blocking between the joists. But what do they do next?

Combining Sheathing With a WRB and Air Barrier

Posted on June 22, 2017 by Peter Yost

Full Disclosure: First, there are a lot of different ways to get continuous air and water control layers on the exterior of a building enclosure. You can use housewrap, taped-and-sealed rigid foam insulation, liquid-applied membrane, or either the Huber Zip or Georgia-Pacific ForceField system. Each approach has strengths and weaknesses.

Climate Change Is Just a Theory

Posted on June 14, 2017 by Allison A. Bailes III, PhD

So the United States has announced it's withdrawing from the Paris Accord, the international agreement with nonbinding measures to mitigate the effects of climate change. Now everyone's up in arms, speaking in exasperated tones about the travesty of this decision.

"But... but... the science," they say. Yeah, let's talk about science.

Is Compressed Fiberglass Insulation Really a Problem?

Posted on June 7, 2017 by Allison A. Bailes III, PhD

I've been guilty of perpetuating a myth. Not long ago I wrote an article in which I said installing insulation, "cavities [should be] filled completely with as little compression as possible." But is compression really such a bad thing? Here on GBAGreenBuildingAdvisor.com, commenter Dana Dorsett wrote, "Compression of batts is fine (resulting in a higher R/inch due to the higher density) as long as the cavity is completely filled.”

Heating Degree Days Drop Again in 2017

Posted on May 24, 2017 by Allison A. Bailes III, PhD

We've had some beautiful cool weather here in Atlanta this spring. It's about 50°F outdoors as I write this, one week into the month of May. The high yesterday was only about 70°F.

We're getting a few more heating degree days (HDDThe difference between the 24-hour average (daily) temperature and the base temperature for one year for each day that the average is below the base temperature. For heating degree days, the base is usually 65 degrees Fahrenheit. For example, if the average temperature for December 1, 2001 was 30 degrees Fahrenheit, then the number of heating degrees for that day was 35.) in the middle of May. (Heating degree days are really just another way at looking at temperature, which I explained in more detail in a look at the fundamentals of degree days.) We occasionally pick up some HDD even in July and August. But it's the winter HDD that matter for heating — and that give us a clue about the climate.

Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!

Syndicate content