Building Science

Does the Nest Thermostat Save Energy?

Posted on May 20, 2015 by Allison A. Bailes III, PhD, GBA Advisor

The Nest Learning Thermostat has been on the market for nearly four years now. One of the biggest things the Nest folks use as a selling point is energy savings. "Programs itself. Then pays for itself." That's the first thing you see when you go to the Nest homepage. But what do the data say? Three independent studies plus a white paper from Nest provide some answers. ( first reported on these three studies in a February 2015 news story.)

Nest Thermostat Data Revealed for First Time

Posted on May 13, 2015 by Allison A. Bailes III, PhD, GBA Advisor

The Nest thermostat has been around since October 2011, quietly collecting data on how your home — and the homes of hundreds of thousands of your neighbors — operates. It gathers information about indoor temperature, relative humidity, air conditioner runtime, auxiliary heat operation for heat pumps, and much more. Unlike the Ecobee thermostat, however, Nest doesn't let its owners see all those data (which is a problem only for energy geeks really). Enter Michael Blasnik.

The Physics of Water in Porous Materials

Posted on May 6, 2015 by Allison A. Bailes III, PhD, GBA Advisor

I like to tell people I'm a recovering academic. The truth is, though, that I haven't left physics behind. That would be impossible since I've been making a career in the world of building science. So today I'm going to delve into that subset of building science called building physics as we take a look at the physics of water in porous materials. You'll also learn about the fourth state of water, the one that's not liquid, not solid, and not vapor.

Lstiburek’s Ideal Double-Stud Wall Design

Posted on April 29, 2015 by Allison A. Bailes III, PhD, GBA Advisor

Joe Lstiburek called me last week to set the record straight. I had written an article about a study of moisture in double-stud walls in a Massachusetts home, and his company, Building Science Corporation (BSC), had done the research as part of the Building America program. They found elevated moisture content in the cold, exterior sheathing, and Joe wanted to make sure everyone knew, "I would never build that wall because I consider it too risky."

Is Cold Sheathing in Double-Wall Construction at Risk?

Posted on April 22, 2015 by Allison A. Bailes III, PhD, GBA Advisor

Insulation is good. More insulation is better (although at some point, more may not be cost-effective). It reduces the amount of heat a home loses in winter or gains in summer.

An Interview with Building Science Pioneer Terry Brennan

Posted on April 15, 2015 by Allison A. Bailes III, PhD, GBA Advisor

Last week I got a chance to sit down and talk with Terry Brennan in Dallas at the Air Barrier Association of America’s annual conference. He may not be as famous as Joe Lstiburek, but he’s every bit the building science pioneer. Armed with a physics degree, the ASHRAEAmerican Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). International organization dedicated to the advancement of heating, ventilation, air conditioning, and refrigeration through research, standards writing, publishing, and continuing education. Membership is open to anyone in the HVAC&R field; the organization has about 50,000 members. Handbook of Fundamentals, and a desire to reduce the environmental impact of buildings, he built houses and wrote energy modeling computer programs back in the 1970s and ‘80s.

Should the DOE Increase Furnace Efficiency Standards?

Posted on April 8, 2015 by Allison A. Bailes III, PhD, GBA Advisor

Do you know when the U.S. last raised furnace efficiency standards? It was 1987. Do you know how long the U.S. Department of Energy (DOEUnited States Department of Energy.) has been trying to change that? At least since 2007.

The past eight years have been a sad case of industry heavyweights preventing progress on this important issue. The DOE, however, just proposed a new rule, so we might finally see some action here. Do you know when it's set to go into effect, if passed?

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.

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