Building Science

Beware of This Expensive Ventilation Scam

Posted on June 18, 2014 by Allison A. Bailes III, PhD, GBA Advisor

How much does an exhaust fan cost? Search online and you can find lots of them that move 200 cubic feet per minute (cfm) for $100 to $150. But, if you put one in a semi-attractive (emphasis on the "semi") package, create some fancy marketing materials, and target people who don't know much building science, you can charge $1,200 to $1,700 for that same fan. At least that seems to be the business plan for these three companies.

The Two Main Reasons Your Ducts Don’t Move Enough Air

Posted on June 11, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Two things. Just two things in your ducts are responsible for giving the blower in your furnace or air handler a hard time. They make the blower push against more pressure, thus reducing air flow or increasing energy use, depending on blower type. They cut the amount of air that gets delivered to the rooms. And they can be reduced but not eliminated. Do you know what they are?

The Top Two Reasons Powered Attic Ventilators Are a Waste of Money

Posted on June 4, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Three years ago I wrote an article titled, Don’t Let Your Attic Suck: Power Attic Ventilators Are a Bad Idea. Nearly a hundred thousand page views and 93 comments later, it's still generating lots of heat. I don't know why so many people are so defensive about powered attic ventilators (PAVs), but here are a few of the things they've said to me in the comments:

This Heat Pump Problem Is a Surprisingly Common Cause for High Electricity Bills

Posted on May 28, 2014 by Allison A. Bailes III, PhD, GBA Advisor

She lives in a small, simple house in southern Mississippi. It's only 1,700 square feet. Why then, she wondered, were her summer electricity bills running more than $600?

The house didn't have any energy-hog features like a swimming pool, and she didn't do stupid things like leave all the doors and windows open while she ran the air conditioner. What could it be?

California Study Shows Big Savings in Home Energy Retrofits

Posted on May 21, 2014 by Allison A. Bailes III, PhD, GBA Advisor

At the Forum on Dry Climate Home Performance earlier this year, I got to hear three building science experts talk about a really cool research project they've been working on in Stockton, California. Bruce Wilcox, John Proctor, and Rick Chitwood (Wilcox and Proctor are shown in photo at right) filled us in on the Stockton project, which now has two years of data and shows some really impressive results.

How to Buy an Energy-Efficient Ceiling Fan

Posted on May 14, 2014 by Allison A. Bailes III, PhD, GBA Advisor

A little over a decade ago when I was building a house and buying a bunch of ceiling fans, it wasn't so easy to figure out which fans were energy efficient and which weren't. That's not the case anymore because every ceiling fan now has a label on the package that tells you how much air movement you can expect for each watt of electricity you put into the fan.

The Great Ventilation Debate, Live at the ACI Conference

Posted on May 6, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Last week at the Affordable Comfort Conference (also known as ACI), I co-moderated a panel called The Great Ventilation Standard Debate.1 Duncan Prahl of Ibacos proposed the session and rounded up a collection of some of best building science folks in North America to be on the panel.

What Happens When You Put a Plastic Vapor Barrier in Your Wall?

Posted on April 30, 2014 by Allison A. Bailes III, PhD, GBA Advisor

A lot of people have heard advice about vapor barriers and vapor retarders. Many of them have walked away confused. A big part of the problem, I think, is that they've been told what to do — "Put it on the warm-in-winter side," or "Never use one" — but they haven't had the physics of what happens explained to them.

Does Open-Cell Spray Foam Really Rot Roofs?

Posted on April 23, 2014 by Allison A. Bailes III, PhD, GBA Advisor

Murmurs and hearsay about open-cell spray foam insulation have been gaining traction for a while. It rots roofs, people have told me. Not long ago, someone even told me that in Florida, roofing companies won't let their workers go up on roofs with open-cell spray foam because the roofs are so spongy, the guys fall right through.

Open-cell spray foam is getting a bad reputation among some people in the construction industry. But is it deserved?

How to Detect an Internet Solar Energy Scam

Posted on April 16, 2014 by Allison A. Bailes III, PhD, GBA Advisor

All I was trying to do was find some sports scores on Yahoo the other day when I saw it. I don't go looking for this stuff, and when I do see it, I try to ignore it. But this one clotheslined me with an unfair term.

That's the ad in question to the right. Have you seen it? I probably shouldn't tell you the name of the website (powerfreedom.com), but the kryptonite term that made my fingers go apoplectic was “free energy.” Seeing it capitalized intensified the effect. And the photo! Is that a diseased wireless router robot surrendering its secrets to me?

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