Building Science

How to Get Your Ducts Inside the Building Enclosure

Posted on December 4, 2013 by Allison A. Bailes III, PhD, GBA Advisor

I'm a big advocate of getting ducts inside the building enclosure. In cooling climates, getting ducts out of an unconditioned attic can save you 15% on your electricity bills. It can reduce the size of air conditioner you need by 25%. If it's not in such a harsh environment, your air conditioner will last longer, too.

The History of Peeling Paint, Insulation, and Vapor Barriers

Posted on November 27, 2013 by Allison A. Bailes III, PhD, GBA Advisor

Back in the 1930s, a rash of paint-peeling showed up across North America. One thing that most of these homes had in common was insulation in the walls. Painters put two and two together and decided that the problem was the insulation. According to building scientist Bill Rose, the painters surmised that the problem was happening because insulation “draws water,” and some refused to paint insulated houses.

The 2015 IECC Recognizes Home Energy Ratings

Posted on November 20, 2013 by Allison A. Bailes III, PhD, GBA Advisor

Great news, everyone! (If you read that in the voice of Professor Hubert Farnsworth, please don't let your imagination run away with you. This really is great news.) The HERS Index will part of the 2015 International Energy Conservation Code. Why does that matter?

Because it will help home builders build better homes.

Spray Foam Insulation Is Not a Cure-All

Posted on November 13, 2013 by Allison A. Bailes III, PhD, GBA Advisor

Spray foam insulation is a great product. Homes insulated with it can be some of the most efficient and comfortable homes built. I've been in plenty of homes insulated with spray foam and can tell you that, when done well, those homes are airtight and comfortable. I’ve also seen homes where the spray foam was a waste of money.

Will the Energy Star Homes Program Survive Version 3?

Posted on November 6, 2013 by Allison A. Bailes III, PhD, GBA Advisor

Back in 2009, I attended a webinar given by Sam Rashkin, head of the Energy StarLabeling system sponsored by the Environmental Protection Agency and the US Department of Energy for labeling the most energy-efficient products on the market; applies to a wide range of products, from computers and office equipment to refrigerators and air conditioners. new homes program at the time. (He has since left the EPA for the DOEUnited States Department of Energy..) He explained the changes coming in the program as they prepared for the transition from what we now call Version 2 to the new Version 3.

A Brief Introduction to WUFI, in 5 Easy Pieces

Posted on October 30, 2013 by Allison A. Bailes III, PhD, GBA Advisor

If you have any involvement with the world of building science, you may have heard about something called WUFI and wondered what the heck it is. Maybe you've heard that it's a piece of software (several pieces, actually) that does hygrothermalA term used to characterize the temperature (thermal) and moisture (hygro) conditions particularly with respect to climate, both indoors and out. modeling. Well, today's your lucky day because I recently went through a two-day class on WUFI 1-D with Dr. Achilles Karagiozis and Mr. Mikael Salonvaara of Owens Corning, and I'll give you a brief explanation of what it's all about.

The Ventilation Omission That Can Make You Sweat

Posted on October 23, 2013 by Allison A. Bailes III, PhD, GBA Advisor

If you're designing a ventilation system, first you have to determine how much outdoor air the house needs. You can use the ASHRAE 62.2A standard for residential mechanical ventilation systems established by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers. Among other requirements, the standard requires a home to have a mechanical ventilation system capable of ventilating at a rate of 1 cfm for every 100 square feet of occupiable space plus 7.5 cfm per occupant. standard or the new BSC-01 standard for that task. Then you have to decide what type of ventilation system to use: positive pressure, negative pressure, or balanced. In many green homes, the balanced system is becoming a popular choice.

The Lipstick-on-a-Pig Million-Dollar Home Syndrome

Posted on October 16, 2013 by Allison A. Bailes III, PhD, GBA Advisor

I wonder about a lot of things. I wonder what life would be like if gravity were stronger. I wonder why Americans don't dance more. I wonder why so many people who can afford million-dollar homes get cheapo HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. systems. That last one bugs me more more than the first two, by the way. It weighs on my mind because cheapo HVAC seems so out of step with the rest of a million-dollar home.

When You’re Financing a Green Home, Payback Is Irrelevant

Posted on October 9, 2013 by Allison A. Bailes III, PhD, GBA Advisor

If you're buying a green home or investing in energy efficiency improvements for your existing home, calculating the simple payback for your investment is at best incomplete and at worst, completely irrelevant. Before I get to the reasons why payback isn't the right way to look at home energy efficiency improvements, let's define simple payback.

Five Ways to Deal with Crawl Space Air

Posted on October 2, 2013 by Allison A. Bailes III, PhD, GBA Advisor

If you have a home with a crawl space — or are building or buying one — you have several options on what to do with that particular foundation type. Most crawl spaces are vented to the outdoors, but over the past decade, encapsulating the crawl space (as shown in the photo here) has gained favor among builders of green and energy efficient homes. It's often seen as the best way to eliminate the moisture problems that often result from vented crawl spaces. But what do you do about the air down there?

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