Building Science

Seven Reasons to Gut Your Aging Bathroom

Posted on August 24, 2016 by Allison A. Bailes III, PhD, GBA Advisor

If your home is old enough for a bathroom renovation, you may want to go ahead and completely gut it. I remodeled my bathroom this year and began with a complete demolition. If I hadn't, a number of problems would have been unavailable for repair... or even undiscovered.

Here's what I found when I opened up the walls and ceiling of my 1970 condo in the Atlanta, Georgia area.

Three Reasons to Remove Attic Floor Insulation in a Sealed Attic

Posted on August 10, 2016 by Allison A. Bailes III, PhD, GBA Advisor

I get asked a lot of questions about spray foam. Do I need an ignition barrier? Should I use open-cell or closed-cell spray foam? Will open-cell spray foam really rot my roof?

But the question I get more than any other on this topic is about whether or not the insulation on the attic floor should be removed when insulating the roof deck in an existing home. As you can tell from the title of this article, my answer is to remove it. Here are my three reasons, in increasing order of importance.

Why North America Needs Its Own Passive House Standard

Posted on August 3, 2016 by Allison A. Bailes III, PhD, GBA Advisor

There's this thing called passive houseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates.. It's a terrible name. Almost everyone agrees on that. Look at how its adherents are driven to a frenzy and you'll see that the name doesn't really fit. The houses themselves aren't passive either, but let's leave that aside for now.

The RESNET Standard Becomes the New Ventilation Battleground

Posted on July 27, 2016 by Allison A. Bailes III, PhD, GBA Advisor

Just because I haven't written about the jockeying over ventilation rates and strategies with 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. committee doesn't mean nothing's going on. If you've been following the battle over this issue, you know that Joe Lstiburek, PhD, PE, got fed up with 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. and introduced his own ventilation "standard" in 2013. Then the "Great Ventilation Debate" happened in Detroit, and he got back on the ASHRAE 62.2 committee.

Stuff happened and now RESNET just put an interesting amendment out for public comment. Follow that?

From Superinsulation to Passive House, With a Trip Across the Pond

Posted on July 13, 2016 by Allison A. Bailes III, PhD, GBA Advisor

In 2002, Katrin Klingenberg introduced the PassivhausA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. program to North America when she built the Smith House in Urbana, Illinois. She had come to the U.S. from Germany, where she studied architecture and got involved with Passivhaus. But is this really where it all began?

Complex Three-Dimensional Air Flow Networks

Posted on June 29, 2016 by Allison A. Bailes III, PhD, GBA Advisor

A lot of discoveries and research work over the past four decades have ledLight-emitting diode. Illumination technology that produces light by running electrical current through a semiconductor diode. LED lamps are much longer lasting and much more energy efficient than incandescent lamps; unlike fluorescent lamps, LED lamps do not contain mercury and can be readily dimmed. to our current understanding of air leakage in buildings. I’ll mention a few here, but I want to focus on one: the MAD AIR paper by John Tooley and Neil Moyer. The full title of the paper was, Mechanical Air Distribution And Interacting Relationships. The first letters of those words spell out MAD AIR.

How I Fixed My Leaky, Underinsulated Exterior Wall

Posted on June 15, 2016 by Allison A. Bailes III, PhD, GBA Advisor

When I began remodeling my master bathroom last month, I found the exterior wall ripe for some serious improvement. It had a number of problems, and I was excited to find them.

It was worse than I imagined in some ways. The photo at right shows the wall partially opened up.

Air Flow Pathways in a Leaky Exterior Wall

Posted on June 1, 2016 by Allison A. Bailes III, PhD, GBA Advisor

This spring I spent a lot of hours in my bathroom. I was sick. Really. I was sick and tired of having an outdated bathroom that was falling apart. So when my wife hit the road one Monday in late April to drive across the country, I got out my wrecking bar. The lead photo shows what it looked like at the end of my first full day of demolition.

I opened up the plumbing wall first. Lots of fun stuff, there. But the real fun came when I opened up the exterior wall. The four termite-damaged studs were part of that fun, but something else was even better.

Five Types of R-Value

Posted on May 18, 2016 by Allison A. Bailes III, PhD, GBA Advisor

We talk about R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. all the time. "I've got an R-19 wall," or "Code requires R-38 in my ceiling." But what are those numbers? As it turns out, when we talk about R-value we usually give the R-value of the insulation material itself. That's the case with both of those statements above. But what's the real R-value of the wall or the ceiling? Insulation makes up only a part of each. There's also wood and drywall and sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. and claddingMaterials used on the roof and walls to enclose a house, providing protection against weather. and...

The Water Efficiency Rating Score (WERS)

Posted on May 4, 2016 by Allison A. Bailes III, PhD, GBA Advisor

The Green Builder Coalition has been working hard on their Water Efficiency Rating Score — the WERS — for homes. The inaugural WERS training happened in Santa Fe, New Mexico, in March. I was in that class, and I learned a lot.

The program has been in development for the past couple of years. Now it's ready for prime time.

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