The most recent blogs at Green Building Advisor

How I Fixed My Leaky, Underinsulated Exterior Wall

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

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.

Siding and Soffits at the Blue Heron EcoHaus

Posted on June 14, 2016 by Kent Earle in Guest Blogs

Editor's note: Kent Earle and his wife, Darcie, write a blog called Blue Heron EcoHaus, documenting their journey “from urbanites to ruralites” and the construction of a superinsulated house on the Canadian prairies. Their previous blog on GBAGreenBuildingAdvisor.com was called Placing the Concrete Floors. The blog below was originally published in August 2015. (A complete list of Kent Earle's GBA blogs is provided in the “Related articles” sidebar below.)

Reducing Concrete’s Hefty Carbon Footprint

Posted on June 13, 2016 by Nate Berg in Guest Blogs

A roomful of materials scientists, gathered at UCLA for a recent conference on “grand challenges in construction materials,” slowly passed a brick-size white block around the room. They held in their hands, briefly, part of the solution to one of those grand challenges. The white block, rock solid and surprisingly lightweight, was a new alternative to cement, the glue that holds together aggregate, or crushed rock, to make the world’s most ubiquitous building material: concrete.

Nailbase Panels for Walls

Posted on June 10, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

These days, lots of builders are installing a continuous layer of rigid foam on the exterior side of their wall 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. . The usual approach is to sheathe the wall with OSB or plywood, and then to install one or more layers of rigid foam outboard of the sheathing.

Some builders are beginning to simplify this process by switching to nailbase panels — rigid foam panels with a layer of OSB or plywood glued to one side. Since nailbase panels provide sheathing and foam insulation in a single panel, they should (in theory) simplify the construction process.

The Uneven Burden of Energy Costs

Posted on June 9, 2016 by Khalil Shahyd in Guest Blogs

A new study confirms that low-income households, households of color, multifamily households, and renting households spend a much larger percentage of their income on energy bills than the average family, providing new evidence of the urgent need to expand energy-efficiency programs to vulnerable communities.

Lingering Questions About PEX

Posted on June 8, 2016 by Emily Sohn in Guest Blogs

The calls and emails arrive as often as several times a week from people with concerns about drinking water. Some of the callers — who include homeowners, architects, and builders — want to know why their water smells like gasoline. Others want to know which kinds of pipes to install to minimize risks of exposure to hazardous chemicals.

Building an Off-Grid Home in Canada

Posted on June 7, 2016 by Craig Anderson in Guest Blogs

This is the first in a series of posts by Craig Anderson describing the off-the-grid house he built with his wife France-Pascale Ménard near Low, Québec. Craig writes about the "Seven Hills Project" in a blog called Sunshine Saved.

Solving a Roof Dilemma

Posted on June 6, 2016 by Scott Gibson in Q&A Spotlight

Joe B is building what he hopes will be a 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.-certified home in Port Washington, New York, a town on the north shore of Long Island in Climate Zone 4. The house is well underway, but Joe worries about the potential for trouble in a very complex roof design.

Thermal Drift of Polyiso and XPS

Posted on June 3, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Most insulation materials have an R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. lower than R-5.6 per inch. As David Yarbrough, a nationally known insulation expert, explains, “At 75°F, the theoretical maximum R-value of a product is 5.6 per inch. That represents the maximum R-value if there is no convection and no radiation — it represents the pure conductivity of air. That’s as high as you can go unless you are talking about a product that incorporates encapsulated gas, or a vacuum, or nano-scale powders.”

Should We Promote Heat Pumps to Save Energy?

Posted on June 2, 2016 by Steven Nadel in Guest Blogs

Heat pumps are going through a period of innovation. Ductless heat pumps are more available; cold climate heat pumps have been developed; higher minimum efficiency standards for heat pumps have been established by the U.S. government; and gas-fired heat pumps have been developed.

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