The most recent blogs at Green Building Advisor

Blue Heron EcoHaus: Adding it All Up, Part 2

Posted on August 31, 2016 by Kent Earle in Guest Blogs

In mid-November 2015, just before we moved into our new house, we were asked to be part of the 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. Days tour (a worldwide weekend of awareness of Passive House and energy-efficient building). Well, not “officially” — we were asked to be a part of the tour by the event organizer in Saskatchewan, who was the Passive House (PH) consultant on what should become the first certified PH in Saskatchewan. Even though we did not build a PH, we did follow the standards as closely as I could justify. From the beginning we were not pursuing certification.

Rust Belt Cities Go Green to Aid Urban Revival

Posted on August 30, 2016 by Anonymous in Guest Blogs


Depending on how you look at it, Gary, Indiana is facing either the greatest crisis in its 110-year history, or the greatest opportunity. The once-prosperous center of steel production has lost more than half its residents in the past 50 years. Just blocks from city hall, streets are so full of crumbling, burned-out houses and lush weeds that they more closely resemble the nuclear ghost town of Pripyat, near Chernobyl, than Chicago’s glitzy downtown an hour to the northwest. Air, water, and soil pollution are severe.

How to Insulate the Attic in a 1910 Remodel

Posted on August 29, 2016 by Scott Gibson in Q&A Spotlight

Tim Lange is taking on a major renovation of his 1910 home in North Dakota that will include a new roof, exterior spray-foam insulation, and new doors and windows. His quandary is what to do in the attic.

"I think I've got a good handle on the exterior insulation process — using window bucks to create an 'outie' style window is the current plan," Lange writes in a Q&A post at GBA. "The third floor and attic are where I need some help."

High Humidity in Unvented Conditioned Attics

Posted on August 26, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

If you convert your vented unconditioned attic to an unvented conditioned attic by installing open-cell spray foam on the underside of your roof 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. , you may be surprised to discover that your attic is now the most humid room in your house.

Why? We don't know. Although building scientists haven’t achieved a consensus on the answer, we do have enough information to paint a picture of what’s going on.

A Business Model for Net-Zero Energy Districts

Posted on August 25, 2016 by Anonymous in Guest Blogs


Seven Reasons to Gut Your Aging Bathroom

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

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.

Build Disaster-Proof Homes Before Storms Strike

Posted on August 23, 2016 by Anonymous in Guest Blogs


Off-Grid in Canada: Solar Was the Only Real Choice

Posted on August 22, 2016 by Craig Anderson in Guest Blogs

This is one of 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. For a list of Craig's previous posts, see the list of "Blogs by Craig Anderson" in the sidebar below. This post originally appeared in November 2015.

Attaching Corner Trim on Walls With Rigid Foam

Posted on August 19, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Many readers have built homes with 4 inches or 6 inches of rigid foam on the exterior side of their walls. Typically, these walls include vertical 1x4 furring strips, 16 inches or 24 inches on center, on the exterior side of the rigid foam. The furring strips perform at least three functions: they hold the foam in place, they create a rainscreenConstruction detail appropriate for all but the driest climates to prevent moisture entry and to extend the life of siding and sheathing materials; most commonly produced by installing thin strapping to hold the siding away from the sheathing by a quarter-inch to three-quarters of an inch. gap, and they provide something for the siding to be fastened to.

It’s Time to Plan for Electric Vehicles on the Grid

Posted on August 18, 2016 by Anonymous in Guest Blogs


If you think electric vehicles are still a niche technology, think again. The International Energy Agency (IEA) estimates that more than 1 million electric vehicles (EVs) were on the road in 2015, including 400,000 in the United States. In order to limit global warming to 2 C° or less, the agency says the world will need 150 million EVs by 2030 and 1 billion by 2050, implying a 21% compound annual growth rate from now until 2050.

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