The most recent blogs at Green Building Advisor

What Is the Ideal Relative Humidity in Winter?

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

It was a little crackly around here recently. We had a cold spell in Atlanta, with high temperatures right around the freezing point. As a result, the indoor relative humidity dropped and we got some static electricity.

Even better, what I call the Southern Lights were visible at night, too. (I've never called it that before, but hey, a man named Allison is entitled to make things up on the spot.) That's when the microfiber blanket on the bed lights up every time I move.

Blue Heron EcoHaus: Picking High-Performance Windows

Posted on February 23, 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 How Small Can We Go? The blog below was originally published in May 2015.

Piping as Poison

Posted on February 22, 2016 by Chris Sellers in Guest Blogs

As the crisis over the water in Flint, Michigan, rolls on, we’re learning more and more about the irresponsibility and callousness of officials and politicians in charge.

The mix of austerity politics, environmental racism, and sheer ineptitude makes for a shocking brew, yet the physical conditions that have made it literally toxic for Flint residents are neither as exceptional nor as recent as much of the media coverage suggests.

How to Design a Wall

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

Builders love to talk about walls. Almost all of us are willing to argue about the best way to build a high-R wall, and we love to debate whether certain wall details are environmentally friendly enough to be considered “green.”

Although these conversations can be fun, our obsession with wall details is often misplaced. Details that inflame our passions are often irrelevant. In most cases, we should just choose a relatively airtight easy-to-build wall with good flashing details — one with an R-valueMeasure of resistance to heat flow; the higher the R-value, the lower the heat loss. The inverse of U-factor. in the range of R-20 to R-40 — and be done with it.

A Report from the Passivhaus Front Lines

Posted on February 18, 2016 by Catherine Ruddell in Guest Blogs

Editor's note: Canada's northernmost certified 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. is an 1,895-square-foot home in Fort St. John, British Columbia, where the average number of heating degree days over the last five years has been more than 10,500 annually. The house, completed in 2014, is owned by the city and was described in a Green Building Advisor report in 2014. For more than a year, the house has been occupied by two caretakers, Catherine Ruddell and Paul Gillis, who act as hosts for tours of the project. Catherine recently sent this report of what it's been like to live there.

What Should Be Done With This House?

Posted on February 17, 2016 by Paul Eldrenkamp and Ken Neuhauser in Guest Blogs

In this blog, Paul Eldrenkamp and Ken Neuhauser look at a range of houses and ask these questions: “If this house is to be part of the solution rather than part of the problem in the year 2050, what will it probably look like? What sort of master plan will get it there?” Paul and Ken will be presenting a workshop on this topic (“What should be done with this house?”) at the upcoming BuildingEnergy 16 conference in Boston.

Desperately Seeking Quality

Posted on February 16, 2016 by Carl Seville, GBA Advisor in Green Building Curmudgeon

It’s been quite a while since my last post. The good news is that the recession is over and business is good, leaving me little time to write these days. The bad news is that there is so much work going on, which, combined with a shortage of skilled labor, ends up with large knowledge and communication gaps that create problems in the field.

Solar Now or Later?

Posted on February 15, 2016 by Scott Gibson in Q&A Spotlight

Prices for photovoltaic(PV) Generation of electricity directly from sunlight. A photovoltaic cell has no moving parts; electrons are energized by sunlight and result in current flow. (PVPhotovoltaics. Generation of electricity directly from sunlight. A photovoltaic (PV) cell has no moving parts; electrons are energized by sunlight and result in current flow.) systems have been dropping steadily, making the investment in residential-sized arrays more appealing than ever. Lower prices and a decision in Congress to extend the federal investment tax credit means that ever larger systems are within reach of more homeowners.

But what about homeowners whose construction budgets strictly limit the size of the PV system they can realistically afford? They are people like James Timmerberg, who is building an all-electric house in Ohio and would like to invest in solar — if it makes economic sense.

Insulating Walls in an Old House With No Sheathing

Posted on February 12, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

When the owners of an old wood-framed building say that they’re doing a “gut rehab job,” that usually means that they’re demolishing the lath-and-plaster walls to expose the studs — the first step of renovation work that usually includes new wiring, new plumbing, and new insulation.

Green Groups Harness Data from Space

Posted on February 11, 2016 by Jacques Leslie in Guest Blogs

When Brian Schwartz, a Johns Hopkins University epidemiologist researching the public health impacts of hydraulic fracturing, read about an environmental group that uses satellite imagery and aerial photography to track environmental degradation, he was intrigued.

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