The most recent blogs at Green Building Advisor

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.

Air Flow Pathways in a Leaky Exterior Wall

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

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.

The True Cost of Electricity

Posted on May 31, 2016 by Ferit Ucar in Guest Blogs

This is the second of a four-part series that takes a deep dive into the economics of our electric system and the role pricing can play in accelerating the clean energy economy. The first article in the series was Transforming the Electric System.

Blue Heron EcoHaus: Placing the Concrete Floors

Posted on May 30, 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 Adding Walls and Roof. The blog below was originally published in July 2015. (A complete list of Kent Earle's GBA blogs is provided in the “Related articles” sidebar below.)

How Much Insulation is Too Much?

Posted on May 27, 2016 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

In a presentation at this year’s BuildingEnergy 16 conference in Boston, three energy experts joined forces to tackle a common question: “How much insulation is enough and how much is too much?”

The presentation had an opaque title and subtitle: “How We Sleep at Night: Energy Metrics and Decision Making in Residential Design.” Although presenters' intended meaning may have been obscure, they were trying to answer two questions: At what point are envelope improvements a waste of money? And what metrics or rules of thumb should we use to determine when enough is enough?

Getting More Energy from the Sun

Posted on May 26, 2016 by Tara Dhakal in Guest Blogs

Global demand for energy is increasing by the hour as developing countries move toward industrialization. Experts estimate that by the year 2050, worldwide demand for electricity may reach 30 terawatts (TW). For perspective, one terawatt is roughly equal to the power of 1.3 billion horses.

Energy from the sun is limitless – the sun provides us 120,000 TW of power at any given instant – and it is free. But today solar energy provides only about 1% of the world’s electricity. The critical challenge is making it less expensive to convert photo-energy into usable electrical energy.

Register for a free account and join the conversation


Get a free account and join the conversation!
Become a GBA PRO!