The most recent blogs at Green Building Advisor

Does a Passive House Use 90 Percent Less Energy?

Posted on April 14, 2017 by Martin Holladay in Musings of an Energy Nerd

Longtime readers of GBAGreenBuildingAdvisor.com know that I get frustrated by exaggerated energy savings claims. A glaring example is the statement that “a 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. building uses 90% less energy than a conventional building.” A variation on this claim: “A Passive House building uses 90% less energy than a code-minimum building.”

Trump Budget Threatens to Leave Poor Families in the Cold

Posted on April 13, 2017 by Anonymous in Guest Blogs

By KHALIL SHAHYD

When her furnace started acting up, Alicia Dickenson knew her family had a problem. “I’m not going to have money for a new furnace,” the Ohio resident told her local paper. “How am I going to make it through the next winter?” When Dickenson found out that she qualified for home weatherization — including an upgraded, more efficient furnace — her relief was immense. “Huge,” she said.

Five Ways to Do Balanced Ventilation

Posted on April 12, 2017 by Allison A. Bailes III, PhD in Building Science

Ventilation is a great thing. Bringing outdoor air into the home and exhausting stale indoor air improves indoor air quality. Well, most of the time, anyway. Sometimes the outdoor air quality is worse than indoor air. Sometimes you bring in too much humidity and start growing mold. And sometimes you bring in the wrong outdoor air. But the issue of outdoor air vs. indoor air is a topic for another article.

No Reason to Delay Efficiency Standards

Posted on April 11, 2017 by Anonymous in Guest Blogs

By LAUREN URBANEK

The U.S. Department of Energy (DOEUnited States Department of Energy.) issued delay notices in mid-March for two energy efficiency standards and three test procedures, which does nothing but create uncertainty for manufacturers and industry where there should be none. Taken together, these standards (including the standards supported by the test procedures) will save consumers more than $28 billion over 30 years of product shipments.

Toronto Passive: Some Thoughts on Drainwater Heat Recovery

Posted on April 10, 2017 by Lyndon Than in Guest Blogs

Editor's Note: Lyndon Than is a professional engineer and Certified 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. Consultant who took a year off from work to design and build a home with his wife Phi in North York, a district of Toronto, Ontario. A list of Lyndon's previous blogs at GBAGreenBuildingAdvisor.com appears in the sidebar below. For more, you can follow his blog, Passive House Toronto.

Two Views of Double-Stud Walls

Posted on April 7, 2017 by Martin Holladay in Musings of an Energy Nerd

At the recent BuildingEnergy 17 conference in Boston, there were at least two presentations that touched on double-stud walls. John Straube, a professor of building envelopeExterior components of a house that provide protection from colder (and warmer) outdoor temperatures and precipitation; includes the house foundation, framed exterior walls, roof or ceiling, and insulation, and air sealing materials. science at the University of Waterloo in Ontario, used his presentation to raise a warning flag, noting that “these walls will work if everything works — if there aren’t any defects — but they don’t work if there is something wrong.”

Does Green Energy Have Hidden Health and Environmental Costs?

Posted on April 6, 2017 by Anonymous in Guest Blogs

By EDGAR HERTWICH, ANDERS ARVESEN, SANGWON SUH, and THOMAS GIBON

There are a number of available low-carbon technologies to generate electricity. But are they really better than fossil fuels and nuclear power?

To answer that question, one needs to compare not just the emissions of different power sources but also the health benefits and the threats to ecosystems of green energy.

Why We Still Need to Discuss Grid Defection

Posted on April 5, 2017 by Anonymous in Guest Blogs

By JAMES MANDEL, MARK DYSON, and TODD ZERANSKI

The rapidly declining costs of distributed energy resources (DERs), including rooftop photovoltaics (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.) and behind-the-meter batteries, have introduced new dynamics into a traditionally slow-moving electricity industry. This paradigm shift has ushered us into a new era where previous assumptions about how, where, and at what scale electricity is best generated, transmitted, and distributed may no longer hold.

Just Say No to (Swiss) Cheesy Attic Floors

Posted on April 4, 2017 by Greg Labbe in Guest Blogs

As the biting cold of winter hit the Great Lakes area last December, many building owners started to see signs of moisture damage on parts of their walls and ceilings. As we keep indoor temperatures consistent while the outdoor temperature drops, the difference between indoor and outdoor temperatures (the ole’ Delta T, as they call it) becomes greater. This difference pushes indoor air upward; if there are leaks in the ceiling, the air goes up and out and into the cold attic space. That’s the stack effectAlso referred to as the chimney effect, this is one of three primary forces that drives air leakage in buildings. When warm air is in a column (such as a building), its buoyancy pulls colder air in low in buildings as the buoyant air exerts pressure to escape out the top. The pressure of stack effect is proportional to the height of the column of air and the temperature difference between the air in the column and ambient air. Stack effect is much stronger in cold climates during the heating season than in hot climates during the cooling season. — slightly less powerful than the force Darth Vader uses, but equally nefarious.

Are Ductless Minisplits Overpriced?

Posted on April 3, 2017 by Scott Gibson in Q&A Spotlight

Ductless minisplit heat pumps have received a tremendous amount of attention in the last several years, and Peter L. would like to include one in his own house. There's only one problem: an estimate that seems far higher than it should.

"I was quoted $4,800 to purchase and install a Mitsubishi Mr. Slim 1-ton unit (MSZFE12NA)," Peter writes at GBA's Q&A forum. "That seems very high. Especially since it's a new build and the 3-inch hole is already in the wall."

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