The most recent blogs at Green Building Advisor

Rainwater Collection Lowers the Impact on a Coastal Site

Posted on April 30, 2015 by Stephen Sullivan in Green Building Blog

I was honored when longtime friend Laura Sewall invited me to design her house at Small Point, Maine. Set at the mouth of the Sprague River as it spills into the Atlantic, the site witnesses the daily ebb and flow of the ocean’s tides in a vast estuary. Laura saw this dramatic site, the setting for generations of family summer retreats, as a precious gift from her ancestors.

Lstiburek’s Ideal Double-Stud Wall Design

Posted on April 29, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Joe Lstiburek called me last week to set the record straight. I had written an article about a study of moisture in double-stud walls in a Massachusetts home, and his company, Building Science Corporation (BSC), had done the research as part of the Building America program. They found elevated moisture content in the cold, exterior sheathing, and Joe wanted to make sure everyone knew, "I would never build that wall because I consider it too risky."

New Passive House Rules Take Effect

Posted on April 28, 2015 by Scott Gibson in Green Building Blog

Until now, anyone planning to build to the 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. performance standard had a single set of rules to follow. Whether you lived in San Diego or International Falls, Minnesota, buildings could use only a certain amount of energy for heating and cooling, and were allowed a very specific amount of air leakage in the 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..

Is a Ground-Source Heat Pump My Best Bet?

Posted on April 27, 2015 by Scott Gibson in Q&A Spotlight

Cathleen Dalmeida is budgeting for a heating and cooling system as part of an energy retrofit and is wondering whether a heat pumpHeating and cooling system in which specialized refrigerant fluid in a sealed system is alternately evaporated and condensed, changing its state from liquid to vapor by altering its pressure; this phase change allows heat to be transferred into or out of the house. See air-source heat pump and ground-source heat pump. is part of her future. An obvious question: How much do they cost?

"Is there a general rule of thumb for pricing of a ground-source heat pumpHome heating and cooling system that relies on the mass of the earth as the heat source and heat sink. Temperatures underground are relatively constant. Using a ground-source heat pump, heat from fluid circulated through an underground loop is transferred to and/or from the home through a heat exchanger. The energy performance of ground-source heat pumps is usually better than that of air-source heat pumps; ground-source heat pumps also perform better over a wider range of above-ground temperatures. and air-to-water heat pump for a medium sized installation?" she asks in a Q&A post at Green Building Advisor.

Row House Recharged

Posted on April 27, 2015 by Ross Levy in Green Building Blog

I first met Bill and Zahra through a school charity event and soon after designed a new set of stairs for them. A couple of years went by before they called with a bigger project in mind: to expand and rehabilitate their two-unit edwardian home on the sunny south side of San Francisco. The home was a standard San Francisco row house that had been lived in continuously for more than 30 years and was in poor condition. The house needed a lot of work, and the transformation would be dramatic.

Site-Built Ventilation Baffles for Roofs

Posted on April 24, 2015 by Martin Holladay, GBA Advisor in Musings of an Energy Nerd

Roofs often require ventilation channels directly under the 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. — either for a short section of the roof (for example, near the eaves) or for the entire roof, from soffit to ridge. When the wind is blowing, these ventilation channels allow air to move from the soffit vents to the ridge vents.

Ozone Pollution in the West

Posted on April 23, 2015 by Jon Goldstein in Guest Blogs

Long familiar in major urban areas, smog — what we experts call “ground-level ozone” pollution — is quickly becoming a serious problem in the rural mountain west, thanks to rapid expansion in oil and gas development.

Smog has serious health impacts like aggravated asthma, chronic bronchitis, heart attacks, and even premature death. In areas like the Upper Green River Basin in Wyoming, smog levels have sometimes rivaled those in Los Angeles.

Blower Door Testing

Posted on April 23, 2015 by Larry Armanda in Green Building Blog

Air leaks in houses are a big problem. Leaks make homes uncomfortable and expensive to heat and cool. They create condensing cold spots that attract mold and rot. They lead to frozen pipes and make homes less resilient during prolonged power outages.

Is Cold Sheathing in Double-Wall Construction at Risk?

Posted on April 22, 2015 by Allison A. Bailes III, PhD, GBA Advisor in Building Science

Insulation is good. More insulation is better (although at some point, more may not be cost-effective). It reduces the amount of heat a home loses in winter or gains in summer.

White, Wealthy and Whiny: An Environmental Movement in Need of a Makeover

Posted on April 22, 2015 by Peter Dykstra in Guest Blogs

Now that I’ve gotten your attention with an over-the-top headline, understand that I don’t really buy it. Not completely, anyway.

But millions of Americans do, and because of that, pushback against environmental initiatives is both strong and often devoid of reason.

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