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Site Sensitivity

Posted by Suchi Rudra

Sep 15, 2014 4:57:57 PM

WHEN KAREN AND DAVE DAVIS decided to build a second home in Martha’s Vineyard with absolute minimum environmental impact, they chose to work with local design/build firm South Mountain Company. Founder John Abrams and his team had been building finely crafted and sustainable houses since 1975, and quickly realized that the site for this particular house near Chilmark Pond was a designer’s dream: a south-facing slope with wonderful views of the south shore. However, this very slope and the narrowness of the site also proved challenging to work around.

“Zoning restrictions regulated the height, roof pitch and footprint, and we also wanted to be very conscientious of the view of the building from the beach and the neighbors downhill,” says Abrams. “Additionally, the traffic on South Road moves noisily by the house just to the north.”

These factors led the team to build into the hillside, burying the side of the house that is exposed to the road and winter winds, and opening up the house on the south side “like a flower” to the sun and the view. A large part of the 3,300-square-foot, four-bedroom house is below grade, making the house feel smaller than it is. By using the basement as living space and shifting it out from under the first floor, Abrams says the house becomes less massive from the south and the feeling of being in a basement is diminished. Part of the house has a living roof, which replaces some of the rain absorption area that is typically removed when a building covers the land.

Abundant daylight is delivered to the northernmost rooms and basement through a clerestory that arches in the middle “to mimic the path of the sun,” and via strategically placed interior windows and glass block in the floor. Good daylighting, as well as efficient appliances and fixtures, helps to reduce electrical demands.

To minimize fossil fuel use and energy consumption while maximizing comfort and simplifying operation, South Mountain focused on creating a super energy-efficient building envelope. Combining this with passive solar strategies allows the house to be left unheated in the winter without freezing. The envelope also keeps the house cool in the summer—and with the help of ocean breezes, there’s no need for air conditioning.

Solar energy from a PV solar array on the garage roof is harnessed to heat water and produces enough electricity to offset household consumption, including the electricity that was consumed during the home’s construction. The solar electric system was sized to match predicted future energy demand of a part-time residence, but can be upgraded if the house is occupied full time.

Abrams finds that building net-zero houses, at least locally, tends to cost 7 to 10 percent more in terms of initial capital investment than a typical house built to code, but the investments pay off. Since March 2008, the Davis home has consumed 39,950 kWh (6,323 kWh/year) and generated 44,708 kWh (7,077 kWh/year). The solar has net metering, so the family receives energy from the grid as needed and exports the excess.

Most materials in the building are salvaged, procured from renewable sources or are easy to recycle. The materials were specifically chosen to be timeless and “not necessary to replace once out of fashion,” Abrams adds.

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Topics: net-zero energy, graywater, passive solar, 2600 to 3400 square feet, green roof, Low-E Window glazing, salvaged materials, Building Envelope

Helios NW Eco: A Net Zero Vacation Home

Posted by Suchi Rudra

Sep 12, 2014 6:16:00 PM

WHEN SARAH AND HER HUSBAND (surnames withheld) purchased what is now the Helios Eco-House in Bend, Oregon, the primary goal was to achieve LEED standards. But after doing much research, the biotech and engineer couple discovered that “if you’re willing to go a little further, it’s really painless to go net zero.”

When the couple purchased the 2,145-square-foot house in 2010, construction hadn’t been completed due to the drop in the housing market in 2006. Sarah considered this a unique opportunity.
“It’s one thing to read about green building, and another to immerse yourself in it,” she says. By March 2011, the couple completed construction on the three-bedroom, three-bath house to achieve LEED Gold for Homes (the first in Oregon), and the property began to operate as a short-term vacation rental. The rental income was immediately reinvested into the house, including the installation of the PV array, and by June 2011, Helios Eco-House had achieved net-zero energy.

“It’s the only net-zero property in the area that I know of,” Sarah says.

Powering the home is a 2.59-kW grid-tied photovoltaic solar panel array on the roof. Each solar panel has its own microinverter, which leaves the whole array unaffected if one panel breaks down. “Little decisions like that helped maximize what we’re doing,” Sarah adds.

Typically, the house is able to send back excess energy into the grid on a monthly basis, except for a small dip in January and February, depending on the snowload. But Bend is located in what’s known as a “high desert” climate and enjoys a prime solar environment, with over 300 days of sun a year. A display in the garage and online allows visitors to monitor the performance level of the PV array.
Guests can leave a minimal carbon footprint by walking to local restaurants, cafés and markets and cycling or taking a shuttle bus to nearby attractions. The house also maintains a “mid-century modern” aesthetic, complete with vintage furniture, which allows guests to try out an eco-friendly lifestyle without sacrificing ease or comfort.

“People can stay very comfortably and not have a lot of waste as a result of their stay,” says Sarah. “And other guests come because they are specifically interested in the concept of this house.”

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Topics: net-zero energy, 1600 to 2500 square feet, Green Landscaping, LEED, solar, standing seam metal roof, water conservation, zero-VOC, radiant heating systems, Low-E Window glazing

Energy Efficient for Peace of Mind

Posted by Green Builder Staff

Sep 4, 2014 2:11:03 PM

IT'S NOT ALWAYS easy to build an affordable green home without a glaring compromise or two. But architect Eric Hughes and builder Dan Vos somehow beat the odds.

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Topics: net-zero energy, Bamboo, High-Performance Windows, LEED, SIPs, Indoor Air Quality, ICFs, 1500 square feet or less, passive solar, zero-VOC, 2011 Green Home of the Year Awards

Future Proof: Good Building Science Leads to Net Zero

Posted by Green Builder Staff

Sep 4, 2014 1:46:37 PM

"FROM THE OUTSET we designed this house to maximize south facing roof space,” notes architect Bruce Coldham. “We modeled the site digitally, and look at trees and sun angles. From the get-go full on solar power was the first priority.”

Wright Builders of Northampton, Mass., framed the house with double 2” x 4” walls, a decision influenced by Building America’s years of research on wall efficiency. Coldham says most of the homes his firm designs now—even affordable ones—are framed this way, with either double 4” studs or with 2” x 6” studs that have a layer of rigid foam acting as a thermal break on the home’s exterior.

This house is exceptional by any standards, in part because the team conducted blower door tests at intervals during construction, using a theatrical smoke machine to help pinpoint unwanted air infiltration.
“Buildings are gonna last a long time,” notes Coldham. “But if you build like this you don’t have to try to predict when energy costs will rise.  You’ve already sealed the envelope completely. That way when costs do rise—which is inevitable—these owners will be ready.”
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Topics: net-zero energy, HERS, Building Science, 2011 Green Home of the Year Awards

Reclaimed Design

Posted by Green Builder Staff

Aug 4, 2014 4:35:00 PM

WHEN THE OWNERS of this 1,015-square-foot weekend lake cabin explained their dream to builder Don Ferrier, they told him they wanted the house to look like it had been there for 100 years. What they got is a net-zero gem that is currently the greenest house in Texas, per the Green Built Texas certification program.

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Topics: net-zero energy, 1500 square feet or less, standing seam metal roof, salvaged materials


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