Efficiency & Solar Design Pair Up for Affordable Housing

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The Edes Avenue development illustrates Habitat EBSV’s green building, and includes 54 two-, three-, and four-bedroom homes.
The average size of the PV arrays in the Edes Avenue development is 2.3 kW.
Construction techniques must be compatible with the Habitat model, which relies on both paid and volunteer labor.
Passive solar design, which includes south-facing windows with awnings, allows winter solar heat gain but reduces unwanted gain during the cooling season.
Volunteers lay engineered wood flooring.
Partnerships with nonprofit Grid Alternatives and PG&E have enabled every new home to include a PV array.
The Grid Alternatives team closes the DC disconnect on the SunPower inverter for the first time.
A few of the many volunteers who helped Grid Alternatives with PV system installation.
Landscaping with drought-tolerant native plants is one of the affiliate’s strategies for conserving water.

The neat row of nearly new homes on Edes Avenue in East Oakland, California, belies the fact that the neighborhood was once a blighted salvage yard and construction material recycling site. The duplex development includes passive solar design, water-conserving landscaping, and PV arrays on every rooftop, turning a former brownfield site into a model of green building.

On the Greener Path

This development was completed by Habitat for Humanity East Bay Silicon Valley (Habitat EBSV) in 2010 and is now home to 54 families that qualified through Habitat’s application process, which sets minimum and maximum income levels for different household sizes for program eligibility. Habitat EBSV’s large service area, which covers 3,000 square miles across Alameda, Contra Costa, and Santa Clara counties, includes distinct urban challenges. The affiliate often acquires brownfield properties and rehabilitates them with new residential developments, and also performs retrofits on existing homes. In 2000, under the influence of David Sylvester, a “green” general contractor, the organization started focusing on green building.

“That’s when we started thinking about how to reduce wood use in our buildings,” says Ben Grubb, construction manager for Habitat EBSV. Under Sylvester’s leadership, they began using advanced framing techniques (AFTs), which reduce lumber use, allow more insulation, and reduce thermal bridging. These techniques include installing studs 24 inches on center, employing raised heels in the attic framing, and using drywall clips to facilitate the construction of insulated corners.

During a 22-home project in Livermore, the team honed their AFTs and also refined their site design, orienting the homes to optimize rooftop solar PV production and to take advantage of passive solar gain. However, it’s the Edes Avenue development, built in three phases starting in 2006, that showcases the affiliate’s deepening knowledge of green building.

“In each phase, we incorporated more energy-efficiency and indoor air quality (IAQ) features,” says Grubb. In addition to employing several AFTs, they specified zero-VOC paints and zero-formaldehyde finishes, and began using blown-in cellulose in place of insulation that contained formaldehyde. They also started adding radiant barriers to attics and used efficient tankless water heaters that worked well with the compact floorplans. (Today, the affiliate uses both tank-style and tankless water heaters in its developments, depending on unit layout.)

Evolving Efficiency

The Habitat EBSV’s evolution mirrors the national organi­zation’s efforts to boost energy efficiency and overall sustainability. “Habitat has always been focused on providing affordable homes, but they have to be affordable and efficient over the long term,” says Derrick Morris, director of construction at Habitat for Humanity International. About 10 years ago, the organization adopted a national policy to build to Energy Star standards at a minimum. The emphasis on energy efficiency recognizes that viable home ownership depends on more than just an affordable mortgage. Homeowners must also be able to afford to operate and maintain the home, and lowered utility bills are a big part of the equation.

Many affiliates, including Habitat EBSV, go well beyond these standards. Habitat EBSV was using the LEED rating system as a metric of achieving its goals, and has completed LEED Gold- and Platinum-certified homes. The affiliate relies on California’s GreenPoint Rated system, which is more flexible, has a slightly lower entry point, and is tailored to California building codes (see “Build It Green’s GreenPoint Rated System” sidebar).

Comments (2)

John Moore Architect's picture

Great article and great work! Habitat for Humanity North Shore based in Massachusetts is also creating energy efficient homes. 3 homes just finished include solar hot water systems offsetting 70-80% of family owners' annual domestic hot water fossil fuel requirements. System cost was reduced substantially by generous incentives for non-profits through the Massachusetts Clean Energy Center.

Fred Golden's picture

I am glad they provide heat pumps to the homes. Heat pump can provide 100,000 btus for $.80, while natural gas is $1.50, electric baseboard heaters over $3. Oil heaters can cost $4 per 100,000 btus depending on the cost each winter.

Of course with the 2 KW solar system some of that heat is free!

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