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).

Success with Partnerships

As with most affiliates, Habitat EBSV depends on partnerships, including some of the national organization’s sponsors. For example, an ongoing partnership with Simpson Strong-Tie helps further the affiliate’s goal of reducing wood, as the company is willing to fabricate custom brackets. Tipping Engineering, a “super-inventive” Berkeley-based structural engineering firm, offered pro bono services on the Edes Avenue project and suggested many of the advanced framing techniques that were eventually implemented.

Since 2002, every new home that Habitat EBSV builds has included a PV array, donated by Pacific Gas & Electric Company’s Solar Habitat Program and Grid Alternatives, a national nonprofit that provides volunteer labor to install PV arrays on low-income housing. Though the size depends on the roof area, the arrays usually range between 2.1 and 2.5 kW. On average, the arrays save homeowners $500 each year.

Like all affiliates, Habitat EBSV relies on volunteer labor, including “sweat equity” from homeowners. In addition to paid staff, AmeriCorps provides skilled labor over 11-month (minimum) terms—in exchange, they receive a living and rental stipend, and an education award at the end of their terms. AmeriCorps workers undergo extensive training, including an intensive two-week orientation in the fall and a series of 15 clinics throughout the year which cover every aspect of building—from home design and sustainable construction to safety and scheduling.

The AmeriCorps members work under a construction supervisor, such as Grubb, and they in turn coordinate groups of volunteers. This way, as many as 40 to 50 people may be working on a project at one time. Long-time volunteers, such as Oakland resident Laura Goderez, sometimes coordinate small groups of less-experienced volunteers, as well. Goderez, who was first attracted to Habitat for Humanity through President Jimmy Carter’s work, has been volunteering for Habitat EBSV for more than 20 years. During this time, she has noticed changes in both materials and building techniques; for example, she remembers when houses were built with studs 16 in. on center rather than 24 in. Goderez says she enjoys the constant learning. “I’ve learned a lot about building, and I know what’s ‘behind the walls’ of the homes I’ve helped build.”

The affiliate continues to explore methods of increasing its projects’ energy and cost efficiency. According to Grubb, newer projects reveal a more nuanced approach to passive solar design—for instance, sizing, locating, and shading windows to optimize solar gain in winter and minimize it in the cooling season. The designs also cluster kitchens and baths in proximity to shorten water lines, to use less energy heating water. The affiliate seeks to reduce framing materials in part by pre-cutting as much lumber as possible, so it arrives on-site as a kit, and by re-using scrap lumber for blocking. The projects also consider lifestyle impacts by strategically locating them near public transportation, and confining parking to garages on the bottom floor. As of this writing, Habitat EBSV is working on a 20-home development in Martinez, a 30-home condo project in Fremont, and a 42-home duplex development in Walnut Creek.

A demonstration home funded by a grant from Samsung enables Habitat EBSV to try out new techniques and systems, including “headerless” windows, which transfer loads to the rim joist or truss system, and a variable refrigerant flow (VRF) heat pump system. Grubb says they are seeking feedback from homeowners and studying utility bills to learn the impact of these techniques.

Goderez, the long-time volunteer, says she is proud to be associated with an organization that is at the forefront of green building. But in the end, it’s the homeowners that keep her coming back.

“At the end of one day, I happened to be standing near the house of one of the homeowners,” says Goderez. “He came out, saw me, and said, ‘I have to go run an errand, but when I come back I want to invite you for a cup of coffee....in my house.’ That is what makes me keep working with Habitat. I know I made a difference for that man and his family.”

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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