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Trusses on the Tundra

Sustainable Housing Technologies in Southwest Alaska


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Cold Climate Housing Research Center-designed energy-efficient Bethel duplexes under construction earlier this year in February.

Courtesy of CCHRC

It’s cold and windy outside, a typical March day in Bethel, Alaska. The snowpack is thin on the windswept tundra. But it’s warm and cozy inside two new homes on Chief Eddie Hoffman Highway, heated only by construction lights. The Association of Village Council Presidents (AVCP) is building the super-efficient duplexes to house students for its popular aviation school. The homes are made from integrated trusses that connect the roof, walls and floor joists into single units that are tipped up like the ribs of a whale, a clean, simple design for the extremes of the tundra.

 

Integrated trusses before enclosure at the Bethel duplexes.

Courtesy of CCHRC

 

Integrated truss system can be sized to needs.

Courtesy of CCHRC

 

Yuut Yaqungviat, Yup’ik for “Where people get their wings,” trains local pilots for the region, which has the third busiest airport in Alaska. Single-engine turboprops, small bush planes, and cargo aircraft connect dozens of remote villages to just a couple of urban hubs. Air travel is a way of life on the Yukon Kuskokwim River Delta, where forty-eight small villages are spread across an area the size of Oregon with no roads and few centralized services.

Southwest Alaska has been occupied by Yup’ik Eskimo for thousands of years, yet communities have struggled to adapt as the region has rapidly modernized over the past fifty years, shifting from a subsistence lifestyle to a cash economy, from seasonal shelters to modern housing and energy. “The Yukon Kuskokwim region has the lowest per capita income, the highest unemployment, the highest suicide rate. We don’t have tourism. We don’t have oil. We don’t have forestry. We have a rich culture,” says Mike Hoffman, executive vice president for AVCP, a nonprofit tribal organization in Bethel. It was a blow to the region when high operating costs forced the aviation school to close last year. Students couldn’t afford to spend $1,000 a month on energy on top of tuition.

 

 

AVCP hired the Cold Climate Housing Research Center (CCHRC) to design new energy-efficient duplexes for students to help the school reduce its energy burden and re-open its doors. CCHRC is a research center based in Fairbanks that develops and tests sustainable housing solutions for the north.

Bethel is one of the most challenging places to build in Alaska. Sitting in one of the largest deltas in the world, where the Yukon and Kuskokwim rivers empty into the Bering Sea, it is a treeless tundra exposed to wind-driven rain and coastal storms. The soil is constantly shifting, with a high water table and a deep active layer that freezes in the winter and turns to mush in the summer.

 

Bethel duplex designed for aviation school.

Courtesy of CCHRC

 

Most housing in the region was imported from the Lower 48 and has succumbed to moisture, mold, and structural damage over the past few decades. Many are now rotting from the inside out. The average household in Bethel spends $6,500 a year on energy, more than three times the national average, thanks to leaky housing and imported heating oil that runs $6.50 a gallon. Nearly half the homes in the region are overcrowded, with three or more generations often packed into three-bedroom homes.

 

Ice fishing on the Kuskokwim is a tradition dating back thousands of years for area residents.

Courtesy of AVCP

 

Yukon-Kuskokwim region.

Courtesy of CCHRC

 

CCHRC designers worked with AVCP and the community to come up with a design that fit the climate and culture of the region. The prefabricated trusses are built in a factory and shipped in full house-shaped pieces. The units are set and braced two feet apart in a straight line for the full length of the home.

There are several benefits of this design. First, the truss system is easy to build, even for an unskilled crew—five of the six workers in Bethel had no carpentry experience. The prebuilt trusses can be assembled in a single day, rather than a week it would take to stick-frame a home. This saves precious time during the short building season of Alaska and allows crews to get out of the elements quickly. A faster build means lower cost, freeing up money for additional housing.

The truss system also lends itself to super-efficient construction, as the depth of the walls, roof, and floors can be scaled to accommodate more insulation. The Bethel homes are filled with nine inches of polyurethane spray foam for an R-value of approximately 50, more than twice a conventional 2x6 framed wall. In addition, each piece of the truss is comprised of an inner and outer chord with webbing in between, which largely cuts down on conductive heat loss. The trusses can be assembled without heavy equipment, which is scarce in the Bush. “The components are light, and the trusses can be tipped up by four men,” says Jack Hébert, CEO of the research center.

 

Moisture damage.

Courtesy of CCHRC 

 

Because spray foam is vapor impermeable, this design solves the moisture problems that are endemic to the Bethel region, preventing interior vapor from leaking into the walls and condensing on cold surfaces.

 

Integrated trusses being raised by construction workers in Atmautluak without heavy equipment.

Courtesy of CCHRC

 

The integrated truss design is part of a larger effort to build a local construction industry in Bethel, developing a lumber mill upriver and a truss plant in Bethel. Lumber would be sent down the Kuskokwim by barge in the summer and ice roads in the winter, keeping jobs and money in the region. “We’re looking at producing a million board feet of white spruce on the Kuskokwim, so we can build and manufacture our own trusses,” Hoffman says.

 

A white spruce lumber mill upriver from Bethel.

Courtesy of AVCP

 

Nearly four thousand new homes are needed in the Bethel region alone to alleviate overcrowding and replace aging buildings. The integrated truss design is just one of a suite of approaches that addresses the need for affordable housing in rural Alaska. In the Yukon Kuskokwim Delta, AVCP and its partners are using technology and local knowledge to make housing work for the people.

This article originally appeared in the June 2015 print edition of Alaska Business Monthly.

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