Prototype unites green building techniques

By Ethan Andrews
VillageSoup/Waldo County Citizen Reporter

UNITY (June 28): A prototype house is going up on the campus of Unity College that could be a model for sustainable residential construction.

If all goes according to plan, it will take less than a month to erect, will reconfigure itself in more ways than a Swiss Army knife, will burn no oil and may produce more energy than it consumes.

It’s also far from perfect, but that may be the thing that makes it work.

Unity House in its second week of construction. Site preparations consumed the first week. The house here took one week to erect and will take one more to complete. (Photo by Ethan Andrews)

Philip Henry, a timber-framing specialist with Bensonwood, works on the exterior of Unity House. (Photo by Ethan Andrews)

“Unity House” sprung from a collaboration between Bensonwood Builders and the Massachusetts Institute of Technology’s Open Source Building Alliance. The Open Prototype Initiative, as the collaborative effort is called, aims to complete four buildings, of which Unity House is the second. The first, a brain injury rehabilitation center at Crotched Mountain, Greenfield, N.H., was completed in 2006.

Unity College netted the project in part because of the longtime friendship between Unity President Mitchell Thomashow and Tedd Benson of Bensonwood, who met when Thomashow was at Antioch New England in Keene, N.H.

When Thomashow came to Unity College in 2006, the school was looking to build a president’s house and the “green” aspects appealed to the mission of “America’s Environmental College.”

The environmental focus of Unity College and the principles of "open building" both took shape in the 1970s, when progressive theories across all disciplines were converging on a single topic: The earth and the long-term survival of the human race.

Some people went “back to the land,” but many have maintained that the question of “sustainability” in an already-industrialized world would have to be answered through industrial innovations.

John Harbraken pioneered "open building" with its strategy of “disentanglement” at MIT in the 1970s. OPI follows directly from Harbraken’s work through his successor, Kent Larson, who advised the Unity House project.

An abandoned Web cam housing at the perimeter of the Unity House site. (Photo by Ethan Andrews)

Open building views any dwelling in terms of layers: The site, the structure, the skin, the space plan, the services and the “stuff” within the home. Keeping these layers separate allows for modifications to any of the layers during the life of the building, with minimal impact to the other layers.

Benson began working with open building principles in his timber-frame homes 15 years ago. As it turns out, the “point load” construction of barns and warehouses are inherently “disentangled.” By contrast to stick-frame houses, which rely on their walls for strength, timber-frame houses can be stripped to a bare skeleton without weakening the building.

Unity House is, at its core, a timber-frame house. The structural beams that would historically have been a single piece of timber have been replaced with glue-laminated yellow pine in order to meet a higher environmental standard.

Beyond the skeleton, Unity House has a very contemporary look. An architect’s rendering of the finished interior, with only a grand piano for furnishings, looks like an advertisement for a high-end metropolitan condominium.

An uninterrupted sheathing of double-thick blue foam insulation wraps the house, and removable prefinished panels will replace drywall in the interior to facilitate easy access to electrical and plumbing.

Using three-dimensional modeling software and computerized numerically controlled machinery, Bensonwood was able to precut and, in many cases, prefabricate the sections of the house at their Walpole, N.H., shop. As a result, waste at the site is almost nonexistent. Waste at the shop gets directly reused or fed to the shop’s gas-augmented wood boiler.

Unity House uses some time-tested methods amid the new technologies. Southern exposure provides “passive solar” heat, while a raft of solar panels, suggesting a peaked roof on the flat-roofed dwelling, provides the electricity for the home. When the sun shines less and it’s colder outside, the house draws additional energy from the grid. Over the course of the year, Bensonwood expects the house, on balance, to produce more energy than it consumes.

Technically, Unity House is a prototype, but many of its most appealing features are already incorporated in Bensonwood’s architectural practice.

According to Randall Walter, Bensonwood may be as close as three weeks away from being able to take orders for a “Unity House” or “Unity House-like” dwelling.

The 1,930-square-foot home cost around $450,000 to build though future models would benefit from the research and development that went into the prototype. How much the next one will cost remains to be seen.

“If somebody will buy another one and will buy it for ‘X’,” Walter said, “that’s what it costs.”