the Construction

Assembly of the two modules at Huntington HomesWhen the Delta T-90 House is on public display during Solar Decathlon 2013, it will be commercially available by Huntington Homes, Inc. of East Montpelier, Vermont. Our mission mandates an approach to construction that capitalizes on local labor and materials as well as off-site prefabrication systems.  A modular home manufacturing company and its assembly line based methods help the Delta-T 90 House optimize material use, build quality, and long-term energy performance.  This approach ensures an exceptional level of craft while maximizing construction efficiency.

The ∆T90 team has the benefit of working with a distinguished palette of materials. Locally harvested hemlock from Norwich University’s own Paine Mountain, and Northern White Cedar from Vermont’s Northeast Kingdom are among the materials that make the Delta-T 90 house to the German engineered Intus windows, we have carefully selected each product based on the highest cost/benefit ratio.

THE ENVELOPE

Delta T-90 member Brenden Brogan on the construction assembly.Cold climates like Vermont can see radical diurnal temperature swings. In light of this, the envelope of the Delta T90 House repels 100% of bulk water, but allows moisture vapor to migrate as needed through the wall assembly, preventing moisture build-up in the wall cavity.

The thermal envelope of the ∆T90 house does not use any closed-cell foam or concrete products. Closed cell foam insulation products have many times the Global Warming Potential (GWP) of dense-packed cellulose insulation. Like many in our bio-region, we recognize that minimizing the overall GWP of new construction is smart for our  immediate health, long-term sustainability, and global (and local!) economy. We also recognize the importance of building wall assemblies that allow moisture to escape, while minimizing heat-loss through conduction and convection. The envelope of the Delta-T 90 house uses high performance tapes and thermal membranes that provide three air-sealed layers. With this, we eliminate air leaks and the likelihood of the dew point to occurring within the wall, floor, or roof cavities.

FLOOR

R – Value 53

The bottom of the house is protected by a half-inch layer of pressure treated plywood with taped joints, which provides a moisture and air barrier. The floor will be supported by 14″ wood I joists spaced 24″ on center, connecting the central 4″X14″ engineered parallel strand lumber (PSL) beams. Fourteen inches of dense pack cellulose insulation will sit within the beams and joists while producing an R-Value of 53. Atop the insulation is a 1 1/8″ plywood subfloor, finished with an additional half-inch of oriented strand board (OSB) floor for the interior finishing.

WALLS

Vertical cross section of external wall.R – Value 50.6

Using an inline advanced framing technique, the walls consist of  engineered lumber 2×12 top and bottom plates with double 2×4 studs at 24″ on center. The wall cavity is  insulated with 11 1/4″ of dense pack cellulose and sheathed in rigid mineral wool. The use of 1×3 strapping boards create a 3/4″ air gap for moisture to evaporate out of the attached wooden rain screen.

WINDOWS

R – Value 8

The Intus Eforte: Passive House Windows and Doors

Vertical cross section of Intus Eforte window installed in exterior wallThese German made triple pane windows are designed for Passive House standards in the coldest climates. With a total R-value of 11.36, the window assembly allows minimal energy loss compared to typical insulated glass units. The tilt/turn sash enables the window to obtain maximum operability allowing passive ventilation when open and an air tight seal when closed.

Custom fabricated windows allows for optimized fenestration of the Delta T90 House . An alteration in glass square footage, shape, and sash enables each window to purposefully serve each space. The 70 square foot window in south wall of the living space allows for maximum solar gain during the colder months, as well as a generous source of direct and ambient light for all public spaces. This single fixed window also allows the living space to flow into the surrounding landscape.  Window placement in the Delta-T 90 House was a critical decision.

The Fakro FTT U6 – 02 High Performance Skylight

Horizontal cross section of installed Fakro skylightDesigned to Passive House Standards, this triple pane, triple air sealed skylight allows for maximum performance with an overall R-Value of 10. Placed in the center of The Delta T-90 house the skylight allows natural light to occupy the core of the space. This centrally located skylight also functions as a ventilation route, pulling fresh air from the exterior windows upward, and out through the roof.

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