A Meadow Homecomments (0) July 16th, 2012 in Project Gallery, 2013 HOUSES Awards Gallery Pin It
When I first met with the owners I sensed at once they were lovers of all things sculptural. They also were committed to sustainable lifestyles and building. And they respected the talent of tradespeople and artisans enough to give them freedom to be their unfettered best. In other words they were an architect's dream.
Their program was simple: a modestly-sized home suitable for themselves and extended visits from friends and family. Their property was likewise simple: an open natural meadow, formerly an apple orchard, with rolling hills and just a dotting of pines.
My appreciation for their site and aesthetics combined with my knowledge of Passive House design and LEED for Homes guidelines, and I set about creating a piece of energy-efficient sculpture for their dwelling. The 2550 sf home replicates the curves of the surrounding hills, using a roof structure that I first saw in Fine Homebuilding when I was a grad student in the early 90s and had hoped to experiment with since: the curve comes not from curved trusses, but from I-joists laid over curved exterior walls. This technique is not only fairly straightforward to construct (with the aid of precise framing plans) but is much less expensive than engineered curved trusses.
From the start of the project, the owners were on board with building a super-insulated home. I designed the shell with virtually no thermal bridging. Structural exterior walls are 2X6, with a 2" gap between that and an interior 2X4 wall, giving a total of 12" thickness. The roof was constructed of 16" I-joists, enclosed at the bottom with plywood. Below that are 3" plates which allow for all wiring to be installed without penetrating the roof envelop. The floor slab rests on 6" of rigid foam insulation, giving the structure a completely unbroken thermal barrier.
My initial Passive House calculations netted an energy use of slightly over 7.0 kBtuh/sf/year compared with Passive House's requirement of 4.75 for certification. I eliminated two corners and an observation tower and managed to reach 4.83 through the use dense-packed locally-produced cellulose insulation and Intus windows and doors which have a U-factor of 0.1287. To reach Passive House certification levels I would have been forced to eliminate some of the northern windows and lose those views, or switch to environmentally damaging foam insulation. Neither were desirable options, so we all agreed we were very satisfied with the energy level we had achieved, and pursued LEED for Homes Platinum certification.
Materials for the home were chosen according to their ability to be recycled at the end of their use. The home is clad with 23% recycled corrugated steel, horizontally oriented, and standing seam roof. Floors are concrete and sustainably harvested Teragren strand bamboo. Countertops are all concrete, fabricated by local concrete artist Dylan Lauger, and cabinets are maple with all low-VOC composition.
From the week the construction contract was awarded, project coordinator Dan Wiesman of Baylakes Builders, and I worked seamlessly with his team to ensure that all LEED requirements were followed. Plumbers, electricians, HVAC and concrete contractors, insulators and landscapers all met together on multiple occasions to understand the LEED process and makes this effort bear fruit. Construction waste was nearly non-existent. Wood scraps were ground and used as mulch; drywall and metals recycled. The meadow was carefully protected from trucks and trampling feet.
Thanks in part to the design of the envelope and in large part to Dan's diligent attention to caulking and sealing every joint, initial review and testing of the house yielded a low HERS rating of 25, a blower door test that may be one of the lowest recorded in the State, and virtually no thermal bridging anywhere in the envelope, as indicated by a thermal imaging review.
The home is expected to be completed by early August and all indicators suggest that it will earn a LEED Platinum rating.
posted in: Project Gallery, 2013 HOUSES Awards Gallery, Energy-Smart, New Construction, 2013