Like most project managers rushing to complete their homes at the inception of Solar Decathlon 2009, Eric Harmann hasn't had much sleep. But he and his groggy student volunteers from the University of Wisconsin-Milwaukee made time to show off their Decathlon entry to PM last week, starting with its wavy, sinuous rain screen siding. At first glance, the crooked boards look like lumber pile rejects. But peer more closely, and the distorted shapes reveal carefully contoured waves, which Harrmann says are meant to evoke the natural landscape of Wisconsin's Menomonee Valley. That regional landscape was carved out, along with the Great Lakes, when glaciers retreated across North America. As Harrmann puts it: "You might say this house is glacially inspired."
The house certainly contains the same stark relief that a glacier can leave on a landscape. The roof is an inverted apex, with a ridge beam running lengthwise like a valley down the house's center, then rising to high points on each side. Clerestory windows tracing the chaotic roofline proceed as out-of-square polygons around the house's perimeter.
Despite the scarcity of plumb lines and level surfaces, the house feels quite orderly. The ridge beam draws a visitor through the space, "guiding you from the entry to the exit," according to Harrmann. Generous use of Murphy bed-style built-ins also organize the rooms by assigning specific tasks to open areas--a fold-down breakfast table and tucked-away island define the kitchen, a fold-down bed and movable entertainment system denote the bedroom--and all of these furnishings retract neatly into walls. Cherry-clad cabinets conceal the furnishings behind intricate, tight-fitting joints. Milwaukee would ace an examination of its woodwork--too bad the Solar Decathlon doesn't judge that category.
What the contest will measure are the triple-paned windows framed in walnut and Paperstone (a post-consumer recycled product), designed especially for the school by the H-Window Company in Wisconsin. These windows, which lose almost no heat through their panes or casings, borrow principles from the passive house approach to building. The students took more steps to eliminate heat loss, known as thermal bridging, by staggering their exterior stud walls so that a continuous layer of Icynene insulation would be woven throughout the walls in an unbroken heat-trapping barrier.* To ensure that the least amount of energy is used to condition the space, multiple thermometers take an average temperature rating, and an efficient heat pump uses an energy-recovery system to warm or cool specific zones within the house. By reducing heating and cooling demands in Milwaukee's harsh environment, Harrmann and his crew hope the Meltwater house--and its crown of solar panels atop that skewed roof--can put more power onto the grid than the home consumes.
Maximum photovoltaic production under optimum conditions: 5.6-kW per hour.
* This sentence was changed to more accurately define "thermal bridging," which is another term for heat loss. Thanks to the commenter below.