Passive House in the (Wisconsin) Woods
A Passive House project nearing completion on the state’s western border aims for energy-positive performance and a high profile
Passive HouseA residential building construction standard requiring very low levels of air leakage, very high levels of insulation, and windows with a very low U-factor. Developed in the early 1990s by Bo Adamson and Wolfgang Feist, the standard is now promoted by the Passivhaus Institut in Darmstadt, Germany. To meet the standard, a home must have an infiltration rate no greater than 0.60 AC/H @ 50 pascals, a maximum annual heating energy use of 15 kWh per square meter (4,755 Btu per square foot), a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot). The standard recommends, but does not require, a maximum design heating load of 10 W per square meter and windows with a maximum U-factor of 0.14. The Passivhaus standard was developed for buildings in central and northern Europe; efforts are underway to clarify the best techniques to achieve the standard for buildings in hot climates. residential construction is still such a rarity and curiousity in the U.S. that many projects designed to meet the standard have their own blog forum and accompanying photo galleries. Passive House in the Woods, in Hudson, Wisconsin, is one such project.
The progress of Passive House in the Woods, or PHitW, has been assiduously documented by its designer, Tim Delhey Eian of Minneapolis-based TE Studio, and the project builder, Morr Construction Services of Shoreview, Minnesota. At this point in the emergence of Passive House in North America, PHitW is among 23 single-family residential projects that have been certified or pre-certified by Passive House Institute U.S. The Midwest, in turns out, is home to a bunch of them. There are, for example, eight in Illinois, where there also are two planned Passive House retrofits and two planned multifamily projects aiming for Passive House performance.
PHitW, though, will be a first for Wisconsin and certainly an anomaly in Hudson, which is about 20 miles east of St. Paul, Minnesota.
Hoping it will inspire others to build to the standard
By the end of last week, exterior insulation was being installed on the three-story, three-bedroom 1,940-sq.-ft. house, which likely will be completed by early summer. Constructed with insulated concrete forms, the exterior walls are expected to provide R-70 thermal resistance, while the slab is designed to deliver R-60 and the roof R-95. The rooftop will serve as an observation deck and accommodate a 4-by-10-ft. solar thermal collector. Electric power will be provided by a 4.7 kW solar power system, whose average annual output is calculated at 6,750 kWh, enough to cover the home’s predicted 4,200 kWh annual usage and feed power back into the grid.
The attached garage is built with advanced stick framing to reduce the amount of wood used and is clad in exterior-grade gypsum sheathingMaterial, usually plywood or oriented strand board (OSB), but sometimes wooden boards, installed on the exterior of wall studs, rafters, or roof trusses; siding or roofing installed on the sheathing—sometimes over strapping to create a rainscreen. . To avoid air transfer from the garage to the house, there is no door connecting the two buildings; rather, the garage features two doors for vehicles and a south-facing door for pedestrian access. The garage’s flat roof is designed to accommodate a layer of tray-planted sedums, helping improve the view from the house rooftop, while water runoff will be captured in rain barrels for use elsewhere on the site.
The home’s owner, Gary Konkol, a general-practice physician, recently told the Hudson-Star Observer that with his focus on the use of sustainable materials and desire to live in a home built to such a high performance standard, “I’m putting more into it than I’ll ever get out of it financially. But I’ll get other things out of it.” His hope, he says, is that the home serves as a model that will encourage construction of others that meet Passive House criteria.
- Tim Delhey Eian/TE Studio
May 17, 2010 3:32 AM ET