Unity College Scores Again With TerraHaus That's Passivhaus
Images credit Unity College Passive House
Unity College says "we're leaders in the environmental movement, focused on sustainability in the classroom and in the real world." When it comes to their buildings, they practice what they teach; their latest accomplishment is TerraHaus, a student residence built to Passivhaus standards and designed by architect Matthew O'Malia and builder Alan Gibson, who also did the GO Home that we admired recently.
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Passivhaus designs tend to be boxy; you want to minimize the surface area and the number of jogs to minimize air infiltration. You also want big windows facing south for passive solar gain. One of the things I loved about the GO Home was the proportioning of the windows in the wall, it just looked right in such a simple form.
TerraHaus has the same windows, projected out in a box. Perhaps it is the beige siding, or the uncomfortable meeting of the two roof planes, but I just don't think that it works as well visually. But look at the way the shadow from the roof overhang exactly covers the upper window. That's what comes of careful design and siting.
The passivhaus standard is achieved by using a lot of insulation, careful detailing, and careful siting to maximize passive heating and minimize active. But in TerraHaus, one learns that all standards have their problems. The Terrahaus blog author ( I think Doug Fox, Director, Center for Sustainability and Global Change) complains about how the Passivhaus standard doesn't account for efficient use of space:
The Passive House standard misses one key energy issue: efficient use of space. The standard uses an energy per floor area measurement (<5,000 Btu/square foot) rather than an energy use per person measurement. While it may not be an issue in Germany, the home of Passivhaus, homes in the United States are getting larger all the time.
I have said the same thing, and been seriously schooled in More on Measuring Energy In Green Building: Absolute vs Relative.
Another issue of standards raised by the author is that of Energy Star windows. Like many builders of Passivhaus buildings, they imported crazy-expensive German windows because they were built to the Passivhaus standard and had high-transmission glass. But because of that glass, they don't comply with Energy Star.
While you will frequently see Unity College promoting Energy Star products, the Energy Star program and the other programs that rely on Energy Star ratings have a flaw when it comes to windows. The very windows we most need in the Northeast--high SHGC windows for southern exposures--are not Energy Star rated and do not qualify for federal and state incentives! The Energy Star program promotes low SHGC windows, which makes sense for homeowners in the South where these windows help keep homes cooler.
It's hard to believe that a window that is good enough for Passivhaus isn't good enough for Energy Star, but that's how it is.
Unity College is also home to Unity House, another architectural test bed, built by Tedd Benson of Bensonwood under his Open Building System, covered at The Open Prototype.
More at the TerraHaus Blog, found on Jetson Green.
More on Passivhaus
Passive R-House Wins AIA Housing Award
Passivhaus: What's In A Name?
Martin Holladay Rattles Cages with Critique of Passivhaus