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Something old, Something New: A Gable on the Mall

October 15th, 2009 · No Comments

The University of Illinois, Urbana-Champaign (UIUC), entry into the Solar Decathlon could be called understated from the outside, a form and boarding reminiscent of 19th century barns with a stunning interior, all built to Passiv Haus standards.  The Gable House is a well-conceived residence, combining 100 year old wood boards on outside with leading edge hot water systems in a way that is easy to see becoming someone’s home. (Let’s be clear, an amazing thing about the 2009 Solar Decathlon is that everyone of the 20 solar powered homes has something to say for itself. If we took a good group of people to the Mall, it seems clear that each home would be on the top of someone’s list …)

At this time, The Gable House is standing on the top of The Solar Decathlon’s leader board, with just 10 points separating the top four teams (Illinois, Germany, California, Ontario/BC).  The last two competitions:  net metering (electrical generation) and engineering.  Illinois is a difficult situation in the first, as Team Germany has the largest solar system on The Mall but The Gable House might be drawing less power to operate its systems, perhaps closing that gap. (Gable House has 9+ kw of solar on the roof, about double their estimated requirement to run the house.) And, it is clear that the Illinois team has done a good job at engineering solutions, with innovation but also simplicity and viability. In truth, any of these four are viable candidates for top of the leaders board (with the 30+ point gap to the fifth-place Minnesota and 65 points to sixth-place Alberta make them less likely).

But, back to The Gable House …

The Illinois team is quite proud that they received their PassivHaus certification just prior to the competition. Much more widespread in Europe, a PassivHaus drives down energy demands through significant insulation, a well-sealed building envelope, and a well-engineered homes. Roughly, PassivHaus standards drive down a home’s energy usage by some 90 percent.  Gable House’s 12 inches of insulation (some R-70) is indicative of those standards.

According to team members, the heating load is so low that they were able to rise the interior temperature by 10 degrees with 10 minutes of hair dryer use. For many PassivHaus owners, the natural activities of the day (from simply human heat to cooking) are enough to heat the home in the middle of winter.

All of enables significant reductions in mechanical systems. For example, the low heating load led them away from installing a radiant heating system and, as a corollary, to decide that a solar hot water system didn’t make sense. Instead, they put in an AirTap air source heat pump for water heating, using a well insulated tank to store the water. (How well insulated?  They cut the tank off from power for three days (no, don’t know ambient air temperature) and saw the water temperature drop just seven degrees). The AirTap uses interior space air to then heat the water. A corollary benefit: cool, dehumidified air that can be used to support cooling in summer months.

Associated with the PassivHaus thinking is the simple fact that the simple screens, to support passive solar with shading while allowing in light, are moved by hand rather than automation.

One Decathlon requirement: the ability to seat 8 people (and to host a dinner party for 8).  As with several other homes, the UIUC team saw this as something to overcome, that a table for eight would overwhelm the space. Thus, for example, team members designed a coffee table that coverts to two chairs.  According to team members, all of The Gable House’s furniture was designed and built by team members.

Among other items, the framing merits mention.  Coming from Lamboo, this laminated bamboo is reported stronger than equivalent traditional wood framing and renewable.

A pleasant surprise, remarked by many, is the surprise when walking into a highly livable space, with the main living room with a bright, airy feel not suggested by the barn-like exterior.  The UIUC team is working with a modular-home builder in an effort to make this a production item, rather than simply an impressive school project.  On reflection, it isn’t hard to see how this would find a viable space in the housing market.

Additional posts on the 2009 Solar Decathlon:

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Tags: solar · solar decathlon · Solar Energy