D e s e r t E x p o s u r e
April
2009
Zero Energy House
Page: 2
After a tour of the first-floor kitchen, bedroom and bathroom, Austin leads the way up the bamboo-covered steps to the second floor, which holds the master bedroom and bath. All the bathrooms, he points out, boast dual-flush toilets, which save thousands of gallons per year by better matching their flushing power to the need. The second zero-energy house they've built will further save water by using rainwater in the toilets. (Here, rainwater also gets collected, but only for outside watering use.)
The balcony off the master bedroom gives a view of the house's off-street parking, which features plug-ins where a future owner could juice up his hybrid cars. "You could fill your gas tank off the roof," Austin says with a smile.
That's because the house sports 16 photovoltaic solar panels, totaling 2.1 kilowatts of electricity-generating capacity. Actually, however, Austin's using poetic license with the notion of powering hybrid cars straight from the house: Lizard Stone has taken advantage of the house's in-town location, on the power grid, and avoided the need for bulky, expensive batteries to store solar-generated electricity. Instead, the house simply uses conventional power from the electric grid, while selling its own solar power to PNM at a premium retail rate. The difference between power purchased from PNM and power sold back to the utility, Austin figures, ought to net the homeowner $50 to $75 a month.
"There's a tremendous excess during the day," he says. "In effect, we're storing our power in the grid."
The balcony also overlooks the flat, rectangular panel of the passive-solar water heater. But to really understand how that works, Austin says, you have to go down to the walkout basement — clearly his favorite part of the house.
Downstairs, Austin gives a brief tour of what could be a third bedroom or a home office (especially since it has its own entrance), plus another bathroom. Then he leads the way into the utility room, home to not one but two hot-water tanks and a neat nest of black tubing and red-rimmed dials.
"I like this part a lot," Austin confesses.
Again, the notion of a solar water heater is a bit inaccurate, as what
the sun striking the roof actually heats is ethylene glycol — the same
substance used in antifreeze. That way, what gets pumped up to the roof for
warming during cold weather doesn't freeze before the sun hits it. From the
passive-solar panel, heated glycol circulates down to the first tank — really
just used as a holding tank — where the heat gets exchanged from the
glycol to water. The warmed water then flows to the second tank, a commercial-grade
Polaris hot-water heater. When the sun is really shining, the Polaris doesn't
have to work at all to get the water up to temperature.
From the second tank, that complex of tubes and dials sends hot water into a continuous loop throughout the floors, providing radiant heating. When you want to take a shower, the same system provides instant hot water — no waiting. In summer, the tubes in the flooring carry water straight from the city's underground pipes, cooling the slab instead of warming it.
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Mark Austin shows off the hydronic
radiant heating system. |
The combination of radiant heating — rather than forced-air heat from a furnace — and the passive-solar warming of the walls and floors enables the house to have that soaring ceiling in the living room. "Air is a great insulator, but it doesn't actually conduct heat very well," Austin explains. "The mass of the house is what's warm. That's why we don't care about high ceilings. We don't have to care about our air."
The utility room also houses the inverter that turns 360 DC power into 120 AC power for selling back to PNM. Austin shows it off like a proud papa.
Despite all the house's innovations, though, Lizard Stone has had to make some compromises. Stepping out the downstairs walkout, for example, you can see pressure-treated lumber. "There's OSB in the house," Austin allows, referring to "oriented-strand board," an engineered wood product manufactured with waterproof, heat-cured adhesives. "It's required by code. Wherever wood touches concrete, you have to use treated lumber.
"We've tried to do our best possible work and still have a house that can actually be created. So, yeah, there's a framed floor. Still," he pauses, tugs thoughtfully at a curling lock, "this is pretty damn green."
Someday, however, Austin and Clements hope that houses like the one on West Street won't seem all that unusual. The house has been a work-in-progress, an experiment, but the lessons learned should pay off in a greener future.
"We've tried to be open-minded," Austin says. "Our attitude has been, 'Let's try something different.' If there's a new product out there, we'll take a look. It's way too easy to just keep using the same old inefficient technologies."
He fingers the blacksmith-crafted handle of the back door. "Certainly, we're not getting rich doing this. We're doing it because we care. We think this should be normal. We hope that 10 or 20 years from now, none of this will be special."
For information on Lizard Stone Builders, call 538-1233 or 519-9947, email info@lizardstonebuilders.com, or visit www.lizardstonebuilders.com
David A. Fryxell is editor of Desert Exposure.