When we visited the Leitz household a year ago, it was brand new, and the family was just starting to learn how it would work. Now they're all moved in, and delighted with the comfort of the house. Today, Curt Leitz is barefoot. He and his daughter are wearing t-shirts, while outside it's a windy 12 degrees.
It's 74 degrees inside the house. On long northern Minnesota nights, the temperature cools off a bit.
"Overnight, even without any additional heat being put into the home, it dropped only to about 64 because of the amount of insulation that we have here," Leitz says.
The house is perched on a hillside overlooking Lake Superior. Its triple-glazed windows face south toward Lake Superior to collect the sun and the walls are packed with 14-inches of insulation, that's twice as much insulation as most houses built these days.
Downstairs there's a dark-colored concrete floor and a concrete wall that absorb the sun's heat in the daytime and let it out at night.
Upstairs, the sun pours through the windows onto the hardwood floor.
If it's cloudy for a couple of days, water in a big tank in the basement heats the house through pipes that run under the floors. The water is warmed by a solar collector on the roof.
"Now, if we have a string of cloudy days and cold temperatures, as we had earlier this month, and the water is not warm enough to heat the house, then we have a very small instantaneous gas-fired hot water heater as a backup, and we also have a small wood stove up here as backup," says Leitz.
But that gas-fired water heater doesn't come on much.
Over the course of the year the Leitzes have paid an average of $33 a month for gas. That compares to the average Duluth resident whose monthly gas bill was $138 -- four times as much.
"I just checked the gas meter outside, and for the month of December, which we would expect to be our worst months -- it's been a very cold December and it's been typically very cloudy as well -- we've burned $63 worth of gas in the month of December," Leitz says.
That cost includes gas for a clothes dryer and kitchen stove.
The Leitzes use about half the electricity as the average Minnesota household, too.
Leitz goes down to the basement to check out his hot water storage tanks at least once a day. He's like a hyper-miler, one of those Prius drivers who squeezes as much energy as possible from his car by driving extra-carefully. Leitz squeezes more energy from the sun by adjusting when he does laundry or runs the dishwasher.
"I might come down here and if the water tank is below the temperature that I need water at, and it's sunny, I'll just wait six or eight hours, and then use free energy," says Leitz.
The house stays comfortable in the summer too. The sun is higher in the sky, and wooden trellises over the windows keep it from shining in. The breezes off Lake Superior help, but Curt Leitz says if it got really hot, he would close the windows and the insulation would keep the house cooler.
The architect who helped design the house, Doug Zaun, says more and more people want to build energy-efficient homes. It only costs 10-to-15 percent more than standard construction to get the dramatic energy savings the Leitzes have achieved, he says. But he admits it can be hard for families building a house to find the money to do so.
He tells his clients they should put a high priority on what he calls the building envelope: the insulation and the south-facing orientation. They can make other improvements later.
"Perhaps instead of buying $10,000 countertops, they start with $2,000 countertops, take that $8,000 and add it to more insulation," Zaun suggests. "Ten years from now, when they need new countertops they can make that upgrade."
Or, they can use their energy savings to pay for a bigger mortgage.
"Curt's maybe saving a couple hundred dollars a month, so he can afford a mortgage that's a couple hundred dollars more, and that can buy a lot of insulation and better windows," says Zaun.
Of course, it's harder to do on existing homes.
But people can incorporate energy savings into their home through smart maintenance projects, Zuan says. If they need to replace siding they can add insulation, or if they need to replace windows they can buy highly efficient ones.
The Skyline House was one of the attractions during the North American Passive House Conference, held in Duluth last fall. Curt Leitz is happy to show it off. But he hopes one day it won t be quite so unique.
"Ultimately our goal is for this house not to be remarkable and exceptional but to be the norm or even a bit retrograde," says Leitz. "We'll know that we've succeeded when there's no more attention on this house because it's so usual."