Fairbanks Daily News-Miner, Sam Harrel) **MAGS OUT NO SALES**, Associated Press
FAIRBANKS, Alaska — Karl Kassel fell in love with the site while ptarmigan hunting in 1975. At the top of Murphy Dome, his octagonal wood house overlooks Denali and Murphy Dome Valley. It was 2 below zero outside and 70 degrees inside when he woke up on a recent Wednesday. He hadn't heated the home for three days.
Energy from his windows, solar photovoltaic panels, wind turbine and solar thermal panels was being stashed for next winter.
"If it stays sunny for the next several days, we'll probably not have to light the fire again until October," he said.
Kassel, his wife Billie and their 15-year-old son moved into the off-the-grid house last January.
"It's crazy the amount of energy that's available here in Fairbanks, that we waste," said Kassel, who had been dreaming up the house since the 1970s. "I finally said, 'I'm going to do this. It makes sense, the energy's available, the efficient designs are here. We know how to do this. Why aren't we?'"
So Kassel hired Thorsten Chlupp, general contractor and owner of Reina LLC, to build a highly efficient home that made the most of the area's resources. They designed a house that combines passive solar design, renewable technologies and energy storage to make the variable sunlight in Fairbanks last almost the whole year. They are studying its performance to make the design more efficient, less expensive and less dependent on fossil fuels.
The southern side of Kassel's 1,800-square-foot house is mostly windows, letting in every drop of available sunlight.
The octagon is 20 percent more efficient than a square design because it has a lower surface-to-volume ratio and softer corners, which is where you lose the most heat, Chlupp said.
It was just as warm in the shadowed arctic entryway as by the sunny window.
"You don't have any loss, you don't have any drafts," Chlupp said. "You can feel very comfortable in a house like this at 64, 66 degrees."
The interior has an outdoors theme with tree sculptures, a free-form island in the kitchen and locally made birch cabinets with hand-picked rock handles. The house contains 16 tons of rock collected from river trips and a rock party. A blue river flows through sandy banks on the stained concrete floor and the living room is trimmed with plant beds containing two tons of dirt.
"We like being outside and floating rivers," Kassel said. "So we designed the house to be like camping on a gravel bar."
All of these items, plus nearly 13,000 gallons of hot water, are designed to absorb and save the maximum amount of heat.
The heating system focuses on saving energy in the water tank for later use. Heat travels, via glycol, from solar thermal panels into loops in the floor and a 120-gallon domestic hot water tank in a closet. When Kassel starts a fire, coils in the masonry heater carry heat into the water tank. When the indoor tank hits 140 degrees, it diverts extra heat through a heat exchanger to a 12,000-gallon tank buried outside.
The electricity generated by a 1.6-kilowatt solar array and 3-kilowatt wind turbine first powers the refrigerator, water pumps and other utility needs. The system was producing 400 watts Wednesday afternoon and the house, with lights on, was only using 290. The extra power charged a battery bank sitting in the closet, which stores about three days worth of power, Kassel said.
Once the battery is full, wind and solar are channeled into an electric heating element to heat the water tank.
"The PV panels are awesome," Kassel said. "They operate more efficiently in cold weather, and you get double sunlight because of the reflectivity off the snow."
The wind is also a surprisingly steady resource, he said.
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