Hybrid house built by Poewel Gelderloos in Emigrant, Mont. Power produced by the home's renewable energy systems is stored in direct current storage batteries adn converted to 120-volt alternating current for household use.

By Derrill Holly | This article is reprinted with permission from ECT.coop.

A Montana homebuilder has constructed a “hybrid house” using energy-efficient design features and renewable energy technology to keep his electric bills from Park County Electric Cooperative down.

“When the sun shines and the wind blows, I’m generating electricity that I don’t even use,” said Poewel Gelderloos, who moved into his Emigrant, Mont., house in March.

Features including a 5-kilowatt roof-mounted photovoltaic solar array and 2-kilowatt wind turbine have supplied far more power than he and his family can use.

Park Electric Cooperative currently has 13 members with renewable energy interconnections; of those, seven are “net-metered,” allowing those members to receive credit for energy put back on the grid.

Douglas Hardy, the co-op’s general manager, observed that “A lot of what [Gelderloos] has done is experimental and he’s seeing how it’s going to work.”  Some of the features will be more cost-efficient than others, an important factor for most cooperative members, says Hardy.

Radiant heat coils installed in the subflooring, 14-inch thick walls with an insulation value of R-45 and double-paned windows make efficient use of the propane heat, and make electricity from the co-op optional under most weather conditions.

Sharply pitched rooflines and oversized gutters take advantage of the area’s 16 inches of annual rainfall and prolonged snowmelt. Holding tanks buried beneath the home hold up to 10,000 gallons of water, collected and filtered for household use.

So-called “gray water” from laundry or bathing is refiltered for irrigation in the home’s attached sunroom-greenhouse. Wastewater from the kitchen sink and toilets flows into a conventional septic tank.

A pair of mini-computers will determine when a propane burner should kick on to supplement the solar-heated water supply or draw power from the grid, but so far no co-op electricity has been needed.

Park Electric Cooperative has longed preached on the benefits of energy efficiency to its members.  When the local ground source heat pump installer (whose business Park Electric helped launch) moved to the other side of the state, the cooperative shifted its focus, encouraging members to consider air source heat pumps with a propane back up. 

Since March, his bill from Park Electric Cooperative, Livingston, has averaged $45 a month, largely for a small cabin on his property that’s unserved by the systems included in construction of what he calls his “Oasis House.” The house is designed so that natural resources are used first and when they get low, conventional systems kick in.

Gelderloos spent $500,000 on the house.