Built with 20 prefabricated panels made by a company in North Carolina, the house includes a number of green features, beginning with the shape itself. The round design gives the home an improved surface-to-volume ratio 鈥� and consequently, improved energy efficiency 鈥� over a standard, boxy house. Simple ways the Kennels maximize the efficiency of their house: passive solar design, orienting the house to maximize and minimize the effect of sunlight at the appropriate times of year, thick insulation, reflective roof shingles, well-built windows and doors, and 鈥渨indow quilts鈥� to minimize heat loss.

The house also includes some higher-tech green features, including solar collectors to heat the house via radiant floor heat and the water system (on March 1, a sunny but chilly day, their tank temperature reached 120 degrees). A separate, 4.8 kW photovoltaic system at the house generates about half the electricity the couple uses.

Elmer鈥檚 and Marianne鈥檚 previous house, built in 1980, also had solar collectors for hot water and a passive solar design.

鈥淚t seemed like the right thing to do years ago, and it still is,鈥� says Elmer, who retired in 2010 from his career as a general surgeon affiliated with Rockingham Memorial Hospital.