Ennis Pyramid House
of Active and Passive Solar, Plus Wind
Lake’s Pyramid House near Ennis incorporates active and passive solar
features, along with a small wind-energy system. The distinctive
off-the-grid structure was built and furnished with an eye to energy
efficiency and conservation.
Three first floor walls and all four faces of the pyramid are made of
R-Control Panels manufactured by Big Sky Insulation of
The panels are constructed of 10.5-inch and 12.5-inch expanded polystyrene
sandwiched between two sheets of osb (oriented strand board). "They
have excellent insulation qualities, boasting an R-value of between 39.88
49 at 40 degrees," says Lake.
trombe wall on the south works by thermo-circulation. Lake explains how it
works: "Cold air falls through vents in the floor; the south-facing
concrete (painted a dark color) is heated by the sun; the warmed air rises
and is vented to the living space. Cooled air falls and begins the cycle
again." The glass front was installed by Valley Glass of Bozeman,
A Helio-Pak 16, made by Heliodyne,
Inc., is another passive solar
feature. It uses a glycol-distilled water solution that circulates via a
photovoltaic controlled pump.
"The warmth of the radiating sun does the work," says Lake.
"The heat is transferred in a loop to bring well-temperature water up
to 80-120 degrees."
He generates electricity using the sun and the wind. His solar array
includes Siemens and Kyocera photovoltaic panels that produce 1180
watts/hr during peak insolation hours.
Wind Turbine, designed to withstand
winds up to 120 mph, produces 1750 watts/hr in 35 mph winds. "The
three blades are extra stiff for severe weather resistance," says
Take an online tour of the house.
Photos courtesy of Whitney Lake.