Southwest Solar

Past and present combine in architect Michael Frerking’s new energy-efficient house in Prescott, Arizona. Like the cliff dwellings of Canyon de Chelly or Mesa Verde, this house burrows into a hillside, using the surrounding earth as insulation against extreme heat and cold. The windows are oriented so low-angled winter sun can penetrate deeply and be absorbed by the floors and walls; this stored heat is radiated at night. A well-insulated roof shades the interior from the sun in the summer.

But this house, which Frerking constructed with the help of builder Darren Haenny, also incorporates the latest developments in green building technology. “We intend to reach ‘zero load’ (instead of drawing from municipal sources) for heating, cooling, and water use,” says Frerking. Indeed, the house uses the sun not only for passive warming but also for electricity, thanks to an array of photovoltaic panels mounted on the roof. Rainwater is harvested from roof runoff and stored in a 10,000-gallon cistern for cooling and heating, as well as landscaping. 

The key innovations

Poured-earth walls create a patterned effect and add insulation. The multihued layers of earth turn the stair wall into a natural mural. 

The well-insulated roof is supported on ready-made curving laminated beams. The lower section, which extends into the interior, has galvanized metal roofing and an interior light shelf that reflect low-angle winter sunlight onto the curving ceiling and deep into the living space.

The 3-kilowatt photovoltaic array is tied into the electric company’s grid, allowing Frerking to sell excess solar-generated energy to the local utility.

An attached sun space on the lower level collects heat for growing fresh vegetables, while heating the main floor mass from below.

A heat-recovery ventilator mixes outside air with captured heat or cool air, so fresh air is provided without compromising energy efficiency.

Native and drought-tolerant plants are used for landscaping.

Low-cost precast concrete tiles are set in sand over a standard membrane roof to create exterior decks. 

Design:  Michael Frerking, Living Systems Sustainable Architecture, Prescott, AZ (www.michaelfrerking.com or 928/717-2566)

Construction: Darren Haenny, Wolf Environmental, Sedona, AZ (www.wolfenvironmental.com or 602/526-1299); Royce Carlson, Cosmic Steel, Prescott (www.zenzibar.com/cosmicsteel or 928/445-3831)