SOLAR TODAY - May 2009

solar ready strategies for sustainable design

Building THE Solar-ready HOUSE

As we move toward the day when photovoltaics and solar water heating are standard

features, the high-efficiency all-electric house is a smart transition strategy.

By COLLIn TOmB

NREl

The small Habitat for Humanity house in Wheat Ridge, Colo., derives much of its heat from electric baseboards, but due to its superinsulated walls and conscientious residents, it is still a net energy producer.

More than 50 years ago, in 1953, Kansas City Power and Light unveiled its all-electric model house in Prairie Village, Kan. Equipped with the latest plastic conveniences, with all-electric heat and water heating, it promoted a life un-dirtied by the wood, gas, oil and coal burned in nearly every furnace and boiler at the time. But it suffered the irony that plagues even modern all-electric houses: Without a renewable electricity supply, they are expensive and environmentally filthy.

As we look to a future powered by renewable energy, the all-electric house is a natural solution. It pairs well with on-site photovoltaic (PV) systems and with the electric utility grid, drawing electricity from the grid and meter- ing energy back from rooftop PV when it’s sunny. The catch is that without renewable energy, an all-electric house is running on electricity produced to a large extent from fossil fuels, depending on where you live.

DAN FRuEH PHOTOGRAPHy

Generating energy from on-site sun resources makes more sense than ever as PV prices continue to drop and incentives increase. Offsetting even a portion of electricity needs with PV can have significant benefits. Yet for builders and architects that have yet to make renewable energy features standard because of cost concerns, offering all-electric houses with solar-ready features is a good interim strategy. The problem is that the 1950s descendents of the first all-electric house, without renewable energy supply, can now cost twice as much to operate as their natural gas-powered

Collin Tomb is an architect and writer in Boulder, Colo., specializing in carbon-neutral design and energy retrofit. Patrick Hughes, director of the Building Technology Research and Integration Center at Oak Ridge national Laboratory, contributed to this article with expertise on heat pumps. Technical assistance was also provided by Walter Grondzik, architectural engineer and professor in the Department of Architecture at Ball State University.