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US Energy Use and Production Homes and the Solar Decathlon, Oh My!

Housing Development Modern American Suburb

Commercial and residential buildings account for 40% of the energy consumed in the U.S. and 70% of electricity use. Renewable energy resources are well-matched to building needs. Solar heating technologies are clearly understood and have been used for decades, around the world, to heat buildings and to provide hot water. Wind power and solar photovoltaic (PV) technologies are also readily available to directly generate electricity from the sun. These energy sources are clean, reliable, and widely distributed. And yet, the energy from wind and solar resources combined account for only 0.2% of total US energy use. In fact, solar energy production in the US has actually decreased over the past 10 years.

The American West plays a prominent role in US energy issues. It is home to a treasure trove of energy resources, including coal, oil, gas, solar, wind, and water. Noting that nine of the ten fastest growing cities in the US (2000 census) are west of the Mississippi, energy consumption in the region is expected to continue increasing. With ample renewable resources and rapid growth in building energy needs, what better place to foster the development of a new future for solar home design.

The Solar Decathlon competition challenges each team to design, build, and operate their small, solar-powered home on the National Mall in Washington, D.C. Yet, the event is not really about college kids building houses on the Mall. Rather, the Solar Decathlon seeks to provide real-world training for the next generation of engineers and architects, to promote the development of innovative solutions for sustainable building design, to transfer these solutions to a diverse building industry, and to educate the public about the energy solutions available in today's market.

However, some of the constraints of the Solar Decathlon competition pose a challenge for meeting these underlying objectives. Specifically, competition rules and practical logistics dictate that these homes are small, lightweight, easy to transport, all-electric, off-grid, and completely covered with solar energy systems. Few of these competition artifacts dominate the real world. While competition rules limit the floor area to about 700 ft2 (70 m2), very few of us live in such small houses - the average new home in the US has a floor area of about 2100 ft2.

While it might be easier to design, build, and transport a 700 ft2 home for the competition, how do you make the design relevant to students, homeowners, the building industry, and the public? How do you rationalize a 7 kW photovoltaic system on a 700 ft2 home? How much bigger would the system have to be if it were in my house? How do you explain a construction cost of over $300 per square foot? How do you design appropriate thermal mass for effective passive solar heating while minimizing transportation weight? How do you develop solutions for the two million new housing units built every year by focusing on mobile homes?

Our answer? Read on...