The first Solar Decathlon, sponsored by the U.S. Department of Energy, was a showcase of solar innovation and building technology. The 14 collegiate teams used the sun to power every home appliance and to heat and cool the home — a key component of the competition.

Andrew Lee of Carnegie-Mellon University says, "Heating and cooling is typically the greatest amount of energy used in a home. That can be reduced with the right amount and type of insulation, as well as by sealing the home properly."

Some of the collegiate solar innovations showcased are:

• Auburn University's special water tanks. Part sculpture, part solar heating system, the water-filled glass tanks heat up during the day and release the heat throughout the evening.

• At the University of North Carolina house, heat pumps doubled as hot water systems. The extra heat removed by the air conditioning unit was used to heat the water.

• A special skywall panel featured in the VA Tech design insulates while allowing light to be transmitted from the outside — and without heating up like a standard window design.

• All teams used passive solar features to maximize natural sunlight, shading, airflow and ventilation and to regulate interior temperatures.

Many of these innovations are already being used in residential homebuilding. Homeowner Alden Hathaway built a net-zero colonial-style home in rural Virginia, and enthusiastically shares information with those who want to undertake the same type of project.

Alden's home contains the following innovations and solar technologies:

• 4-kilowatt amorphasilicon solar array
  
• 2-kilowatt solar monocrystalline array
  
• Solar hot water system
  
• Passive solar features/design
  
• An inverter to switch collected energy from DC to AC
  
• Is grid-tied so that extra energy collected is credited by the local utility
  
• The installation of an attic fan that will reduce overhead heat and further reduce cooling costs.