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Photo of a student holding his ear to copper tubes to hear them resonate. Some straight and some slightly bent, the tubes are grouped vertically and look like a stand of trees.

Water circulated through copper tubes, or "architecturally integrated heat exchangers," installed in the kitchen of the University of Colorado's 2007 Solar Decathlon house helps to heat and cool the home

Solar Decathlon 2007

Energy Balance

(100 points)

The Energy Balance contest requires teams to use only the energy generated by the solar electric systems (also called photovoltaic or "PV" systems) on their houses during the competition to provide all of the electricity for the contests. Teams earn full points if the energy supplied to the batteries is at least as much as the energy removed from the batteries during the competition.