From the Hartman Arena website:

"The building is subterranean (the seating bowl is located underground), which helps keep costs down for heating and cooling, and runs on electricity from a 150' tall wind turbine when there are no events! Recycled materials were used for the steel, insulation, and plastics in the building. New, innovative recycling ideas are in place inside the arena and carpoolers are rewarded with free parking at events."

I like this idea.