In Minnesota, arenas in St. Cloud, Paynesville, Austin and five other cities already use geothermal refrigeration systems to good effect. They'll be joined by a two-rink complex, the Burnsville Ice Arena, by October 2010 if all goes well.

In an arena geothermal refrigeration, the temperature-tempering qualities of the Earth are accessed. The temperature below the frost line is relatively constant, around 50 degrees. Loops of tubes are placed deep under the frost line, and a mixture of coolant and water is circulated. A heat pump extracts the heat, leaving behind a coolant cold enough to create ice for the arena.

That makes two NBA arenas in one week achieving LEED certification; Philips Arena received the same certification on the same day, although the Philips Arena information was released first.

LEED is the USGBC’s leading rating system for designing and constructing the world’s greenest, most energy-efficient, and high-performing buildings.

Philips Arena has taken a leadership role in promoting sustainability in Atlanta, and has set a new green standard nationally for arena operations and design. Its achievement represents a challenge to other venues to minimize their environmental impacts while enhancing their ability to use energy and water efficiently, to recycle, and to educate their audiences on the benefits of these actions.