It’s big: 2,048 bunks and 21 buildings. It’s expensive: $254 million. But it saves a lot of energy. Since the extension of Coyote Ridge was completed in October 2008, the penitentiary uses 5.5 million fewer gallons of water than similarly sized prisons, while saving close to $400,000 a year, according to The Independent. The buildings of Coyote Ridge collectively save power by using state-of-the-art, tall and skinny windows that keep prison cells cool in summer and retain heat in winter. The combination of green windows, energy-efficient boilers and an efficient ventilation system has reduced the prison’s energy usage by 50 percent.