In winter, concrete and gravel floors serve as a heat sink, while heat-recovery units pull warm exhaust air from the conditioned spaces. In summer, louvered openings in the glass structure's lower quadrants bring in cool air, while warm air is expelled through roof vents. There is no air conditioning. Rainwater collected from the roof is used to clean the roof, flush toilets and water lawns. Two cogeneration plant modules use methane gas released from former mining shafts on site to create additional electricity and heat.
Surplus electricity is fed back to the utility grid.
In arid climates with clear night skies and cool night temperatures, water chilled on rooftops overnight can cool building interiors the next day. In such climates, roofs radiate heat outward to the night sky. By midnight, most low-slope roofs are cooler than the outdoor air. Night roof spray systems, such as NightSky by Integrated Comfort, Inc. of Davis, California, chill water to 50 to 55 degrees at night by spraying it over large, low-slope roofs. The chilled water is captured at roof drains, filtered and stored.