Trane

These systems pair chillers or heat pumps with storage tanks and controls. A building makes ice or banks heat during off-peak hours, then draws on it for cooling or heating when electricity costs more. Trane also sells building controls, maintenance and energy services.

Trane says it has more than 100 years of experience. It worked with the California State Lottery on a headquarters project using ice-based storage that, by Trane's account, cut peak-hour cooling costs by 21 percent.