DALLAS, TX - It was a hot time in Texas. During the summers of 1998 and 1999, record-breaking heat in this city forced building operators to crank up their air conditioning systems - sometimes for 24 hrs a day.

In 1998, with 56 days of temperatures at 100°F or more, it's not surprising that utility bills ran 15% to 35% higher than most summers. But at the headquarters of Central & South West Corporation (CSW), building services technician David Lewis reported a significant decrease in energy usage.