At about 450,000 sq ft, with anywhere from 45- to 55-ft ceilings, the facility is large enough to have its own climate - or three separate climates, as Chicago director of building operations Dan Carey pointed out. "Along the perimeter of the building where we have 10 heating units, the ambient temperature is comfortable, but that wasn't the case as you got into the center of the building."
There, said Carey, temperatures could be as low as 55 degrees F on any given winter day. The units did a great job of heating a 20-ft radius, but after that, the heat soon rose to the ceiling, where temperatures reached 95 degrees. From there, rooftop exhaust fans vented the heat to the outside. "Energy efficiency was a problem, and so was employee comfort. We knew we needed to fix the problem."