A. Not necessarily, says UW-Madison biological systems engineering professor and building design expert David Bohnhoff. Inside any well-insulated building with good air circulation, the temperature between floor and ceiling usually only differs by a couple of degrees -- even when the building is a cavernous store.

In a structure with a poorly insulated roof, on the other hand, heat will always rise and escape, no matter how low or high the ceiling is.

Ceiling height plays a relatively small role in heat loss for another reason: Tall walls tend to have the same window area as shorter walls. "Note that windows are the big energy losers," says Bohnhoff. "So as long as you don't add windows when you increase wall height, the added tallness shouldn't be a major concern."

Still, why have such high ceilings in the first place? Lowering a ceiling to the height of shelving makes it harder to operate forklifts and other equipment, says Bohnhoff, or to achieve uniform lighting, proper ventilation and adequate water sprinkling for fire protection. "You also begin to restrict future expansion and use of the building," he adds.

High ceilings do have a downside, however. Increasing a building's heated space may also increase the volume of air that needs to be exchanged every hour with the outside, says Bohnhoff. Warming the incoming air can get expensive, unless an air-to-air heat exchanger is used to recover energy from the outgoing air.

-- Produced in cooperation with University Communications

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