Power giant TVA tests passive-solar concepts

Office complexes are often energy eaters and require massive heating and air-conditioning systems. But the Tennessee Valley Authority (TVA) is building an office structure of more than 1 million square feet which TVA officials estimate will slash traditional energy costs by 60 to 70 percent.

The key is passive solar energy.

Passive solar is a discipline that relies on building design to utilize natural heating and/or cooling. Properly placed windows, ventilation devices, overhangs, and heat-storing bricks are some of the mechanisms of passive-solar design.

Frequently, some of the myriad passive techniques are applied to take advantage of the physical properties of heat. Hot air, for example, rises and can be channeled through a building to heat it, or the hot air can be exhausted to draw cooler air through vents for cooling.

When complete, the $158 million complex will consolidate TVA's "office of power" in the heart of Chattanooga, Tenn. Currently, one TVA official explains, the 4,200 employees in the agency's administrative offices are scattered all about the city.

The new complex also will house the TVA computer center.

When the project was initiated, says Cathy Hammon, management assistant for the project, it was the nation's largest passive- solar project. "And it may still be," she adds.

Some of the nation's premier energy and solar experts designed the structure expressly for the 9-acre site, she explains, adding that passive-solar buildings require precise site orientation relative to sun and wind.

The computer center is scheduled for completion in May 1982, with the office structure targeted for December 1983. Currently, the foundation is being laid.

The project attracted so much interest before the groundwork got under way that it became the touchstone for a major redevelopment of downtown Chattanooga, says Ms. Hammon.

The project helped get support from local, state, and national officials for a $10 million federal Urban Development Action Grant (UDAG), she adds. "They made it clear," she goes on, "they would not have gotten the UDAG if we had not put the office complex on that exact spot. And now they are going after a second grant. Moreover, private industry is putting a lot of money in the area.

"It has been a closely coordinated, very active redevelopment effort."

Ms. hammon notes the distinction that the city, chamber of commerce, and legislative delegation are to be credited with the urban- renewal campaign.

Many passive techniques are being incorporated in the TVA structure.

"We will use waste heat from the computers to heat the complex," Ms. Hammon says.

Computer-controlled louvers on an atrium between the buildings will open on cold, sunny days for heat and light. The louvers will close on cold nights. In summer they adjust to provide shading and on cloudy days they will open to allow diffused light to enter. Windows, which will be operable near the ceiling of the five-story and six-story units, will allow penetration of sunlight down to reflectors which will disperse it inside.

Only two glitches have been encountered thus far, according to TVA officials. First, it is possible that Chattanooga's air-pollution problem could preclude some of the ventilation features. And second, Ms. Hammon says that plans to use ground-water cooling had to be scrapped for fear of overtaxing the aquifer.

The pollution may not be a serious problem, however, and TVA officials are designing a special heating/ventilation/air-conditioning system which is geared for energy efficiency (heavy-duty pumps and extra-capacity tanks) in keeping with project goals.

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