Seasonal Equipment Beats Permanent's Payback

What began as a one-time summer rental is moving into its sixth season. In 1996, Toyota Motor Manufacturing in Georgetown, Ky., began renting chillers to maintain its assembly plant at 79°F. Five air-cooled chillers with a total 1,500 tons of capacity took the heat and humidity out of the ambient summer air.

Eventually plant managers undertook an analysis, the results of which showed that using the rental chillers for peak summer loads was more cost-effective than adding to the 25,000-ton permanent water-cooled chiller capacity.

With 7,800 team members working on two shifts five days per week, "we performed load calculations using the most current weather patterns, and determined that we would need an additional 2,500 tons of chiller capacity," says Gary Van Corp, a mechanical specialist for Toyota. "By using air-cooled rental chillers, we eliminated the need for adding cooling-water piping connections and temporary containment areas for a water-cooled system."

For three years, the company rented seven 2,500-ton chillers. Then, Toyota added 2,000 tons of permanent chiller capacity, but still rented five 300-ton-capacity units in 1999 and 2000. The annual rental period runs from mid-June through August, the time of peak summer power loads.

From Pure Power, Summer 2001.