The Federal Trade Commission has accused Aluminum Co. of America of making false claims about the value of aluminum siding as a home insulator.

In a complaint against the aluminum company and its subsidiary, Alcoa Building Products Inc., that could affect the entire siding industry, the agency asserted that "plain aluminum siding installed over aluminum foil has little or no insulation value" for existing houses and won't produce any significant reduction in fuel costs. Even insulated aluminum siding set in place by accepted installation methods "frequently provides no or little insulation value," the FTC contended.

At the same time that it announced the complaint, the FTC said that Alcoa and its subsidiary had settled with the commission by consenting to an FTC order that bars them from making any further claims about the thermal-insulation energy savings or fuelreduction benefits from use of Alcoa aluminum siding. However Alcoa's acceptance of the order doesn't represent an admission of the violations alleged against Alcoa in the complaint, the commission said.

The FTC cited a number of "false, misleading and deceptive" statements that it said the Pittsburgh-based company used in its advertisements and other printed materials for aluminum siding. One was the claim that "when properly applied over relfective aluminum foil in your present exterior siding, Alcoa siding forms a protective insulating envelope that could reduce heat loss in winter and heat gain in summer. And save precious fuel."

Alcoa didn't respond to requests for information about the consent order. However Stewart Spector, an aluminum industry analyst for Openheimer Inc., said the consent order won't have much impact on Alcoa's sale of aluminum siding coil to fabricators, who turn the coil into the actual product that goes on houses, is a small part of Alcoa's total business. Further, he said that aluminum siding is sold for its ease or maintenance rather than its insulating qualities, so the total impact of the consent order on Alcoa's business is likely to be "insignificant."

Spector said two other companies -- Alcan Aluminum Corp., Cleveland, and Reynolds Metals Co., Richmond -- sell finished aluminum siding, and he said total shipments of siding amounted to less than 4 percent of aluminum industry shipments last year.