Those oh-so-soft and “natural” bamboo sheets you bought a few years ago may not have been made of 100 percent bamboo fibers after all. The windows that promised to lower your heating bill by hundreds of dollars may not save you much at all.

Misleading claims for these products, as well as low-fume paints, have been targeted by the Federal Trade Commission in its continuing battle against companies trying to gain ­environment-minded customers with dubious “green” pitches.

Last week the FTC released its yearly accountability report that showed the agency had succeeded in reducing the number of inflated or false energy-cost saving claims made by window companies since 2009. The agency does not know yet whether it made similar progress in stopping false bamboo fabric and non-VOC (volatile organic compound) paint claims.

Laura DeMartino, chief of staff at the FTC’s Bureau of Consumer Protection, told Whistleblower that in recent years, the commission has sent dozens of warning letters and taken several companies to court for making false claims of “green” products.

In 2012, the FTC identified 29 websites that it said made deceptive energy and cost-saving claims. It fined five of the largest firms. The agency sent warning letters to 15 others that it said were still making the false claims. One of them was Cardinal Glass Industries, an Eden Prairie window manufacturer.

“We reviewed your website, and found claims similar to those challenged in recent FTC lawsuits,” the FTC wrote in August 2012. The company claimed that a type of glass could “help save a bundle. In fact, you can reduce your energy bills by one-third by simply using low-emissivity glass,” according to the FTC letter.

Cardinal Glass has since removed that language from its website, and the FTC took no further action. A representative of Cardinal Glass declined to comment Friday.

St. Paul’s Window World has not been targeted by the FTC, and owner Terry Derosier said he would never make money-saving claims because replacing windows can never guarantee lower energy bills.

“Houses that are older can have really leaky windows,” Derosier said. “But the attic may be the major area of leakage, and you may have to insulate that properly.”

While some window companies claim to save you money, companies trying to sell you “green” bamboo ­fabric may just be ripping you off.

Legitimate bamboo fabric is not even available commercially at this time, according to an attorney with the FTC. ­Bamboo fabric may be used in manufacturing, but once it’s processed, it becomes rayon, which is made “using toxic chemicals in a process that releases pollutants into the air,” an FTC consumer warning said.

“Bamboo fabric has short fibers, so it’s a much tougher texture,” said FTC staff attorney Korin Felix. “That’s why it would be really unlikely to find undergarments and sheets made out of bamboo.”

Whistleblower’s quick online search for bamboo sheets produced a host of sites that still sell them. Some sheets are advertised as “100 percent rayon from bamboo” or “viscose bamboo” which is not a false claim. But a sheet set on Amazon advertised itself with, “wrap yourself in the softness of the luxurious 100% silky bamboo sheets and save the planet while you sleep!”

Amazon was one of the companies that the FTC fined in January for continuing to advertise their products as made of bamboo, despite warning letters from the agency ­saying it was misleading. Macy’s, Leon Max and Sears also were fined hundreds of thousands of dollars.

Sears advertised sheet sets in its stores and on its website as “pure fiber 100% bamboo,” and sold a “Ty Pennington Style Bamboo Sheet set” that it claimed was made of 55 percent bamboo and 45 percent cotton.

Felix said that it’s not impossible to make legitimate bamboo fabric and in the future, it may become a common textile. The agency has not had any concerns with advertisements for bamboo that is sold as a wooden product, such as floors. 612-673-4028