Fifteen window and glass manufacturers were told in August to review their marketing material for possible violations of the FTC Act, which prohibits unsubstantiated energy-savings claims, the FTC said. The businesses are making claims similar to those made by five replacement-windows businesses that settled with the commission this year over their allegedly "exaggerated and unsupported claims" of energy-efficiency and energy-cost savings, the FTC said. Cardinal Glass Industries in Eden Prairie, which claims that use of its window glass "can reduce your energy bills by one-third," has the data to prove its claims, according to Cardinal vice president Bowie Neumayer. "We'll review what we do state and send in the data to back it up," Neumayer said. Read the FTC's warning here.