These aluminum-clad wood windows are the company’s most energy-efficient offering, and the only wood windows available with triple-paned glass. Advanced low-E triple insulating glass with argon blocks up to 97 percent of the sun’s ultraviolet rays; some operable units in this series have a u-factor as low as 0.25. Between-the-glass blinds, shades, decorative panels, and grilles snap in and out via a proprietary hinged glass panel, for a wide range of design possibilities.