Hurd. The company’s new Ultra-R glass option with Heat Mirror technology utilizes film suspended in insulated glass to achieve R-values up to R-20 (when filled with krypton gas). The film, made by Southwall Insulating Glass, is coated with nanoscale metal particles that reflect heat back to its source and improve insulation, block UV rays, and reduce noise, the company says. The lightweight windows come with up to three sheets of virtually weightless film to create up to four super-insulating cavities. 800.433.4873. www.hurd.com.