In recent years, windows have undergone a technological revolution. High-performance, energy-efficient window and glazing systemsare now available that can dramatically cut energy consumption and pollution sources: they have lower heat loss, less air leakage, and warmer window surfaces that improve comfort and minimize condensation. These high-performance windows feature double or tripl e glazing, specialized transparent coatings, insulating gas sandwiched between panes, and improved frames. All of these features r educe heat transfer, thereby cutting the energy lost through windows. For the design, construction and operation of a facility,