Spectrally Selective Window Films

The need for energy conservation has become increasingly important over the last several decades. Several innovations have driven the growth of energy efficient glazing use in residential, commercial and automotive applications. A number of government-private joint efforts are focused on achieving even greater use of energy efficient windows [1]. Even with the high penetration of energy efficient gazing systems, a large base of existing windows will benefit from a retrofit solution. After market applied window films fit this niche very well. Several manufacturers offer a variety of window films to suit the needs of end-users. In addition to reducing passive solar gain, UV protection, low visible light reflectance and aesthetics are important to the customers. Highly reflective window films that are very efficient in reducing solar gain are popular in commercial buildings. However, in residential applications, many communities and condominiums discourage or even prohibit the use of such highly reflective films. In automotive applications, use of solar reflecting glazing can increase passenger comfort and save fuel by reducing the air conditioner workload [2]. The state laws dictate the characteristics of window films that can be used in vehicles. In general, films having high light transmission, low visible reflection and high heat rejection are preferred in many applications.