Ultraviolet radiation (UV) from the sun passing through windows is a serious problem; however, it is not the only problem. While UV is a significant contributor to the fading of interior furnishings and artwork, the visible wavelengths of light also cause damage. Changes induced by heat gain from the visible and infrared wavelengths can create a long term problem for the integrity of artwork and furnishings, as is evident when newsprint becomes yellow and brittle, for example.Research by the Florida Solar Energy Center (www.fsec.ucf.edu) – which was done in the early 1950s to design a better glass filter to protect the original copies of the Declaration of Independence and the Constitution – found that blocking the entire UV radiation portion of the solar spectrum would not eliminate fading damage for most fabrics, but it would reduce the rate of fading by a factor of about three.Compounding the problem is that we’re using larger expanses of window areas in buildings which let in more UV and visible light, while at the same time we’re using more environmentally friendly fabrics, dyes and coatings which are less stable to light exposure and only add to problems resulting from too much sunlight.The glazing industry has tried to address the problem with laminated UV protective “museum glass” that can block almost 100% of the UV spectrum.But museum glass still allows damaging visible light and heat through to the interior of a building.
The only way to block visible light transmission in windows is to use tinted glass or glass with absorbent/reflective coatings that reduce visible light transmission. The darker the tint, the less visible light is transmitted and thus the value of the damage weighting functions can be reduced compared to a higher transmission glazing.
Dynamic glass tames both the UV and visible light spectrums, thus providing the best fading protection glazing option. Even in its clear state, some dynamic glass products like SageGlass® are more effective at fading protection than static windows such as low-e glass with similar visible light transmissions because UV blocking is integrated both within a laminate layer and as an exterior coating. In addition to blocking out most of the UV, the coatings on dynamic glass reduce heating of objects in the space and block visible wavelengths of light that contribute to fading.