This measures how much light comes through a product. The visible transmittance is an optical property that indicates the amount of visible light transmitted. VT is expressed as a number between 0 and 1. The higher the VT, the more visible light that is transmitted. Dark tinted coatings can significantly reduce visible transmittance, but it is possible to get windows with high VT (about 0.70 for the glass or 0.50 for the whole window is best for maximum daylight and view) and low SHGC—greater amounts of light with less solar heat gain.

Additional Resources

UF IFAS Energy Efficient Homes: Windows and Skylights - http://edis.ifas.ufl.edu/FY1045

 Building a Safer Florida, Inc., University of Florida's Program for Resource Efficient Communities, and the Florida Department of Community Affairs. May 2006. Window Systems http://www.dca.state.fl.us/fbc/publications/Fact_Sheets_0307/WindowSystems061506revised.pdf

 Efficient Windows Collaborative. September 2007. Fact Sheet: Selecting Energy Efficient Windows in Florida. http://www.efficientwindows.org/factsheets/florida.pdf