As you begin to look at what film is the right film for your needs, you will see a section named Solar Performance. So, just what do those names and numbers mean? In this article I will explain the most important ones to pay attention to when making your film choice.
Visible Light Transmission (VLT)
This spec is telling you how much light the film blocks. So, a 25% VLT is blocking 75% of the visible light. A 50% film is blocking 50% of the light or half.
Couple of reasons this spec is important to understand, this spec is used in the film to glass document because the darker the film or VLT, the more risk there is for glass/seal damage.
Total Solar Energy Rejected (TSER)
This is an important spec number, this the number that truly is the measurement for how the film performs. The TSER number is the amount of energy rejected when applied to glass, and typically the darker the film the better this number is.
For instance, a 25% film will have an average TSER of 62% to 66% depending on the manufacturer. This means that a 25% film will block an average of 64% of the total sun’s energy. Figure if you have clear glass, which blocks 5% and you apply a 25% film you are now blocking almost 70% of the sun’s energy.
Solar Heat Gain Coefficient (SHGC)
This spec measures the amount of solar heat admitted through a window. Films do this by adjusting the solar energy by reflecting, adsorbing or transmitting the energy. So, a film with a low SHGC will be very effective at regulating indoor temperatures, which in turn will reduce energy consumption to cool the structure that is filmed.
Total Solar Absorbance (TSA)
This spec is very important in determining how dark a VLT can be used in conjunction with a glass type. This is the figure used in the film to glass chart to prevent unnecessary glass fractures. The darker the VLT the higher the TSA number will be.
Visible Light Reflectance (VLR) (EXT)
This spec measures the amount of reflection the film has on the exterior (outside) of the glass. Typically a darker film will have a higher VLR to offset the absorption number and will also have a greater TSER number.
We hope this article helps you to better understand the more important film performance specifications.