Johnson Window Films Dealer Resource Center

JWF Film Facts, Solar Radiation

The sun is a major source of radiant energy. As discussed in the solar radiation home page, this energy travels in waves until it reaches earth. It is broken down into 3 types
of energy sources, known as the Solar Spectrum, which includes infrared rays, visible
light and Ultraviolet (UV) rays.

Here is a breakdown of the 3 solar spectrum energy components:

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1. Infrared Rays (53% of solar spectrum)
feel as heat measuring above 780 nanometers

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2. Visible Light (44% of solar spectrum)
visible band you can see between roughly
380-780 nanometers

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3. Ultraviolet Rays (3% of solar spectrum)
invisible heat ranging from 100-380 nanometers

Now that we understand what solar radiation is and how it is measured, let’s take a look
at the 3 things that can happen when solar radiation finally reaches a glass window.

1. Energy passes through the glass.
2. Energy is reflected away from the glass.
3. Energy is absorbed within the glass.

Therefore, total solar energy is either reflected, transmitted or absorbed. These actions are always expressed in percentages that will always total 100%.
For a 1/8-inch glass window without window film, the percentages can be broken down as follows:
(see diagram to the left)

Total Solar Transmittance: 89%
Total Solar Reflectance: 6%
Total Solar Absorption: 5%
Total Solar Energy: 100%

Looking at the energy balance that occurs on an untreated piece of glass, it's obvious that a very high percentage of solar radiation (infrared, visible light, UV) is transmitted through the glass while only a small amount of energy is reflected or absorbed. When window film is applied to glass, these percentages will shift accordingly as more total solar energy is reflected and absorbed, while less energy is transmitted.
(see diagram below)

Total Solar Transmittance: 29%
Total Solar Reflectance: 38%
Total Solar Absorption: 33%
Total Solar Energy: 100%
Example is of Solar Silver 35 (SS35) film

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