are frequently referred to as “solar control” window films. However, there is a great deal of confusion and misunderstanding about ‘solar energy rejection,’ particularly in the infrared range.
is a form of electromagnetic radiation. All forms of solar energy can be expressed as a wavelength, which is the measure of the length of a full cycle in a repeating electromagnetic curve.
The solar energy that enters into the earth’s atmosphere is split into three bands by wavelengths; the ultraviolet (UV), visible light (VL) and infrared (IR) bands.
The UV Band
is measured between 100-400 Nanometers and are the wavelengths most responsible for fading or sun damage to carpets, drapes, fabrics, upholstery, etc. The UV band is the one that tans the skin and can also contribute to certain types of medical problems when over exposed, such as certain types of skin cancers. The UV band accounts for 3% of the solar spectrum.
The VL Band
is measured from 380-780 Nanometers. This is the only part of the solar spectrum actually seen with our eyes and is the most intense in the entire solar spectrum. The visible light band accounts for 44% of the solar spectrum.
The IR Band
is measured from 780-50,000 Nanometers and is divided into the near infrared (NIR) and the far infrared (FIR) bands. Infrared accounts for 53% of the solar spectrum.
is measured from 780-2400 Nanometers and is the ‘heat band’. We do not see it, but are aware of it and sense these wavelengths as heat. The NIR band accounts for only about 3.2% of the entire infrared range.
is measured from 2400 to 50,000 Nanometers. This band is beyond the NIR and accounts for 96.8% of the total infrared band. There is no solar energy in the FIR band. The far infrared band has nothing to do with solar heat gain but is crucial in containing heat loss.