COOL N LiTE® ’s range of metallic and sputtered – based window films are quality products of a technologically advanced breakthrough, setting new standards in comfort, security and aesthetics of every modern automotive, home and office.
In this section, terminologies and technologies applied in the development of high-tech solar control films are explained. Our films are specially treated to spectrally filter relevant wavelengths of solar energy (from the sun) to provide maximum visible light transmission while reducing harmful UV rays and IR radiation to a minimum.
UNDERSTANDING SOLAR ENERGY
Solar energy 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 (VIS) and infrared (IR) bands.
Their intensities vary depending on their wavelength size and each one accounts for varying percentages of heat as indicated in the following diagram.
High Tech Solar Films act as a filter reducing varying percentages of each part of the Solar Spectrum. Darker films will filter out more visible light resulting in energy reduction whereas lighter films have to filter out more infrared in order to reject large amounts of energy.
TOTAL SOLAR ENERGY REJECTION
Films can be designed to work on either one part of the Solar Spectrum or all three. Clearly then when we read the specification called “Total Solar Energy Rejection”, we can now see that it is not referring to temperature reduction percentage, but rather, it is the percentage of incident solar energy rejected.
The Total Solar Energy (TSER) specification along with another specification that is commonly used in the glass industry called the “Solar Heat Gain Coefficient” (SHGC) are two excellent ways for consumers to compare the performance of one window film to another.
(UV) ULTRAVIOLET RADIATION
Ultraviolet radiation is measured between 100 to 400 Nanometers and accounts for about 3% of the total solar spectrum. Despite the small percentage of the total solar energy, ultraviolet radiation plays an important role in both the energy balance and chemical composition on earth, including the production of vitamin D in humans. However, there are some serious negative effects of ultraviolet radiation as well. Ultraviolet rays are commonly associated with fading or sun damage to all types of interior furnishings, such as carpets, draperies, upholstery and furniture, etc.
In addition, UV rays tan the skin but are also directly related to various types of skin disorders, cancers and eye problems such as cataracts. While it is virtually impossible to completely avoid all contact with ultraviolet radiation, there are preventative steps that can be taken to reduce or minimize the risks of overexposure, such as wearing long and closely woven clothing, proper sunglasses, wide brim hats and sun-screens with a sunprotection factor (SPF) of 15 or higher on all exposed skin.
In most cases, standard plate glass or automotive glass is fairly efficient in preventing UVB radiation from passing through it, which is why it is difficult to get a sun tan behind glass. However, a very high percentage of the UVA radiation still penetrates standard glass and can significantly contribute to skin problems.
Measured between 320 to 400 Nanometers, is about 1,000 times less in intensity than UVB rays but between ten to one hundred times more prevalent in the earth’s atmosphere. UVA are the longest of the ultraviolet wavelengths and therefore passes through material objects, including glass, far easier than the other UV rays. UVA also penetrates skin more deeply than the other UV wavelengths and interacts with organic molecules, which promotes the development of various types of skin cancers.
Measured between 290 to 320 Nanometers, are the wavelengths most responsible for causing a reddening of the skin or sunburn, as well as “welder’s flash” and “snow-blindness” which are irritations of the cornea caused by overexposure to excessive light.
Measured between 10 to 290 Nanometers, are the shortest UV wavelengths and potentially the most lethal to human life. Fortunately, virtually all of the UVC radiation is blocked out by the earth’s atmosphere, primarily the ozone layer, before it reaches the earth’s surface.
PROTECT YOURSELF FROM HARMFUL UV RAYS
Installing window film may be an important precautionary step in reducing the risks of overexposure to ultraviolet radiation. All COOL N LiTE® professional quality window film is produced with full body dyed, weatherable polyester, with additional UV inhibitors in the mounting adhesive.
Many films on the world market rely only on the adhesive system for both color and UV protection, both of which in time are very likely to dissipate. However, the full body dyed weatherable polyester and ultraviolet inhibitors in COOL N LiTE® professional quality films are an integral part of the film itself and guaranteed to screen out 99% of the UV rays for the life of the film.
(IR) INFRARED RADIATION REJECTION
In overly simplistic terms, the CNL series of metallised films reflect light, including in the infrared range, through hundreds of layers of nano particles that individually act like mirrors.
CNL high tech solar films utilise a clear multi-layer PET film (120 gauge) that is an interference based optical filter. An interference filter or dichroic filter is an optical filter that reflects one or more spectral bands or lines and transmits others, while maintaining a nearly zero coefficient of absorption for all wavelengths of interest, i.e. high Visible Light Transmission.
In addition, UV rays tan the skin but are also directly related to various types of skin disorders, cancers and eye problems such as cataracts. While it is virtually impossible to completely avoid all contact with ultraviolet radiation, there are preventative steps that can be taken to reduce or minimize the risks of overexposure, such as wearing long and closely woven clothing, proper sunglasses, wide brim hats and sun-screens with a sunprotection factor (SPF) of 15 or higher on all exposed skin. In most cases, standard plate glass or automotive glass is fairly efficient in preventing UVB radiation from passing through it, which is why it is difficult to get a sun tan behind glass. However, a very high percentage of the UVA radiation still penetrates standard glass and can significantly contribute to skin problems.
An interference filter may be high-pass, low-pass, band-pass, or band-rejection. The CNL material is a band-rejection filter. The multi-layer clear base film rejects the wavelengths from 900 – 1100 nm. In fact, in certain wavelengths, it could block out 100% of the IR energy transmitted from the sun!
Dichroic filters use the principle of interference, and produce colors in the same way as oil films on water. When light strikes an oil film at an angle, some of the light is reflected from the top surface of the oil, and some is reflected from the bottom surface where it is in contact with the water.
Because the light reflecting from the bottom travels a slightly longer path, some light wavelengths are reinforced by this delay, while others tend to be cancelled, producing the colors seen. This is why some of the CNL series changes colors when viewed at different angles.
In a dichroic mirror or filter, instead of an oil film, alternating layers of optical coatings with different refractive indexes are built up to make the filter. The interfaces between the layers of different refractive index produce phased reflections, selectively reinforcing certain wavelengths of light and interfering with other wavelengths.
By controlling the thickness and number of the layers, the frequency or wavelength of the pass-band of the filter can be tuned and made as wide or narrow as desired. Because unwanted wavelengths are reflected rather than absorbed, dichroic filters do not absorb this unwanted energy during operation and so do not become nearly as hot as the equivalent conventional filter (which attempts to absorb all energy except for that in the pass-band). In the CNL film, many alternating layers of PET with two different indexes of refraction are used to create the filter. The 120 gauge film is made up of several hundred layers of co-extruded PET.
METALLIC SPUTTER COATING TECHNOLOGY
Sputtering is done in a vacuum chamber where the metallisation process is achieved at the atomic level. In brief, electromagnetic fields direct streams of ions from a chemically inert gas (argon) toward the metal. This ion bombardment, which is often described as ‘atomic billiards’, causes groups of atoms to dislodge in small bursts and scatter uniformly across the film.
The practical benefits of sputtering are that 25 to 30 different metals can be used and the metallised coating is much lighter. It’s possible to sputter metal in a layered one hundredth the thickness of a human hair! Different metals are chosen to spectrally select specific wavelengths of radiation from the solar spectrum. The result is a highly reflective layer with very little mirror effect, heat absorption or colour shift.
Sputtering is a relatively more expensive process as compared to conventional processes like Vapour Depositing Process. However, the end result is a product that efficiently reflects heat, conserving energy and money spent towards cooling costs.
Cool N Lite® high tech film is probably one of the industry’s highest quality heat shielding film manufactured in this decade. The film is layered in fine polyester material with extreme optical clarity laminated together with PET coating, ultraviolet inhibitors, protective scratch coating, and then bonded using quality UV inhibitive adhesives that is developed to last through the lifetime of your application.
These range of solar films are manufactured with the industry’s latest technologies, using only the finest materials to guarantee a long lasting performance for your investment.
This differentiates from the conventional dyed coloured film or metallised film, as Cool N Lite® film maintains its heat shielding capacity nearly infinitely. The metallized color is stable, the heat rejection performance is unbeatable.
This film construction design makes it possible to achieve high levels of transparency and heat rejection levels close to theoretical limits.