Generally, window film provides specific personal and property protection from the effects of the sun as well as added safety and security in the events that result in broken glass.The concept of window film for use in solar control flat glass application dates back to the early 1960s. The original film design objective was to control the heating and cooling imbalances that result from solar loading. Such early films were found to reflect solar radiation back from a window, preventing the warming of inside surfaces normally hit by direct sunlight while still allowing vision through the glass.
As the window film concept was developed and improved upon, a demand developed for colored sun control films that would complement architectural design. Coloration of film was achieved through various means to produce colors such as bronze, gray, gold, amber, etc.
The energy crisis of the early 1970s prompted an interest in another aspect of window film use: the reduction of heat loss to the outside. It was discovered that polyester film tended to absorb and reradiate long wave infrared heat rather than act as a transparent medium. Through experimentation, new film materials and constructions were developed that enhanced this characteristic. These films greatly improved heat retention within a room’s interior.
The efficiencies of solar control window films are closely related to local weather conditions, building orientation, window size, and other factors such as exterior shading conditions. However, with escalating energy costs, products such as window film are increasingly valuable as an investment for commercial and residential owners and commercial facility managers.
There are many types and constructions of solar control and safety window films. These films are considered in the building industry to be “retrofit” products; that is, products to be applied to existing buildings as opposed to use in new construction. In their simplest forms, window films are composed of a polyester substrate to which a scratch resistant coating is applied on one side; a mounting adhesive layer and a protective release liner is applied to the other side. When the release liner is removed, that side of the film with the adhesive is applied to the interior surface of the glass.
Benefits of dealer installed window film products for residential and commercial buildings:
In response to the many requests for a statement on the benefits of installed window film products the International Window Film Association has compiled the following information. This list may not include all potential applications and depending on the product recommendations, many products will not provide all of the benefits listed. It is the responsibility of the installing dealer, as well as the informed consumer, to determine which window film product will best suit their need. Working with an International Window Film Association (IWFA) accredited “Solar Control Specialist” assures the consumer that the dealer they are working with has successfully completed testing on important areas of technical and installation expertise.
All window films typically offer:
Increased shatter resistance resulting in:
Scratch resistant hard coating protects against:
With “Accredited Solar Control Specialist” installations you can expect:
There are six factors affecting fabric fading:
Clear single pane glass (1/8″ to 1/4″) will reject 23-28% of the ultraviolet light from the sun. Insulated glass is slightly better, rejecting 36-41%. Window films installed on glass reject 95-99% of solar ultraviolet light.
Different types of clear glass and window systems will reject 13-29% of the solar heat. With window films, 80% solar heat rejection can be obtained.
No window film can eliminate fading. It can, however, offer maximum protection from fading due to solar ultraviolet light and solar heat.
The effective life of window film will vary by the type of film, type of glass, window construction, compass orientation of glass, and in which part of the world the building is located. There are documented cases of film lasting 12 to 22 years or more in some instances. This should not, however, be assumed to be the normal expected life.
All quality window films for residential and commercial use are warranted by the film manufacturers for a minimum of five years (certain products may have extended coverage). The warranty includes an address to contact the manufacturer directly should any questions arise either before or after the installation of the window film.
Windows with film applied are easily cleaned without damage to their appearance as long as a few common-sense guidelines are followed:
The availability of scratch resistant coatings as a standard feature of quality films has virtually eliminated the need for extra special precautions in cleaning.
In most cases if a house plant is already receiving adequate light the use of window film will not harm it. New growth or flowering may be retarded, and, for a few days, a plant may go into a state of shock while it adjusts to the light change. If a particular plant normally wilts by the end of a sunny day, it will actually thrive better with film installed. Although there are some obvious guidelines in determining what, if any, effect window film will have on a plant (for instance, dark green plants need less light than lighter colored ones), there is one sample test which can be done prior to film installation: merely move the plant to an area with less sunlight for a few days. In addition, most nurseries or local agriculture agencies can advise you whether a particular plant needs closer to maximal or minimal light.
Whether window film should be used on low E windows and how much you will benefit depends on three factors:
There are two basic types of low E surfaces on glass. One of these is a conductive coating put on glass as it is being made. It gives some heat loss reduction, but does little to reduce heat gain into a building. The second type is a more complex system of multiple layers of metals and conductive coatings deposited on glass after it has been made. This type of low E glass gives heat reductions of 30% to 50% in addition to reducing heat loss. Obviously there will be more heat gain reduction using film on the first type. If there is any question about the type you may have, ask your glass company or the window manufacturer to send you the specific information about your glass.
The location of the low E surface in your window system is also very important in deciding whether film should be used. If the low E coating is on the room-side surface of the innermost pane of glass, the use of window film may reduce or eliminate the heat loss reduction of the glass itself. This may be more than offset by the heat gain reduction/heat loss reduction properties of the films to be used. Most low E window systems, however, consist of double pane windows where the low E surface faces the air space between the panes. In this case, film can be installed without eliminating the heat loss reduction benefit of the low E glass. The type of window film you choose for low E glass depends entirely on your desired benefit -whether you want to reduce heat gain, control glare, prevent heat loss, reduce fading or enhance the safety of your windows and glass doors. Carefully consider all these benefits before making a final decision.
Glass breaks when stressed. There are five types of stress which may cause glass breakage:
The first type, thermal stress, is the only one which film may affect. The use of window films will increase the thermal stress on sunlit glass. However, there are also other factors which will increase thermal stress such as: partial shading of windows from overhangs, tightly fitting drapes or blinds, signs or decals on windows, heating and cooling vents directed at glass. In addition, different types of glass (annealed versus tempered, clear versus tinted) have different solar absorption rates and will withstand different degrees of thermal stress.
The window film manufacturers have recommended film-to-glass tables for use by factory-trained dealer installers. If a consumer is ever in doubt, he/she should request a copy of such guidelines. Listed are some glass types or conditions where the use of a solar control (not clear safety) type of window film is not recommended without extreme caution.
SINGLE PANE GLASS LARGER THAN 100 SQUARE FEET.