Window film technology has been helping to cool, beautify and protect buildings for generations, it is popular for protecting interior furnishings and floor and wall coverings from fading as well as reduce heat load in the summer. Now revolutionary advancements in window film technologies will not only prevent heat gain and sun damage, it contains properties that serve as an effective thermal insulator.
Commercial building operators have been using various varieties of window tinting to prevent suns damage and heat but are largely unaware of these additional benefits.This process is also not as dark and reflective of previous generations, and is capable of transforming the appearance of a building with a more uniform appearance.
There are many brands and varieties of window solar barriers on the marketplace today. Each boast of their ability to block or render harmless various solar wavelengths that have proven harmful and increase internal temperatures. The most common solar band that window manufacturers seek to shade or disrupt is infra-red. This harmful band-with is most effectively reduced with a coating called Low-E. The low –e treatment or window glazing has been a staple of the industry for over a decade. Low-e coatings have improved in effectiveness over the years and the problem of visible iridescence from first generation applications has been eliminated. A quality low-E treatment will effectively slow the fading and sun bleaching of interior assets. Buildings without infra-red protection can be as much as 20 to 25 degrees warmer that one protected with traditional treatments.
Low-E coatings however are unable to reduce thermal conductivity or an observers ability to view interior conditions. Highly visible landmark buildings are discovering the elegant beauty of a building with a consistent look about the windows. Designers and architects agree that the view of a buildings exterior is more desirable when it is difficult to notice the interior lighting and the variety of positions of the window blinds.
The remarkable difference of this product is its unique ability to reduce the thermal conductivity associated with window glass. Since windows represent the largest energy loss of the building envelope this process has important implications. This advanced window tinting comes in many different color and shade variations and may be eligible for incentive programs in your area. With or without incentives this technology should pay for itself well within three years and forever improve the value and appearance of facility.
Window films have been used for decades for many reasons, but one primary benefit of architectural films are their ability to reduce energy in commercial buildings and homes. Advances in the manufacturing of architectural window films, using all-metal films with no dyes to change color and innovative adhesive systems that securely adhere films to glass for many years, have enabled film manufacturers to typically offer 10-15 year warranties on many products used in non-residential settings, and often lifetime warranties in residential applications. Window films of today are durable products, protected by UV-absorbing layers that usually block 99% or more of the UV rays and a resilient scratch-resistant coating for easy cleaning and no maintenance. Many applications around the globe have been in service for more than 20 years providing long-term energy savings while maintaining a nearly-new appearance.
Most window films typically consist of a thin (0.025mm, 0.001 inch) polyester film substrate that has a micro-thin, transparent metal coating applied to one side that reflects and absorbs the sun’s energy before it can be transmitted into a building space. By reducing the solar heat gain through windows and reducing the building cooling load, window films reduce the amount of time that a building’s cooling equipment must run to maintain comfortable conditions, most often resulting in electricity savings. Savings of 5-15% in total building electricity costs, kilowatt-hour consumption, and kilowatt peak demand can often be achieved, with the savings amount dependent upon several factors, such as: glass type, window to wall ratio, presence of overhangs, climate, performance level of film used, and the efficiency of the building’s cooling equipment.
While providing excellent cooling season savings, these “solar-control” window films often suffer from one drawback, in that they reduce solar gain through windows all year long, even when such heat gain may be desired (as during the heating season). So, in climates with prolonged heating seasons, on some buildings solar-control films may actually increase the amount of heat that must be supplied by the building’s heating system. The gain of free solar heat during winter typically is not a large amount, as during winter there are considerably more days with cloudy weather and the hours of daylight during winter are less than during summer. Even when heating needs are slightly increased the overall net effect is still positive with cooling savings more than offsetting the loss of free solar heat in the winter and “solar-control” window films providing attractive returns on investment.
When desirable to produce improved annual savings and to overcome this minor drawback, low-e window films are available. Low-e films improve window insulating properties sufficiently to offset the loss of free solar heat during the heating season and typically provide both cooling and heating savings.
The low-e coating of these films (and for low-e windows) helps reduce the loss of room heat during the heating season. One way that heat is lost through windows during the heating season, is that objects within a room are warmer than the surrounding outdoors and the objects in the room will then radiate heat towards the cooler outdoors. For windows that are non low-e, much of this radiant heat is absorbed by the window glass as it attempts to escape to the outdoors causing the glass temperature to increase slightly. As the glass is warmer than the outdoors, this absorbed heat is still radiated to the outdoors. With a low-e film applied to the room side of a window, the room’s heat attempts to radiate to the outdoors, but the low-e coating of the film does not absorb a significant portion of this radiant heat and reflects much of this heat back into the room. The degree to which percentage of heat is reflected back into the room in this manner (and how much of this radiant heat is absorbed and lost to the outdoors) is associated with the film’s emissivity.
Most films have an emissivity equal to that of glass of 0.84. So, when objects in the room try to radiate heat to the outdoors during the heating season, the film (or plain glass) absorbs 84% of this heat, most of which as described above is subsequently lost to the outdoors. Likewise, only 16% of the room heat is reflected back into the room. When a low-e film is applied to the glass on the room side of the window, with an emissivity of say 0.35, then only 35% of the room’s radiant heat is absorbed by the glass and lost outdoors, and 65% is reflected back into the room, resulting in heating energy savings. Windows with low-e coated glass work in a similar manner to reduce heat loss during the winter.
One key point is that low-e coatings help to reduce the flow of radiant heat from the warmer side of a window to the cooler side. In winter low-e films (and windows) reduce heat loss, but in summer they help to reduce heat gain, so low-e coatings help to provide year-round savings.
A second key point is that the lower the emissivity of the film (or window glass), the more improvement in reducing the flow of heat through a window (during winter and summer). As you can see from the example above, our film with an emissivity of 0.07 is reflecting 93% of the room’s heat back into the room during winter, which is significantly better than the level of room heat reflected back into the room by most low-e films (65%) with emissivities of about 0.35, and far greater than most standard window films with emissivities of 0.84 (only 16% of room heat reflected back into the room).
A final point concerns low-e window film appearance. While conventional low-e films help reduce energy costs in all seasons, they can display an unpleasant iridescence or “oil slick” appearance when installed near certain types of energy-efficient lighting, such as compact fluorescents. Our advanced window film’s low-e coating was developed in such a way to minimize this iridescence, providing for a more aesthetically-pleasing film.