Many homes and office buildings are built to take advantage of a view. Naturally these structures offer multiple windows to enjoy it. These windows permit brilliant natural light to shine in which adds life to the space. The real issue arises from the low insulation value of windows and is multiplied by the solar heat gain. Therefore many of the new windows have incorporated Low-E coatings to help deal with the heat gained through them.
The multitude of film options that exist today generally fall into two categories: Low-E coatings and reflective window films. These coatings offer an immediate cost effective solution. Existing buildings can achieve major benefits without replacing all the windows by simply applying the proper window film.
Utilizing the proper window coating can dramatically reduce the solar gain, thereby decreasing the cooling load on the HVAC unit. In fact, the DOE states, “Computer simulations have shown that advanced window glazing with spectrally selective coatings can reduce the electric space cooling requirements of new homes in hot climates by more than 40%.”
Low-Emissivity Coatings
A Low-Emissivity coating, otherwise known as Low-E, is a thin film that is virtually invisible. Most of these coatings are applied in the factory for new windows, but some are available for the do it yourselfers. Aftermarket options are generally inexpensive, especially when compared to the cost of total replacement. Many of these products come with a ten to fifteen year warranty against fading, peeling and other signs of aging.
These coatings are designed to be spectrally selective and can allow for different levels of solar gain depending on your climate zone and design specifications. They are optically designed to reflect infrared light while allowing visible light to pass through virtually unobstructed. This allows the benefit of naturally lighting a space without the extra heat collected by the windows.
Reflective Window Films
Reflective window films have a metallic finish and many appear silver in color. They help with glare reduction and can cut solar gain by as much as 79%. 3M claims that their film can block out 99% of UV light protecting your furniture from the sun’s harmful rays. The effectiveness of the film depends on many factors such as the size of the window and the climate zone. The major disadvantage of this type of film is that it is not spectrally selective and therefore reduces the amount of sunlight into the interior. Other concerns include extra care while cleaning reflections and impairing your ability to see the outdoors.
