Window films have often been associated with dark, tinted, mirrored or frosted surfaces, but modern spectrally selective films can achieve high levels of heat rejection and be almost completely clear. These types of films, known as "clear" films, are designed to provide many of the same benefits as traditional window films while remaining virtually invisible.

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Window films work by reducing the solar radiation rays that transmit heat and UV rays into a space. Years ago, the higher heat rejection rates were traditionally associated with darker films because the film technology was not as advanced as it is nowadays. This means that the only way to disrupt UV and Infrared rays was to also disrupt some of the visible light rays as well. Modern day films are different. Spectrally selective films, like 3M Prestige 70, can reject 99% of UV rays and 97% of infrared rays while remaining virtually clear. They avoid rejecting visible light to maximize the view-through factor of the film. 

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The advantages of these clear films are that you don't compromise on visibility to achieve high levels of heat rejection. Typically high performing films like 3M Prestige 70 will achieve a similar heat rejection to much darker films. In this way, you can increase the energy efficiency of the building without changing the look from the inside or the outside. It's an excellent option for those looking to decrease the carbon footprint of their building. Once installed, Prestige 70 can become carbon negative in as little as 6 months.*

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When it comes to these clear spectrally selective films, we have seen that 3M Prestige 70 is usually the leader of the pack in performance. Even though the difference is usually only a few percentage points, 3M Prestige series window film is able to achieve this superior performance with no metals, where as most competitors are using metalized window films. This is very important because metalized films come with their own disadvantages, like signal interference and occurrences of corrosion in coastal environments. 

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It is important to note however that there is no such thing as a film that is 100% completely clear. Even clear glass is not 100% completely clear. In the glass & glass solutions industry the most commonly used metric is VLT (Visible Light Transmission), and anything over 50% is usually considered very clear. Most roller shades are between 1%-5% VLT, most sunglasses are 15-20% vlt, the majority of window films are between 15%-50% and a standard quarter-inch "clear" glass is about 83% VLT. 3M Prestige 70 has a very high VLT of 70% and it has lower interior reflectivity than glass, making it one of the clearest films you can install. 
 

Overall, spectrally selective films like 3M Prestige 70 are a versatile and effective solution for those looking to improve energy efficiency, comfort, and fade protection without changing the appearance of their home or office windows. They can provide almost the same benefits as traditional window films while remaining almost invisible. It is important to note that these films are best installed by professional installers, and it is recommended to always use the manufacturer's recommended professional installers to ensure proper installation and warranty.

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*See environmental product declaration at environdec.com/library/epd994