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Window Film Repels Solar Heat

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Occupants of Inlow Hall at Eastern Oregon Univ., an historical building, used a spectrally selective window film to reduce the effects of solar heat while not compromising the building’s appearance

 

According to the California Energy Commission, 30% of a building’s cooling requirement is a function of heat entering through existing glass. Carol Kroll, director of human resources at Eastern Oregon Univ., La Grande, OR, certainly is a believer in that statistic. Her office in Inlow Hall, the university administration building, faces a wall of glass through which the sun often raised temperatures to more than 90 F.

Thanks to V-Kool’s clear, spectrally selective window film, Inlow Hall occupants are able to work in a cooler environment.

“It was impossible to work in the afternoons,” Kroll declared, explaining that an air-conditioning unit in an outer office did little to cool things down. In an effort to block incoming solar energy, Kroll applied gold- and silver-colored heat reflective film to the interior of her office windows. The result was not much of a drop in temperature but a definite raising of administrative eyebrows.

“Inlow Hall is an historic structure whose appearance can’t be altered,” Kroll explained. The use of colored film on her office windows was very visible and substantially changed the external appearance of the two-story building, which was built in 1929 and is listed in the National Register of Historic Places.

Rather than jeopardize the revered building’s enlistment in the National Register, Kroll removed the colored film from her office windows and tried less-obvious heat blocking options, including traditional window blinds and shower curtain rods from which was hung a room-darkening fabric. Nothing seemed to bring the temperature to acceptable levels.

Fortunately, Kroll learned about V-Kool clear window film, manufactured by V-Kool Inc., Houston. The product was originally developed for the United State’s space and defense programs and with a process known as sputtering in which tiny particles of exotic metals are embedded in optically clear, durable polyester film. A durable, pressure-sensitive adhesive is adhered on one side of the film. On the other side is a durable scratch-resistant coating to ensure a long life. V-Kool is spectrally selective and allows in 73% of visible light, while blocking more than 90% of the infrared spectrum. This means windows remain visibly clear but cut out 55% of the solar heat.

“We were particularly interested in V-Kool because it is a clear film that blocks heat, reduces the temperature, and does not change the appearance of a building,” Kroll explained.