Cool it down: specialized window film allows glass-enclosed facilities to bask in the sun, without overheating.(BOTTOM LINE)

It's hard to beat the beauty and aesthetics of a glass-enclosed pool or waterpark. Natural light and the ability to see the outdoors makes for a more enjoyable aquatic experience for everyone.

But that experience comes at a price. According to the California Energy Commission, 30 percent of the cooling requirements of a glass-enclosed pool is caused by heat entering through the glass.

Stopping heat at the glass with solar-control glass or applied window film is the best solution. However, solar-control glass often exceeds the cost of standard glass to which a solar control film is later applied.

That's why for new construction and all existing glass-enclosed facilities, applied window film typically is the least expensive and preferred option.

But not all window films are created equal. Conventional window films successfully block a significant amount of solar heat. What's more, most of these films have a mirrorlike appearance from the outside. In artificial light and at night, they also can appear mirrored inside.

The result is darkened pool interiors and a reduced ability to see into and out of the water. This can lead to higher utility costs, which defeats the major benefit of the film cost savings. That's where clear, spectrally selective window film comes in.

"Spectrally selective" refers to the ability of the film to select, or let in, desirable day-light while blocking out undesirable heat. It offers the best ratio of visible light transmission to heat rejection.