Are We Clear

Summer sunlight streaming in through your windows can be a beautiful thing – until it heats up the inside of your house like an Easy-Bake Oven. Depending on when your home was built, protection against “Solar Heat Gain” varies widely. In the 1990’s the residential window industry began addressing the issue of solar heat gain by producing windows with low-e coatings. Older (pre-1990’s) windows without coatings are called “clear” – even double-paned, insulated assemblies may have “clear” glass depending on when they were made. Newer windows come standard with low-e coating – in fact, our local building code requires windows with a Solar Heat Gain Coefficient (SHGC) of 0.4 or less in new construction. So what’s an older window to do? One option for retrofitting “clear” glass is installing window film.

Window films form a semi-permanent bond using adhesive that is activated by spraying on a diluted compound of water and pure soap (such as baby shampoo) Once the adhesive has cured (2 days to 1 month depending on product), it forms a fairly tough seal that can only be removed with a great deal of effort.

If you’re considering installing window film yourself, a number of brands are readily available through home improvement stores. High quality films can also be ordered over internet. Before tackling this job, be well prepared and have your method thought out beforehand. Patience, preparation and a bit of practice can take you a long way. These websites have some great instructions and tips for the do-it-yourself crowd. (Window Film Installation Site 1, Site 2)

If you’re not feeling up to a Do-It-Yourself job, a number of companies can help with both film selection and installation. LaGrange Consulting recommends GT Tint Solutions (Greg Taylor – 985-966-4953) or Solar Solutions (Peter Caughman – 504-525-5880) to get the work done.

There is a limit to how much radiation can be blocked with coatings and films. If your existing windows have a fairly low SHGC, adding window film won’t be much help. The only way to reduce solar heat gain in those cases is to physically shade the window on the exterior (planting trees, installing shutters) or interior (using blinds and drapes).

There are a few places that residential window film should not be applied, such as: Plexiglas panes, motor vehicle windows, frosted, etched, leaded, cracked, holed, deeply scratched or older glass (40+ years).

This blog was written for Paul LaGrange’s BuildWrite website and was originally posted on August 7, 2009.


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