How do sun screens block solar heat gain?

If you grew up in a climate with four seasons, then you probably remember having to take off the winter storm windows in the spring and replace them with the wood-framed aluminum screens for summer-time ventilation. Well, here in the desert we are faced with the task of repairing the screens that have rotted away from the intense Arizona sun or from pets or people walking through the arcadia screen doors.

The function of a sun screen is to prevent UV rays from ever reaching your windows. With today’s products and technology in screens you can greatly reduce the heat gain through windows which are the highest contributors to heat gain in most homes. Sun screens work in three ways:

1. Shading efficiency, the amount of shade created between the screen and exterior pane of glass.
2. Reflectivity, the ability of the screen to reflect the sun’s rays away from the window, which keeps heat from touching the glass.
3. Absorption, the heat that is absorbed into and held in by the screen material and then dispersed back into the air and away from the glass.

For maximum efficiency, two elements are particularly important. First, sun screens must be built to fit the exterior of your window with the spine facing out; this creates an insulating air space between the window and sun screen. Second, and just as important, is the screening material. As you may already know, we are not big fans of vinyl products in the desert climate. However, we have found that vinyl coated sun screens are very effective since the material can be produced cost effectively. The average lifespan of screen material is seven to ten years for fiberglass and over ten years for vinyl coated screens, in which time the screen has already paid for itself several times over.

Sun screens are only as strong as their frames. Quality frames will last as long as you own your home so consider strong metal frames when shopping for sun screens. Make sure the frame is constructed of aluminum measuring 1" inch wide, 7/16 deep, and .025 thick. Make sure the corners are made of aluminum also, not plastic which has a tendency to dry out and break over time.

Regardless of what you may read, sun screen material will not block the view from inside during the day, in fact, it prevents anyone from looking inside. At nighttime this effect is reversed if there is a light on inside the home. In other words, if two people are looking at each other through a sun screen, the person on the darker side will be able to view the lighter side.

Sun screens also work to prevent insects from entering your home if you keep the windows open during the Valley’s beautiful spring and fall months.

When cleaning sun screens, use soapy water, a garden hose, and a soft bristle brush to scrub off the dirt and grime. I would recommend taking the sun screen off the window and cleaning both sides. Vinyl coated sun screens can be wiped down with a non-petroleum based vinyl protecting product to make them look new after they have been cleaned.