Window Sun Shade

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Window Sun Shade

Simple Sun Shade Can Greatly Reduce Summer Sun Heat Gain

Background -

May 2006 - If you can tolerate having one, or several of your windows look like this from the outside, inorder to greatly reduce the heat gain of your south and west facing windows, then you should read on about this simple method to involve.

I originally came up with this idea when we first bought the house, to stop sunlight radiant heating of the house through the windows, which had aluminum triple-track storm windows in front of all the old double hung windows. And, like many home buyers, funds were tight and I needed a very inexpensive solution.

The space between the storm and prime windows easily allowed 1/2 to 1-inch thick foil faced foam panels to be installed between them. This created what my wife nick named our "cave mode" summer window treatment. In this example, a 1/2-inch foil faced foam panel is placed between the double glazed window and it exterior screen.

Here is the inside view of my south facing office window (outside shown above), on the second floor of my garage office. It's a 1984 Anderson Series 200 double glazed unit, one of the lowest cost models, which I installed in order to gain additional illumination in the room, which had no window on the south wall. Unfortunately, the summer sun and its radiant heat coming through this window, was greater then this 1984 window could handle, given its technology at the time. Pretty good in the winter, terrible in the summer.

I tried a number of ideas to stop the heat gain, but this was the best one I came up with. It is simply a 1/2-inch piece of foil faced foamboard (Rmax brand in my case) with its edges covered with aluminum tape to protect the exposed foam core from sun damage and consisting of three sections, held together on the backside with DUCT tape, as shown. I cut this panel 1/8-inch smaller then the window frame opening, where the foam panel would be placed, to allow for thermal expansion.

The DUCT tape serves to hinge the panels to fold together for storage, but more importantly it allows the panel the flexability to be placed between the the outside of the double hung window and the inside of the window's exterior screen. On windows with very little space between the window outside surface and the screen, you can use large silver mylar automobile windshield sun shades, cut in two pieces, with the upper piece taller then the lower piece, so that it will overlap the bottom piece to allow rain to run off. Two pieces also allows one to be removed for ventilation, such as at the top or bottom of the window.

This is the foil faced side, which has aluminum tape reinforcing the hinged areas as well as protecting the foam from the sun. You have to apply the aluminum tape with the panels folded together, so that their exposed foam core material will be properly covered, as shown below.

Here you can see what the panel looks like in its folded state, with the foil surface on the outside. I used pieces of cardboard as templates to first determine how big the sections should be, so that they could easily be maneuvered into place between the window and screen, or storm window, from the inside. A few were constructed to go in from the bottom sash, because the upper sash wouldn't open... later found to be screwed shut by overly long aluminum triple-track storm window frame screws!

With panels completed, lower the window top sash and place the first panel section in the window in front of the bottom sash as shown.

With two of the three sections now in front of the lowered sashes, you can use this configuration for ventilation, leaving the upper sash in the lowered position, reducing the amount of sunlight entering the window. This really works well in the late spring and early fall, when the air is cool, but the sunlight is very warm.

With the final section placed at the top, hold it in that position while you close the upper sash. The window is now totally shielded from the sun. The small bluegreen thing in the bottom sash between the window and the foam panel, is a piece of packing foam material, which holds the panel against the window screen and keeps it from moving back toward the lower sash window, allowing daylight in at the top of the window.

With my heavy drapes closed, there is no heat or light entering from this window. The heavy drapes are used for acoustical treatment because I do audio work in this room. And they provide additional protection against winter cold, too.

Questions or comments? Get back to me.

Rod Paine