You are right.

The only truly effective heat preventive is a sunscreen OUTSIDE the glass, so the heat never enters the house. Everything else just traps the heat between window andshade, slowing the entry, but it's still inside.

Faithab: I went through a bit of testing with the same questions in mind. The big question is if you have low e glass in the windows. If not, you can reflect or reradiate the heat back out. If you have low e, the only option is to reflect it. Mylar (aluminum) coated shades will reflect direct or reflected sunlight back out through the low e glass without trapping much at all. It is best to use a pull down shade rather than put it on the glass itself however, as some heat is stopped. Almost any fabric you would use for a blind would absorb and reradiate the heat, and if you have low e, the radiated heat will not go back out and be trapped in the room.

To check if you windows are low e or not
a little trick I used in the field
before I got a light meter...

Flick a bic lighter and hold close to window.
If all 3 flames (flame on lighter and both glass
reflections) are the same color the glass is clear.
If two are orange and one yellow you have low e
coating.

I would think given the heat gain you are experiencing
that you have clear glass.

Tinting your windows may be an option.

You may want to check out Exterior Solar Screens

Those sheerweave solar shades look nice. I had a 5th floor apartment with double pane windows facing dead south that really heated up. I got shades that sound like those mylar shades They were a plastic that looked like a metal foil from the outside. You couldn't see into the house during the day. From the inside they were see through and looked like tinted windows. They were really really good . As soon as I pulled down the shade you could feel the roasting heat disappear. Kind of Jetson's looking from the outside. They gave no privacy at night

I am looking for a way to keep the heat in my home, especially near my patio door. The exterior screens look interesting, but I let my neighbor's cat in and out at least twice a day and he is the most destructive shredder of screens I've ever met! Is there some type of film I can put on the exterior of the door to help with heat loss in the winter and to prevent heat gain in the summer? The door (and all but one window in my townhouse) faces due west, so I'd like to reduce the sun fading I experience also.

Thanks!

Hi Guys,

Please check here, you'll find what you're looking for.
http://energysavingblinds.actieforum.com/portal.htm

Cheers,

Here is a link that might be useful: http://energysavingblinds.actieforum.com/portal.htm

Do you have an awning?

Charles King

Here is a link that might be useful: Energy Saving Education at 8th Sister LLC