[Greenbuilding] Solar shades

[George J. Nesbitt]

Did you forget rule #4?

#4 "omitting properly scaled overhangs or other permanent shading devices to  
prevent unwanted gains during the summer months." Rob Tom (South windows need to be shaded in the summer, or you get overheating. East and west windows are harder to shade with overhangs, they have to be very wide and deep. East and west glazing should be minimized).

So, you could add a deep and wide trellis or porch to shade the windows. 

You are right in letting the heat in the windows and then trying to stop it with a shade is not the best way to go. And if you have Low E it won't let it reflect back out.

You are also right that west windows don't help much in winter when you need the heat gain the most. 

You could add window film on the inside, there are now Low-E film products that are almost clear (V-Cool, 3M). 

An exterior window screen/shade is a good way to go. You can use it in the summer when you need it, and remove it in winter when you don't. Something that rolls up would be most practical, so you don't have to remove, install, store and damage it. (I plan on doing this some day).

The more heat you reject, the more light you cut out. I can tell the difference when I put my window screens up for the summer.




Lawrence Lile wrote:
> I've got a couple of West windows, and I had planned to put some external solar shades on them about the time simmer comes along.  Well, Summer is here!  The computer model says that the three windows on the West are like 25% of my air conditioning load.  Sheesh.  West windows are terrible energy hogs, they contribute little solar gain in the winter when you need it, and plenty of solar gain in the summer when you don't.  Ah, but sometimes, you just need to see out to the West.  
>  
> A perusal of Home Depot's offerings revealed three kinds of rollup external shades.  "Natural oak" which is made of real, actual basswood; bamboo; and PVC.   ("Oak" now refers to a color, not to a species of tree. Next they'll have "Real Wood" made of polyethylene.)  
>  
> The helpful shade lady who seemed to have been selling shades for quite a while claimed that the bamboo rollup shades, which were my preference, would fall apart in a year if used outdoors.  They were definitely labeled for indoor use.  She recommended the PVC shades, which I could not really stomach.  Basswood shades weren't labeled for outdoor use, and I didn't think they'd hold up either.  
>  
> The reason you want external sun shades is, of course, to keep out sun and heat.  If you put them on the interior, in a window with direct sunlight, you risk cooking the window seals and components.  Also, you've already let the heat into the house, you'll absorb more of it than you realise if the shade is on the inside.  
>  
> Another idea I considered is a heat reflecting solar film.  This is also readily available at Hoem Depot, and I can report that it looks like it is 100% easier to use than the films I tried years ago.  Those old films, once you stuck them on there was no fixing them, so if you made a bubble or a wrinkle then you had ti live with it.  Now there is some kind of liquid stuff you spray on the window, and when you are satisfied with adjusting the position of the film, you squeegee it out from under the film.  
>  
> I figured a film that rejects 70% of the suns heat would get me pretty far toward the goal.  However, the wife nixed the idea, for asthetic reasons.  There is no arguing with someone's opinion of art.  
>  
> So I'm kind of stuck on trying to shade this West window.  Any ideas?  Do  the bamboo shades really fall apart after one season?  
>  
> --Lawrence 
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