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A good question on solar blinds

Here’s a question from reader Dan in Canada:

I am seeking information on solar blinds. I am up in Canada but have south facing windows in our home which cause tremendous heat in the summer, even with our Energy Star-rated windows.

I have seen manufacturers of so-called “solar blinds” talk to their value without disrupting the view from the inside and wanted to know do they actually work, if it is better to have the kind on the inside or outside the window and who produced the best solar blind?

I have seen a few manufacturer websites and think that the ones from EZ Snap seem to have the best possibility costwise (under $3 per square foot), but I just don’t know.

Thanks in advance,
Dan

Any advice for him? Please comment below.

5 Comments on A good question on solar blinds

  1. Dan,
    The EZ Snap solar “blinds” likely have some effect (the company claims they block 90% of the sun’s heat). Actually shading the window with an awning, pergola or extending your eave will be more effective. Here is a link with the equations of how to size them for your latitude.
    http://www.yourhome.gov.au/technical/fs19.htm
    Ted S

  2. Oh, and it’s always better to block the radiated energy outside. If you use something inside be sure it has reflective properties (shiny and white). You will not be able to see through an effective radiant barrier.

  3. One more thought. I am in the same situation at a lower latitude.
    If your windows are getting that much solar radiation, so are your south facing walls. The heat gain from the radiated walls is likely as much as the heat gain from your windows.
    Proper shading will have your south walls completely shaded on June 21st (?), the date of the north limit of the sun’s travel over the face of the earth. If your latitude is 50 degrees N, the sun will be overhead at [90 - (50-23.5)] = 63.5 degrees. Your shading will need to stick out enough from the vertical wall to shade a 63.5 degree angle at the bottom of the wall.
    If you have a single story with a 9′ eave height, the length of the shade (hypotenuse) is [sin 63.5 = 9'/h] [h = 9' / sin 63.5 or h = 10.06']. That allows you to calculate the distance from the wall for your shading [cos 63.5 = x / 10.6 ] [x = 10.06 * cos 63.5 or x = 4.49'].
    Obviously a 54″ overhang/eave is not practical so some alternate form of shade is needed on your home to take advantage of the passive heat gain in the winter and avoid it in the summer. I have reached the conclusion that the pergola option is best for my south wall.
    Good luck!
    Ted S

  4. I have two issues with my south facing windows. The heat from the sun and there is one more issue that needs some explaining. We have a water processing plant about 30 feet away from our house on the South side. There is a street and a golf course between our house and the processing plant. I’m concerned about radiation from that plant. I wonder if the solar blinds block electro magnatic waves as well.
    If someone knows about electromagnetic waves, how much of a health hazard this plant may be and if there any measures I can take to minimize the harm–I’ll truly appreciate sharing the information with me.
    Shaila

  5. Hi,
    I’m back :-) Well, we did end up purchasing the EZ Snap exterior solar blinds and are very pleased. They were very easy to install over our newly installed replacement windows. We opted for the 3M adhesive hardware so not to make any holes in the new metal window frames.
    We can see outside more than what we thought, so that is good news from an astectics perspective. But the best news is that we ran a test using a portable temperature guage and the installed product reduced the reading by 15 degrees F. That was very impressive. If you are interested here is the link to the article on our blog with the before and after: http://dailyhomerenotips.com/2008/05/04/exterior-solar-blinds-part-7-installation-results-from-the-inside/
    This weekend we are going to install them on the outside of the outswing French Doors in the kitchen eating area (also south facing) and get rid of the blinds that are on the inside of those French Doors to make more room in the kitchen eating area.
    Dan

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