Showing posts with label SHGC. Show all posts
Showing posts with label SHGC. Show all posts

Sunday, May 16, 2010

Buying New and Retrofit Windows in Denver

You really only need to know two words on this topic: Window World

Call and ask any company how much they charge for installed windows, they'll say, "let us send out someone to measure, and we'll give you a quote". Fair enough, but you've just committed to one hour with some likeable guy who doesn't value your time that much.

With Window World, just count your windows, then multiply by $250. That's awesome. Of course, they have some options, some of which you need in order to receive the 30% federal rebate. Note that they don't even care about the size. Some windows are bigger, and some smaller, they figure.

As good as they are, you may find confusion when it comes to that all important SHGC number I keep harping on. (Some other guys have started major harping as well )

It just doesn't matter that much. You need some affordable windows NOW that actually go up and down and close tightly. Your south windows are shaded by your neighbor's trees anyway.

So I say go with whatever you can afford.


Friday, December 4, 2009

Solar Cats and Passive Solar Energy Collection


Did you ever wonder what the surface temperature is of your solar kitty?

As you can see, Natasha runs about 112F on a clear, cold winter day in Denver. Note: she is laying in front of a window with an SHGC (solar heat gain coefficient)of 0.56. That's far higher than the average low E window which has an SHGC of about .32. What's that mean to a cat? About 15F. A black surface in front of a conventional low E window under the same conditions is around 97F. Still warm, but that's a significant penalty for not specifying the right windows.

Hurd "hard coat low E" windows from Rocky Mountain Solar Glass has been the only local solution I have found for passive solar. Serious Windows (formerly Alpen) should also be able to supply a high SHGC low E window. Most other window suppliers and manufacturers have no clue about this issue.

Increased solar gain in the summer isn't a concern, because these are south facing windows. In the summer, the sun is high in the sky, and the window is completely shaded by the properly designed overhangs. Even the Energy Star program is silent on this, although their energy modeling computer programs do give credit for high SHGC windows on the south side.