Need help in choosing windows

I have double pane clear windows now and the heat in Texas is brutal. I hate the looks of the solar screens so have checked into the low-e glass. I found a local company who can replace some of my windows and they gave me a choice of cardinal low e squared, or guardian PP2 I think they call it. While investigating windows, I found so much as far as seals and gas, and did ready up on guardian and cardinal. Cardinal seems slightly better for our climate but I could be wrong. I have aluminum windows already so am getting the inserts replaced which is quick and easy. They told me they use spacers and the frame and seal the 2 glasses but don't use any argon or any type of gas inbetween, just air. Is this important or does it matter? I want to do a section at a time and since the one area already needs windows, that is easy. However I want to get the best efficiency possible. Thanks for any info.

Guest User
Tue, 08/08/2006 - 17:25


Well it sort of depends on where you live in Texas to determine what is the most energy efficient window. If your most concerned about just the summer then the Cardinal product will work well. Certainly much better than double pane clear glass. I'm not as familar with the Guardian product, but there is an easy way to figure it out.

Go to the following website

Download the software called RESFEN 5.0 (its free). This is an energy calculation tool, and will tell you for your area what is the most efficient window you can buy.

You will need the following information on the products you want to compare.

U value
SHGC (Solar Heat Gain Coefficent)
The window should have a sticker on it with these values or the installer should give you this information if you ask. If he won't give it to you then walk away.

It would also be nice to have the square footage of your window area North, South, East and West, but not critical.

Once you have it installed and running set the information on the left to your type of house and city location.

Set the window type to "User Defined" and enter the Uvalue and SHGC information then click the double lightning bolt at the top of the screen. You should get values for total heating and cooling for this window. Write down the numbers and compare to the Guardian values.

PPG also sells a similar product called Solarban 60.

If you buy the windows don't forget to save your receipt for taxes you can write off a modest amount ($200) for this year.

In your climate air vs. argon will not make a big difference. Argon is used in Northern and North Central climates for lowering the Uvalue (reflects more heat back into the home).

Biggest thing is make sure they know what they're doing. Improperly installed energy efficient windows are completely useless to you.

Good Luck!

Guest User
Tue, 10/07/2007 - 04:40

Also check out this website, to learn about getting a tax credit for installing energy efficient glass in your windows and much more.

Guest User
Tue, 10/07/2007 - 03:32

For regions such as yours, you need a spectrally selective glass in your window. This type of glass limits the amount of solar energy radiantion into your room, as well as the transfer of radiant heat. It means that you should get a double glazed unit in your window which offers the lowest Solar Heat Gain Coefficient and minimum U-value. Spectrally selective glass is a coated glass with tint, to absorb and reflect solar energy. To be effective, make sure the coating is facing on number 2 surface of the glass, counting the surface from outside. For more details visit the website, to find out about energy star rated windows.

Guest User
Thu, 30/08/2007 - 08:21

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