How can someone test thermal and solar heat transfer on installed windows. I have relatively new double hung windows and in direct sunlight they seem to be very hot and I can feel heat radiating off the window in to the room.
Thanks
How to test thermal and solar heat transfer
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Re: How to test thermal and solar heat transfer
Solar heat gain and Ufactor are two different things. If you are in the northeast, you will likely feel some heat from the sun in the summer months, of course not nearly as much as your older windows. Why? You need some passive solar heat gain in the winter months which means some/ slight solar heat gain in the summer.
In the northeast, a solar heat gain of .25 - .30 is optimal.
Ufactor- .28 or lower.
Ufactor just measures how much heat escapes through the window in the winter months: the lower the number the better. Generally, you should look at the condensation resistance number ( CR number) when looking at Ufactor..the CR number should be 57 or higher. The reason i bring this up is because some companies may show an. " R5 window" with only double pane glass. The only way they can do that is by adding a Hard Coat lowE on the inner pane of glass. This will dramatically lower the condensation resistance ( CR ) number into the 40's; not a good thing which is why most companies refuse to offer that glass package.
In the northeast, a solar heat gain of .25 - .30 is optimal.
Ufactor- .28 or lower.
Ufactor just measures how much heat escapes through the window in the winter months: the lower the number the better. Generally, you should look at the condensation resistance number ( CR number) when looking at Ufactor..the CR number should be 57 or higher. The reason i bring this up is because some companies may show an. " R5 window" with only double pane glass. The only way they can do that is by adding a Hard Coat lowE on the inner pane of glass. This will dramatically lower the condensation resistance ( CR ) number into the 40's; not a good thing which is why most companies refuse to offer that glass package.
Last edited by masterext on Wed Jul 16, 2014 7:51 am, edited 1 time in total.
- Windows on Washington
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Re: How to test thermal and solar heat transfer
You will still feel some heat depending the glass package that was specified. In the NE, you still want somewhere near a SHGC of 0.30 in a double pane window.
Re: How to test thermal and solar heat transfer
Thanks for the replies. I guess I asked the question in the wrong way.
What I want to do is look at the specs for the windows and then do a "home test" to determine if they are actually anywhere close to the specs. Having to close the curtains in the summer when the sun rays are striking the window glass, just to keep a room cool kinda defeats my intended purpose for changing them out. The old ones were fogged up between the glasses and hot. Now the new ones are not fogged up but I have to shut the curtains and can't see out or have natural light come in...
I have Softlite Bainbridge Low-E argon glass package with intercept spacer.
What I want to do is look at the specs for the windows and then do a "home test" to determine if they are actually anywhere close to the specs. Having to close the curtains in the summer when the sun rays are striking the window glass, just to keep a room cool kinda defeats my intended purpose for changing them out. The old ones were fogged up between the glasses and hot. Now the new ones are not fogged up but I have to shut the curtains and can't see out or have natural light come in...
I have Softlite Bainbridge Low-E argon glass package with intercept spacer.
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Re: How to test thermal and solar heat transfer
There is no real test that you can do at home to assign or verify a value like the SHGC.
You can check for the presence of Low-e via the match test but that isn't very specific in nature.
You can check for the presence of Low-e via the match test but that isn't very specific in nature.
Re: How to test thermal and solar heat transfer
Are these west-facing windows?
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Re: How to test thermal and solar heat transfer
Uh oh.....Oberon is here.Oberon wrote:Are these west-facing windows?
Prepare for the glass discussion to go full nerd.
You know I love you Oberon 1 Kenobi.
Re: How to test thermal and solar heat transfer
Windows on Washington wrote:Uh oh.....Oberon is here.Oberon wrote:Are these west-facing windows?
Prepare for the glass discussion to go full nerd.
You know I love you Oberon 1 Kenobi.
only if we let it get away from us.