Window U-Value - Contractor Talk - Professional Construction and Remodeling Forum

Home Serve · 05-29-2008, 08:49 PM

What is the U-Value of the windows that you are installing?
We are installing double pane with a U-Value of .19
Do you know of some documentation or charts or something that shows the savings of a high quality, low U-Value window over a typical .32 U-Value??
Ours retail for about 4.25 per United Inch.
I sell below retail some most of the time.
What are your windows like to compare??
Thanks,
Dave

dougchips · 05-29-2008, 08:55 PM

Someone is BSing you, to the best of my knowledge a .19 can not happen with a double pane.

I think around a .29 or .30 is as good as it get for a double pane window. Triple panes range from .24 down to .16.

Patrick · 05-29-2008, 09:04 PM

Quote:

Originally Posted by dougchips

Someone is BSing you, to the best of my knowledge a .19 can not happen with a double pane.

I think around a .29 or .30 is as good as it get for a double pane window. Triple panes range from .24 down to .16.

Agree, But lets remember U value is going to change based on the size of the window, but no way can i imagine .19 on a double pane. Anyone know off hand what double low e adds, and also the comparison of krypton vs argon

Also remember the U value is only as good as the walls around the window. I love when people in old uninsulated farm type houses are all concerned about U factor

Home Serve · 05-29-2008, 09:26 PM

Quote:

Originally Posted by dougchips

Someone is BSing you, to the best of my knowledge a .19 can not happen with a double pane.

I think around a .29 or .30 is as good as it get for a double pane window. Triple panes range from .24 down to .16.

You are right, my mistake. The literature was a little misleading because it compares window .19 to windows that are .32
Our windows are actually .30 not .19

On same subject it does say that testing done on a single story home in International Falls, MN with a basement, gas furnace, A/C and 300 sq ft of window area resulted in the following determination:

Every .01 U-value improvement in the windows resulted in a reduction of approx. 400 lbs of CO2 and an energy savings of approx. 50.00 annually.

Over next 20 years with 5% annual increase in utility rates:

Comparing U-value of .19 versus .32
period savings
5 years 3,591.66
10 years 8,175.63
15 years 14,026.07
20 years 21,492.87

I thought this pretty interesting as I never guessed that there would be this much difference.

A house that we are doing here in MO has 540 sq feet of glass in it. We are doing 21 of the windows this year.
Dave

dougchips · 05-29-2008, 09:59 PM

Dave, the triple pane also saves on cooling bills. With two layers of low e they can block out 95+% of harmful UV rays that fade carpet, furniture and window coverings.

In theory they make your furnace and cooling units cycle on less and provide them with a longer service life.

**Ed the Roofer** · 05-29-2008, 10:06 PM

Please provide a Link to any of that U-Value and Savings information so that I could learn a little bit more about windows.

Ed

Home Serve · 05-29-2008, 10:19 PM

Doug, The windows we have you can get both panes with Low E but I don't know what kind of savings that would offer people in this area. I sell them one pane low E. I should find out in order to compare but I have not seen the testing data done on both panes low E. I have a general opinion that triple pane is not worth the extra $$ in our climate at this point in time.

Ed testing info: by Tru-Seal Technologies using RESFEN 5.0, a computer program which is the industry standard for calculating the heating and colling energy performance of windows.
That's all I have except a question to my window company as to why they compared .19 windows when theirs are .30
Why would I want to offer that information to my customer unless I am selling .19 windows? And it's cold in International Falls so would have to change the data for St Louis area. I can fax you the sheet if you want to PM a fax # or such.
Dave

Patrick · 05-29-2008, 10:26 PM

Quote:

Originally Posted by Ed the Roofer

Please provide a Link to any of that U-Value and Savings information so that I could learn a little bit more about windows.

Ed

Hey Ed, Sorry I did NOT forget about you... I have been very busy, I will get something out to you in the next few days

dougchips · 05-29-2008, 10:28 PM

Quote:

Originally Posted by Home Serve

Doug, The windows we have you can get both panes with Low E but I don't know what kind of savings that would offer people in this area. I sell them one pane low E. I should find out in order to compare but I have not seen the testing data done on both panes low E. I have a general opinion that triple pane is not worth the extra $$ in our climate at this point in time.

Ed testing info: by Tru-Seal Technologies using RESFEN 5.0, a computer program which is the industry standard for calculating the heating and colling energy performance of windows.
That's all I have except a question to my window company as to why they compared .19 windows when theirs are .30
Why would I want to offer that information to my customer unless I am selling .19 windows? And it's cold in International Falls so would have to change the data for St Louis area. I can fax you the sheet if you want to PM a fax # or such.
Dave

You can download the RESFEN program for free, however it is not easy to use.

**Ed the Roofer** · 05-29-2008, 10:32 PM

I found a couple of things on my own so far in the past minute.

Are these any good with accurate information?

Ed

http://www.efficientwindows.org/code.cfm

and this one

http://64.233.167.104/search?q=cache...lnk&cd=4&gl=us

dougchips · 05-29-2008, 10:39 PM

Quote:

Originally Posted by Ed the Roofer

I found a couple of things on my own so far in the past minute.

Are these any good with accurate information?

Ed

http://www.efficientwindows.org/code.cfm

and this one

http://64.233.167.104/search?q=cache...lnk&cd=4&gl=us

The first site is a must read for you Ed. Also learn to use the NFRC site. Between the two you will get enough knowledge to put anyone asleep.

Home Serve · 05-29-2008, 10:42 PM

Quote:

Originally Posted by dougchips

You can download the RESFEN program for free, however it is not easy to use.

I guess I spend too much time out in the field and probably should be spending more time and energy on some research and information that would be helpful to our customers. It's hard to get time to do stuff like that with taxes and other have to book work. I do give a lot of thought at the time of the sale as to the particular situation the person is in to figure out what I think the best answer for their problem is. I try not to sell a person more or less than they need. Shoot straight with them but don't cut corners on quality. More research and info would help with that however.
Dave

**Ed the Roofer** · 05-29-2008, 10:49 PM

There are all sorts of Free DownLoads available at this site.

If it doesn't work, since I had to sign up, back off the last few characters down to the .Gov to get to the main site and register.

http://windows.lbl.gov/software/default.htm

Ed

easy sider · 05-30-2008, 02:17 AM

Any window manufacterer can claim anything they want , thats why windows are rated by the NFRC.

Clear insulated glass has a r value of r-2, adding low emisity gains r- .86 to r-2.86 and adding argon gas makes the window exceed Energy Star at r-3.23. The higher the r value the lower the u value.

Jake Stevens · 05-31-2008, 08:38 AM

We use a window from Lockheed Corp. thats a U.29 with Low "E" and Argon. I think that is about the best you're going to get. I do know that one company, Paradigm likes to show there testing with the center of glass which is not true testing. But with all windows its installation that makes the difference.

Home Serve · 05-31-2008, 02:58 PM

Quote:

Originally Posted by Jake Stevens

We use a window from Lockheed Corp. thats a U.29 with Low "E" and Argon. I think that is about the best you're going to get. I do know that one company, Paradigm likes to show there testing with the center of glass which is not true testing. But with all windows its installation that makes the difference.

Jake,

What is it you mean "testing the center of the glass"? Never heard of that. If we go by NFRC ratings they test all windows the same manner.
What do you do at the installation to insure an efficient installation?
Dave

Patrick · 05-31-2008, 05:59 PM

Quote:

Originally Posted by Jake Stevens

We use a window from Lockheed Corp. thats a U.29 with Low "E" and Argon. I think that is about the best you're going to get. I do know that one company, Paradigm likes to show there testing with the center of glass which is not true testing. But with all windows its installation that makes the difference.

I thought Deschaine was the exclusive paradigm dealer up your way

easy sider · 06-01-2008, 03:07 PM

Quote:

Originally Posted by Home Serve

Jake,

What is it you mean "testing the center of the glass"? Never heard of that. If we go by NFRC ratings they test all windows the same manner.
What do you do at the installation to insure an efficient installation?
Dave

Window manufacturers some times test the center of a window instead of the top because argon gas settles to the bottom of the sealed unit. Argon is heavier than air and will push air to the top of a sealed unit. The argon measurement for the top of the unit has to be with in a certain percentage of the bottom. This is usually done at the manufacturing facility where the same sealed unit is rated over time and measurements documented to meet NFRC requirements.

dougchips · 06-01-2008, 08:46 PM

Quote:

Originally Posted by Home Serve

Jake,

What is it you mean "testing the center of the glass"? Never heard of that. If we go by NFRC ratings they test all windows the same manner.
What do you do at the installation to insure an efficient installation?
Dave

When people talk about "R-9" they are talking about the center of the glass. It's sort of cheating to talk about center of glass ratings since the center is not a reflection of the whole glass unit and frame.

easy sider · 06-02-2008, 01:02 AM

Quote:

Originally Posted by dougchips

When people talk about "R-9" they are talking about the center of the glass. It's sort of cheating to talk about center of glass ratings since the center is not a reflection of the whole glass unit and frame.

The sealed unit is measured top, center and bottom for argon gas and these measurements are allowed a percentage difference since the argon will settle to the bottom of the sealed unit.

I have not heard of "R-9" , what is this about ? Any window with a NFRC rating is tested in the same manner to determind R and U values as well as heat gain. A sealed unit made in a window shop and not a factory may not have the NFRC rating.