I'd consider a window with Cardinal's LoE 179 and i80 glass combo. COG U-factor of .26 and a SHG of .59.

I agree with sky, with one minor change. Cardinal is replacing 178 and 179 with LoE 180.

LoE 180 has an advertised COG of VT .80, U .24, and SHGC .69

The quote I received today stated a U-Value of .29 and SHCG of .38. This is for LoE argon-filled glass with super spacers.

I guess thinking about my home more, I am more concerned about reflecting heat back into the home in the winter, rather than solar heat gain. More of my windows face north and the old windows I have now just seem to radiate cold into the room and I want to eliminate that as much as possible.

Do you think the numbers posted above would be good for my situation? I did not ask the glass company about the Cardinal LoE 180 yet, but if you think it would be better for my situation, I could see if they can make a comparison quote, assuming they carry the Cardinal bran.d

Who is the window company?

I would lean towards the higher SHGC (whatever coating) on the south side and the lower U value on the other three sides.

I agree. That's the way I would recommend doing it.

The window company is Hellenbrand glass out of Waunakee, WI. Not sure of the brand of window, but I can check on that. Thanks for the help. So, my original thinking was correct then, right?

Yep, I think you have the right idea...

And from the company website: "Our strong position in the window and door industry allows us to buy products directly from the manufacturer. This includes wood or wood clad windows and doors by Marvin, Integrity by Marvin, Loewen and Lincoln. We also offer aluminum and vinyl products such as Traco, Gerkin, Lindsay, Silverline, and Quaker."

Some of those companies will offer the option of mixing different LowE coatings and some won't. Are you leaning toward a particular company or product?

While I don't comment on specific companies, Sky is very knowledgeable and is a great resource if you have questions about one company vs another...assuming that a company salesman has talked with you about options and about the specific companies that would lead to questions.

Great. Thank you again sky and oberon. I am checking on the brand of windows the dealer is using in his quote and will post back later.

Okay, follow-up. Here's the glass saleman's response to my questions:

For brand of windows, he said - "These are just manufactured thermopanes. The manufacturer has a 10 year seal failure warranty on them. I would more than likely get them from a place called Everclear (based out of Wausau)."

For ordering windows with a higher SHGC on my south-facing windows only he said, "If that is what you would want, then I would probably just order the South side with no coating at all. Just clear on clear. Then the SHCG is .76.

Any thoughts or opinions on his answers?

I disagree with ordering them without loE glass. I think you should have a U-factor below .29 which is obtainable with a single coat LoE. Sounds to me like the salesman is acting like a jerk.

Here is a link that might be useful: Cardinal LoE i81

plus 1 with sky

Since I am replacing the window glass only, it does not look like Cardinal is an option for me. Again, I appreciate everyone's help in working through my decisions. This is more complicated than I thought it would be!

Another window company in Madison responded to me with the following info. "We do not have access to Cardinal direct. They only supply in bulk quantities to large window manufacturers. However, the glass I quoted you was Guardian RLE 71/38. If you did the Argon add on, it would drop you down to .24. It does not, however, affect the SHGC. That will still be .38. Your percent of visible light transference is 71, and your fading transmission is at .33. Hope this helps. Please let me know if there is anything more we can do for you."

Thoughts on the above?

One more update. Hellenbrand came back and said they can get Cardinal 180 from one of their suppliers, and that it's $1.25 per sqft less than the original quote.

So, is Cardinal 180 a good glass to go with for all of my windows then?

No. I would only use it on the south facing elevations and use at least the LOE-270 on the rest. Might even want to consider triple pane on the north, west and east elevations IF you can get it for the right price. If not, you might still want to consider TP on the north side.

Thanks. I am seeing if I can get quotes on Cardinal LoE-270 w/ LoE-i81 then LoE-270 only, so I can compare the costs.

Another update:

I asked for a quote on Cardinal LoE-270 w/ LoE-i81 then LoE-270 only and this was the response from their supplier:

"I sent a price request to my supplier and he thinks you will have an issue with heat build-up breaking the glass, so he is getting me a quote using loe3-366 and the specs on that. I just sent him an email, so hopefully he gets back to me shortly."

Does this thinking make sense? I think specs on loe-366 seem appropriate for my north windows for double pane (SHGC: 0.27 / U-FACTOR: 0.24 / TDW: 0.43 / LIGHT TRANS: 66%)

If the supplier really said that then he doesn't have much of a clue about windows.

Keep in mind those numbers are glass only. Once you put them in a window the SHGC will drop below .20 the U-factor will go up to around .29 and the VT will go to around .45.
The 366 will be fine for north windows as long as you understand you will lose some Visible light. Have you actually seen a sample of an IG using these different types of glass? If not, I would suggest you do so just so you know exactly what you are getting.

The window company will bring the various glass types when they come to measure my windows. Still not clear on why his supplier said the LoE 270 could break, but I'll try and get clarification on that.

So, the salesman said, "that the possibility of the glass breaking due to heat buildup was originally you wanted me to check on both lights having LoE 270 on them. If just 1 light has LoE, then there won�t be any problems."

I did look at glass samples, and I am okay with the 366 being slightly darker, so 366 should actually be better than the other Cardinal choices for my north windows, correct? For my south windows, he quoted Low-E 181. I can't find any specs on that, but I believe they have a higher SHGC.

ranger,

A bit of clarification...

Cardinal currently has three versions of HSHG coatings - LoE-178, LoE-179, and LoE-180. LoE-178 and LoE-179 are being phased out and LoE-180 will be Cardinal's only HSHG offering in the very near future (I believe that 178 may no longer be available).

LoE-180 has a SHGC of .69, a .24 U-value, and VT of 80% when used on surface 3 of a dual pane IGU (3mm glass). But keep in mind that these numbers are for glass only and they will be different when the glass is installed in a window system.

The LoE-180 is a single-silver softcoat and as a softcoat it has to be installed between the lites of an IG - it cannot be exposed or it will corrode and fail.

LoE2-270, LoE2-272, and LoE3-366 are also softcoats, but 270 and 272 are considered moderate solar heat gain and 366 is considered low solar heat gain. Coatings 270 and 272 have two layers of silver and 366 has three layers of silver in the coating. Notice a pattern here?

LoE-180, 270, 272, and 366 have to be installed inside an IG to protect the coating.

Recently Cardinal introduced LoE-I81 which is a hybrid between soft and hard coatings. It has softcoat performance but can be used in traditional hardcoat applications.

LoE-I81 is designed to be used as a surface 4 coating. Surface 4 is the glass surface that you can touch inside your home. LoE-I81 is designed to be used in conjunction with a softcoat on IGU surface 2.

In an IGU, in combination with (for example) LoE3-366 on surface 2, and with argon gas infill, the IG will have a .20 U-value. A .20 U-value is more indicative of triple pane performance with Low-E coatings on two surfaces than with a typical dual pane. The intent of I81 is to increase U-value performance in dual pane IGU's to near triple pane U-value performance levels.

Using LoE-180 on surface 3 and I81 on surface 4 would be a dream for the combination of HSHG and low U-value, but that make up is not currently avaiable (technical challenges), so in order to have I81 on surface 4, surface 3 will not be coated.

On your southern exposure, if you want the maximum solar heat gain available while still using a Low-E coating, then you want to use LoE-180 on surface 3.

For the other windows in your home using LoE3-366 on surface 2 and I81 on surface 4 will result in the highest glass U-value performance numbers currently available in the industry. You can also specify LoE2-270 or 272, but the U-value will drop off a little bit when compared with LoE3-366.

And one final point of clarification - Cardinal's Low-E nomenclature will tell you the number of layers of silver in the coating and the VT of the coating in an IG unit consisting of two layers of 3mm glass with one glass lite coated. So, LoE-180 has one layer of silver and 80% VT. LoE�-366 has three layers of silver and 66% VT. Also the "2" in LoE2 is really supposed to be LoE "squared" and the 3 in LoE3 is supposed to be "cubed", but THS doesn't allow superscripting.

Okay, it sure gets confusing, but I do think I get it. I am going to ask him to quote exactly what you stated below and see what happens.

"For the other windows in your home using LoE3-366 on surface 2 and I81 on surface 4 will result in the highest glass U-value performance numbers currently available in the industry. You can also specify LoE2-270 or 272, but the U-value will drop off a little bit when compared with LoE3-366."

Okay, got him quoting on the LoE3-366 w/ I81. He mentioned that this is the glass that needs to be heat-treated. Curious to see how this glass changes the cost from just using LoE3-366 only.

I am in process of ordering new windows. Front of my home is south facing and I live in Chicago. I am curious if it's worth while to request High Solar Heat Gain coating for the south facing windows? My concern is that I may be able to cut heating costs but my cooling costs would go up as well. I ran a few scenarios using the calculator on Energy Star website and noted minimal costs savings between multiple coating options.

Thank you

Overall you would benefit by using high solar gain windows on the south face (assuming that they get good sun and are not blocked by trees, etc). You can mitigate the loss in summer by keeping the shades down when the AC is on ;).

Homesealed. - thank you. Boy do I feel stupid for not thinking about shade during summer. There are some trees but overall I feel like southern sun will provide lots of warmth.

Very interesting and educational thread. Even an old dog can keep learning a thing or two.

+1

In Chicagoland, high SHGC on the South facing walls. Even more beneficial is if you have some good thermal mass inside the rooms of those South facing windows.

Standard Low-e will block a bunch of heat by comparison so don't worry about sweating in the summer.

If you haven't picked a contractor, Window4U is out of Chicago and does a fantastic job.