@oberon

I don't see why LoE-2 wouldn't meet the code requirement. I would ask why doesn't LoE-2 meet the requirement in Portland, OR, because I am sure it does. I would never choose a LoE-3 level for Portland, OR - never. LoE-366 is for climates like Arizona, New Mexico, and similar, that get an enormous amount of sun.

If I was building in Portland and I had a bunch of south facing windows with "generous" (30" or better?) overhangs, I 100% would opt for LoE-180 on surface 2 and I89 on surface 4. With argon fill in that glass make-up you have a CoG U factor .21, VT 77%, and something a bit lower than SHGC .62.

Keeping in mind that window performance numbers will not be as good as CoG numbers, they should still easily meet code requirement and still leave you with as good a VT as you can get in a coated glass window.

Since you mention that you aren't looking for high solar heat gain, I would suggest that it's not like you are inundated with an overabundance of unwanted bright sunny days during a typical Portland winter, and perhaps a little extra warmth when the sun is out might not be so bad?

But it's also true that 180 coating on surface 2 will result in lower SHG than if it was on surface 3 (the .62 above is surface 3), and since your overhangs (if sufficiently generous), should do quite well at shading your windows in summer when the sun is high in the sky, you should have no issues with excess solar heat gain during the parts of the year when it's not welcome.

Per Alpen, maybe your contractor is concerned with using ZR-6 because of the suspended film technology used in the manufacture of the IG unit? Personally I have no problem with Alpen suspended film performance, but I do understand if that's the reason for his hesitation given the history of the product. Alpen history exempted.

That said, I do think that ZR-6 is over-kill in your climate, but certainly not unheard of.

Personally I wouldn't use 366 in Portland, and if you don't want to use 180, then ask for 272. If it doesn't meet code then add the I89 on surface 4 and you will be fine, but less VT than you will get with 180.

@M Miller, @oberon476, thank you for your thoughts, and I'm glad that I'm not alone in thinking that E366/i89 is complete overkill for Portland. And yes, our overhangs over the south windows range from 5' to 12' deep, so we are pretty well shaded during the summer. I really don't want dark windows in Portland, it's gloomy enough as it is.

I'm looking at the Cardinal glass table, and see the options that @oberon476 mentioned above (posting the figure below):

So indeed, the U factors for E366/i89 and E180/i89 seem nearly identical (0.20 vs 0.21), while the difference in SHGC and VLT is significant.

The problem is that as stated, these numbers are for the glass, not for the window, and I can't find a data source for the complete window. My window dealer says that with Marvin Essential, E366/i89 (basically Low E3/ERS) is the only way to meet the 0.27 requirement; once we step away from E3, we end up at 0.28. He also says that Essential is not available in E272. I don't know how to verify what he says.

What's also odd is that looking at the dealer's quote, he shows the E366/i89 as having U = 0.26, SHGC = 0.19, and VLT = 0.43. I don't understand why the latter two differ so much from the Cardinal numbers of SHGC = 0.27 and VLT = 63% - I would have guessed that those properties don't change when the glass is installed in the frame?

What's also strange is that when I go to the NFRC database and find Marvin Essential, sure enough to get a U of 0.26, we end up with SHGC of 0.19 and VLT of 43% - https://search.nfrc.org/search/cpd/cpd_search_detail.aspx?cpdnum=MAR-N-377-00514-00001

Are Marvin Essential such leaky windows that I can't meet 0.27 without darkening them with all these coatings?

@oberon476 I saw a notification that you posted a comment starting with "The reason for the differences is that Cardinal is posting glass numbers while Marvin is posting window numbers.
Imagine two identically sized window... ," but I don't see the comment here.

In the meantime, I received this list of window options for Marvin Essential from our dealer, it does look like only the Low E3/ERS option would meet the OR code of < 0.27.

Yep, unfortunately I was in a hurry at the time and I meant to edit something (grammar) and hit delete...then I said a number of words that I wouldn't want to post in here, but didn't have the opportunity at the time to repost it..

For the same reason I can't post a longer reply at the moment, but will be back a little later and follow up..

Unless I am missing something and you interpolate the dealer's numbers. the Lowe 272 should give you a .26 and the Lowe180 a .27 with the addition of the ERS to surface 4. Correct me if I am wrong, oberon. This should be verified by the dealer before ordering.

U factor, VT, and SHGC are all based on entire window and not just glass performance. The way to look at it is to imagine two windows that are identical size and using identical glass package, but window A is 15% frame to 85% glass while window B is 25% frame to 75% glass.

If windows were rated by the glass alone then the two windows would have the same VT and SHGC, but windows are rated based on the entire unit that is filling the hole in the wall, and in that case the window with the larger glass area is going to have a higher VT and a higher SHGC rating than will the window with less glass area, but also the window ratings, regardless of glass area, are going to have lower VT and SHGC ratings. Adding grids will lower those performance numbers even more.

Not sure where your dealer got the idea that 272 isn't available in the Essential line, because it is. You can find performance examples on the NFRC site.

Are Marvin Essential such leaky windows that I can't meet 0.27 without darkening them with all these coatings?

You are kind of confusing air infiltration (leaky) and SHGC (darkening) with U factor. While U factor does improve as more silver layers are added to the coating (180 = 1 layer, 272 = 2 layers, 366 - 3 layers), both U factor and SHGC are lowered. Adding additional layers to the coating does result in a darker coating which is good for lowering the SGHC, but darkening has nothing to do with the improvement in U factor. And while air infiltration is a very important part of window performance, it's a separate measurement rating than U factor.

I agree with EastBay that adding 4th surface coating should bring the U factor to ,26 for 272 and .27 for 180. I have no idea why your dealer seems to be so resistant to using other coatings than 366, other than it might be easier (in their minds) to make everything 366 and no worries.

Honestly in your climate the difference of a few hundredth's is insignificant and you would never notice it in comfort or $$, but codes are codes.

I would push harder to get better numbers from the dealer. You need to get the numbers for 180 (my choice) and 272 with surface 4 coating before making a final decision.

Also not a fan of the VT numbers given in the chart from your dealer that you posted. The numbers don't make sense to me in an apples to apples comparison.

@eastbay10 the Lowe 272 should give you a .26 and the Lowe180 a .27 with the addition of the ERS to surface 4.

Thank you for the suggestion, that sounds like both 272 and 180 with i89 are promising options (and that makes sense since on the Cardinal site the three glass units have U factor of about 0.02 apart).

I'm not sure how to get this confirmed through Marvin - they don't seem to have a consumer contact portal, so I have to go through my dealer, who said that Marvin Essential does not make 272.

@oberon476 U factor, VT, and SHGC are all based on entire window and not just glass performance

Thank you - I was aware of this for the U factor, but not SHGC or VLT. So to really assess the light transmission, I should look at the glass properties, not window properties, right? After all, I won't be looking outside through the frame any more than I'd be looking outside through the wall.

Not sure where your dealer got the idea that 272 isn't available in the Essential line, because it is. You can find performance examples on the NFRC site.

Can you help me decipher the NFRC site? I found these Marvin options, and I see a bunch of units that meet the < 0.27 requirement, but I can't tell which coatings they are using. Is there a decoder ring to tell which are 180, 272, etc?

https://search.nfrc.org/search/cpd/cpd_energyStar_search_detail.aspx?cpdnum=MAR-N-375&energyStarVersion=6

And again, if there is a way for a mere mortal consumer to get this info from Marvin, please let me know - I hate to be at the mercy of the dealer, especially if (as you say) he is wrong.

And just to make sure I understand - the reason you would not recommend going with 366 in Portland is the reduced VLT, not some other reason, right?

Marvin Essential does not make 272.

Below are copies of two Marvin Essential options from NFRC directory. The first one is 366 with I89 on surface 4. The second is 272 without surface 4 coating.

Look where is says LowE on the first one - 0.02 is 366 and 0.149 is the i89. LoE 180 is 0.068.

Now look at the second one, 0.042 is 272. Notice U factor for the 272 is .28 without the surface 4 coating. 366 without i89 is U.27, so i89 improves U by .04 in this example. A comparable improvement to 272 would be U .24.

It took me less than 30 seconds to find the 272 example because it's common under the essential listings. LoE 180 is 0.068, but I didn't include an example.

I was aware of this for the U factor, but not SHGC or VLT. So to really assess the light transmission, I should look at the glass properties, not window properties, right? After all, I won't be looking outside through the frame any more than I'd be looking outside through the wall.

For looking for VT while looking out the window use the glass VT, but when considering how much overall light enters the room use the window VT.

And just to make sure I understand - the reason you would not recommend going with 366 in Portland is the reduced VLT, not some other reason, right?

Yep, that is the only reason.

@oberon476

0.02 is 366 and 0.149 is the i89. LoE 180 is 0.068. ... 0.042 is 272.

OMG, THANK YOU for providing the decoder ring, this is the info I was looking for!

Notice U factor for the 272 is .28 without the surface 4 coating. 366 without i89 is U.27, so i89 improves U by .04 in this example. A comparable improvement to 272 would be U .24.

That makes complete sense to me.

So it looks like I can get the 272 windows, which would meet code with the i89. And I guess 180 would too, after the i89 added:

For that one they're putting the e-coating on surface 3 instead of surface 2 like they did for 272 - is that normal for 180? edited - I just read your post "Getting the Right Low-E Window Coating" on GBA where you said that 180 is usually applied to surface 3, so that explains that!

Is it possible that Marvin does not supply 272 or 180 glass with the i89 option? I just can't believe that my dealer is that poorly informed. It would be really helpful if I could find a CPD number with the 180 or 272 with i89, so that I can share it with him.

I can do the research myself, if I can find a way to search the NFRC database by specifying which coatings I'm interested in, instead of rummaging through 30 pages of results where I have to click on each one to see what coatings they are using. Is there a way to do that?

Normally 180 is applied to surface 3, because that's how you get the maximum SHGC, but U and VT don't care if it's on surface 2 or 3, makes no difference in performance to them.

The IG units that Marvin uses come from Cardinal and Cardinal has no problem at all with building whatever IG configuration that Marvin or any other window company wants to order, with provision that there are some IGU configurations that might not be a particularly good idea, but that only means that Cardinal will chat with the window company about other possible options that make more sense, but if the window company really wants it then they will provide it as long as it can be done.

Using either 272 or 180 with I89 is not a problem at all, in fact Cardinal even developed a special version of 180 + i89 specifically for Canadian window companies for increased solar gain applications and 272 with i89 is a very common makeup.

Thank you so much Greg! I certainly trust your knowledge more than the window dealer I'm working with. Thanks to your responses, I was able to convince the dealer to send an email to Marvin to ask about availability of 272 with i89. We'll see what he comes back with.

Well my optimism didn't last long. The second dealer who contacted Marvin got back to me and said that Marvin won't do a 272/i89 or 180/i89 combo, only 366/i89. I chatted with him quite a bit, and he said that yes, Cardinal does make that combo, but Marvin won't sell it, because they have not certified or tested it in their windows.

So I think I'll have to accept the 366/i89 in Marvin, or else go to a different manufacturer, which I'm not sure I want to start doing at this point.

That’s ridiculous, i can’t believe that of marvin. Frankly in many years in the industry, this is the first time that i have ever heard of marvin saying no to a very reasonable customer product request.

It also makes no sense since they shoild be able to simulate the performance results, there are programs for that, and they don’t have to physically test or certify their windows just to add i89 to the glass package,

Agreed, but it seems like it is what it is with Marvin. I'll see if I can get a quote from Alpen, but I'm also reaching the point of where we need to decide pretty soon on what windows to get.

Are you okay with vinyl? Consider looking north to a company called Innotech and south to a company called Anlin. Innotech offers tilt turn windows and that may not be what you want, but might be worth a look. Both companies make very high quality vinyl windows and are worth looking at.

If you want fiberglass or other composite you might also check out Kolbe. They offer Forgent which is a fiberglass hybrid. There's also Enerlux, a fiberglass manufacturer in Missouri that might be worth a look.

All of these companies use Cardinal glass, and mostly IGU's as well, so you wouldn't have to learn more glass names and performance values.

I am really puzzled about Marvin because in my experience they have always been a company that prided itself on giving the customer what they want....this seems way out of character for them. Perhaps it's the new generation taking over the business...literally.

I'm very familiar with Innotech, we got a quote from them for the first house design, when we were going to go with tilt and turn (although we settled on Kneer Sud). For this iteration, we decided against TnT, and we really like the thin profile of Marvin - first the Modern line, and then, after getting sticker shock, the Essential.

I'll definitely have a look at the other names you mentioned, thank you for that. But to be honest, with all the other fights I'm fighting (fire marshal just told us we need to have a full house sprinkler system, ka-ching), I may just capitulate on this and take the VLT hit, Not ideal, but we've long gone away from wanting the perfect house, and are just hoping to get a "good enough" house :).

"[Marvin will do} only 366/i89"

I think the issue here is that you are in Portland, OR, but trying to get windows that would suit the conditions in New Mexico. I don't understand why you don't simplify, stop ultra-customizing, and simply get Marvin's standard 272, which is how they sell them without having to do customization. It will meet code. Marvin sells these all day long throughout the PNW.

Because 272 doesn't meet code of U < 0.27.

That's the fundamental problem - to meet Oregon code requirement, we end up with a window more suited for Arizona.

Window shopping was a similar experience for us. We're near Seattle and really wanted the Marvin modern before getting sticker shock. Also got quoted the same glass package. I wanted less leaky windows than the essentials, so we ended up going with westeck vinyl windows and have 272 glass to meet code I believe. Good luck!

I am biased because I have Innotech windows and after 17 years they look and operate almost like brand new, so I am obviously a fan.

I also understand your frustration. Some codes simply make no sense, IMO. I think it may come down to simply lower U good, higher U bad, so we want lower U no matter what it takes to get there. Simply not understanding the specifics of what it might take to get what they want because they don't really understand all the potential factors involved.

Also and simply curious about why did you prefer the 272 option to 180 since 180 had better VT with only .01 difference in U factor?

Thanks for the suggestions, I'm checking them out. The Kolbe Forgent seems to have a number of options that would meet the 0.27 or lower requirement. I can go with either 270 by itself, or 270 with ThermaPlus (i89, I guess).

It's interesting that the two 270 options that meet code don't offer much improvement in terms of VLT over the low E3 Marvin windows - Kolbe is 0.47, Marvin is 0.43.

I'll try to get a set of these priced. How does Kolbe compare to Marvin in terms of quality and reliability?

Not sure why it used that old user name, it's still me (the thread starter).

Remember that VT is based on whole window and not just the glass, so the difference you are seeing is in part due to different percentage of glazing versus sash and frame.

That's a good reminder. It looks like the frame width is within an 1/8" of each other in the two windows I'm looking at.

The point I was trying to make was that there is not much of a difference between the Kolbe 272/i89 option and the Marvin 366/i89 option, we're talking 47% vs 43%. And that seems to be consistent with the glass unit difference between the two: Cardinal lists VLT for 272/i89 as 70%, and for 366/i89 as 63%.

I was hoping to find a Kolbe option of 180/i89 or 272 by itself that meets the U factor requirement, but I don't see that combination that on their site.

Given that Kolbe is right up there with Marvin in terms of quality, I'll certainly try to get a quote for it.

Thanks @oberon476!

You're welcome, and I would go ahead and ask Kolbe about the 180/i89 option to see what they say. Couldn't hurt. I really like Kolbe, I have been in their main factory many times.

Typically window companies that off 270 don't offer 272 and vice versa. Most companies offer the 272, I thought Kolbe did in fact and was surprised by 270.

I'll ask them about that option, for sure.

@pgjs we ended up going with westeck vinyl windows and have 272 glass to meet code I believe.

I just spoke to Westeck, they were very helpful and said that they can most likely meet the code requirement with just a 270 Low E2 coating, no additional coatings needed. They're preparing a quote for me as we speak.

Any concerns about their quality or responsiveness? Some reviews I read seem less than stellar.

I unfortunately can't offer much insight into the process yet. We're starting our renovation at the end of the year and haven't ordered yet.

Here's my long ramble on how I decided. I started off asking for quotes for Andersen 100s and E series and Marvin essentials and modern. After going to see them in person, I really wanted slim profile fiberglass/aluminum, so I wrote off the Andersens, but then got sticker shock with the moderns and didn't love the low E3/ERS glass that I needed to hit my U values with either Marvin. Getting details was also difficult.

Unfortunately, none of the commonly recommended vinyl windows are in my area. My builder suggested Westeck and had some good experiences with them. I also tried hard to get a quote from Cascadia fiberglass, but they are more focused on commercial property, so nothing came of it. I went to see Westeck windows at their showroom and was happy with how they looked and their communication thus far. Price was also good, so I'm going with my builder's recommendation.

Thanks for that ramble, it's very helpful!

I'm waiting for a quote from Westeck to see how it compares to Marvin. I'm still a bit concerned by lack of clear feedback about their quality, but maybe I'm too paranoid.

I also had a nice chat with a PNW rep for Kolbe (already a bonus since Marvin has no such contact as far as I can tell). She said that they can definitely provide packages to meet U < 0.27, either with 272 or 180. She also mentioned that the code does not require that every window be below 0.27, just that the average needs to meet < 0.27. That was news to me, and something that our architect or Marvin dealers did not mention. So I checked the code, and confirmed that she's correct. So that means that we can put 180 windows with U= 0.28 in areas where VLT is important to us, and maybe 272/i89 with U=0.26 in other areas like bathrooms or north facing windows, so that it works out to an average of 0.27.

I hope that between Westeck and Kolbe we can figure out a good plan, I'd love to be done with this aspect of the build.

Tupi2020, did you decide to go with Westeck or Kolbe and have you been happy with your choice?

I was going to go with Kolbe, they were able to provide the windows in the combination that I wanted, unlike Marvin.

But unfortunately we had to throw in the towel on the whole build project, and ended up buying an existing home. That's one way to solve the window dilemma, right? :)

Oh wow - congrats! :)

Thank you, it's nice to be done with the stress of all that design work!

Sorry I didn't reply to Westek, I totally missed your post on that one, but I couldn't have offered much at all since I don't know very much about them.

The whole building process can be crazy stressful, it can be a lot less so buying an existing home for sure.

Congrats and hope it works all the best for you

Thanks Greg! It's not the dream home we had planned, but it is beautiful and full of character, and no more dealing with architects and builders! I think I was would have had a heart attack if we had continued on that project, so what a relief :).