That was quite the read, had to do it several times to get the gist. Very thorough.

IMO triples are a must, good call on that one.

Don't mix coatings on the same wall, even at different elevations. It looks odd and you won't like the results. One exception to that might be if the lower windows are under a canopy and are in shadow most of the day, except in late evening as the sun sets.

Even in winter it's possible to overheat a room facing west if it has big bright sunny windows with lots of direct solar exposure. Using a high solar gain coating like 180 alone on those windows might make it uncomfortable on bright winter days but will make it unbearable in summer if there is no way to block the sun from shining directly on them.

Use 366 for any unprotected big west facing windows, like the ones in your bedroom and living/dining areas and add the 180 option to surface 5 for the best winter energy performance.

Yes 366 has a slight greenish hue, and yes, the room will be darker when compared with clear glass, or no glass, but when in full sun you won't notice that at all. You also won't notice that you don't have to leave the room because it's unbearably hot. There are hundreds of millions of windows in Canada and US that have 366 or equivalent "green" windows, and the people either don't notice or don't care because they are happy with the results. Sunlight shining through trees will give you more green in the house than the windows will.

Probably the same advice for any south facing windows that don't have overhangs or trees to protect them from the summer sun. If there is protection from summer sun then I would opt for 180 on surface 2 and surface 5....One caveat for 180/180 facing south.

Any LowE coating will lower solar heat gain when used on surface 2 versus surface 3 (or 5 in a triple). Summer sun is high in the sky in summer so solar rays will hit south facing glass at an oblique angle, even if there is no overhang protecting the window. With any coating on surface 2, much of the sun’s energy will be reflected rather than absorbed or transmitted by the combination of coating and angle. Given the right set of conditions, using 180 on surface 2 and 5 might be an option. Also in spring and fall, when a little extra solar heat might be welcome, coincidently the sun happens to be lower in the southern sky so less reflection and more transmission. How much is too much again depends on your specific environmental conditions.

Quick and dirty illustration:

Also yes, the Guardian triple silver is greener than the Cardinal, but you likely won't notice unless you really think about it. There's more potential for a noticeable difference between windows with the same coating when one is in shade and one is in sun.

I like the idea of bright sun in the morning, especially in winter, so would look at 180/180 for east and north windows.

I appreciate the mention with the smart dude above me here. When it comes to glazing packages and the science in them...you're dealing with the man right here.

Thanks for the response from you both!

Oberon, thanks for the detailed response, glad to hear you're on board with the triple everywhere. I've included pictures of the labeled elevations to give a better understanding of our unique situation.

Regarding coating selections I unfortunately won't have the ability to specify which coating goes on what surface. I'll have to pick from the following options:

Option 1: 180/clear/clear (R5.3)

Option 2: 366/clear/clear (R5.6)

Option 3: clear/180/180/ (R7.7) - I'm wondering if this is a typo and it's actually 180/180/clear?

Option 4: 180/180/i89 (R8.5)

Option 5: 270/270/i89 (9.1)

So currently I have all east windows + the 2 stacked south windows connected to the south/east corner rooms in clear/180/180. I thought the two south windows here made sense since it will keep these rooms consistent with light. The roof line has a 2ft overhang so the upstairs would get some shielding seasonally as per your helpful diagram. The 1st floor below would get no cover. But I figure we can just lower the blinds here for the summer to avoid unwanted heat gain since they are relatively small windows.

Then everything else (west and north) is set to 366/clear/clear. I was thinking since there are only two 2ft wide windows to living spaces on the north sides, we'd just keep those 366 to work with the nearby large 366 windows on the west walls. The lower super wide shallow windows facing north and west on the 1st floor are for the garage, so I'm less concerned there about more light coming in.

Where it gets extra tricky as you can see from the south elevation, is that both the kitchen window and sliding door are under the 12ft porch overhang. Currently I have the kitchen window set to 366 and was going to have the sliding door upgraded to be Guardian 62/27 (from standard 80/71). I would do this to make everything match as best as possible with the dominant and large west facing windows in 366. But, since it's going to be under that overhang and very dark, with the sliding doors a slightly different tint than 366 regardless, I'm wondering if it makes sense to switch the kitchen window to 180 and keep the patio door the standard Guardian 80/71 (the 180 equivalent)? This would lighten everything up under the porch and have a closer match between the kitchen sink window and sliding door under the porch, but it would be brighter than the nearby west 366 windows and narrow 366 north window across the way. In fact the VT of the sliding door being double glaze would be around a 20% difference than the nearby triple 366 west facing windows.

Also note, for the upstairs family room area that is facing west above, that one south window above the porch roof is currently at 366 as is the north door window (to the upper deck) which is across the way. Was thinking this would be smart to keep the entire room here consistent with the large west windows in 366.

Who is the window company?

The R value numbers you listed are center of glass and not window performance

Per coating location -

Option 1 the coating should be on surface 3

Option 2 should be surface 2

Option 3 should be on surfaces 2 and 5

Option 4 and 5 coating surface 2, 4, and 6

So they have 270 but only in the configuration listed?

What a gem to have someone like this.

There is no one close to Obi1

It's a smaller private window company named Del. Got quotes for Marvin and they were over double the price and that was only for double glaze versus triple, so well out of our budget.

That's correct, they only have 270 in the configuration listed for triple pane unfortunately.

Thanks for the listed surface locations of the coatings. It seems like option 1 and 3 would not be possible scenarios with Del based on their breakdowns of which panes have the coatings. From your list of surface breakdowns, are these the only coating locations that Cardinal will supply to all window manufactures, or do they switch up the locations based on window manufactures specific requests? For example, based on option 3 being listed as clear/180/180, is it possible that they provide the glass for Del with 180 on surface 3 or 4 + 5? And if so, would that be an issue in how it preforms?

Besides the brochure spec only showing the R values for all packages, since whole window U factors are shown on the quote, I can see them for option 2 and 3 only:

Option 2 (366/clear/clear) is between .20-.21

Option 3 (clear/180/180) is between .16-.18

One other question I have is regarding the difference in tint/hue from Cardinal 366 and Guardian 62/27. Does anyone have experience seeing the two glasses next to each other? Trying to get an idea of how noticeably different they would look.

Thanks.

Coating decision day today. I'm thinking the options at play (unless other suggestions should be considered) are:

Glass package option #3 (clear/180/180): East windows + 2 stacked south windows at south/east corner.

Glass package option #2 (366/clear/clear): All other windows with sliding door Guardian 62/27 to try and match.

Glass package option #3 (clear/180/180): East windows + 2 stacked south windows at south/east corner + south kitchen window under covered porch with sliding door next to it as Guardian 80/71.

Glass package option #2 (366/clear/clear): All other windows

Glass package option #2 (366/clear/clear): Everything + Guardian 62/27 to match (currently quoted)

My comments on the different glass packages and where the coating should go was based on how they are normally distributed in the IGU.

For example 180 is designed as a surface 3 coating. It can go on surface 2 and since it is such a neutral color you really won't see a difference, but while U factor doesn't care what surface has the coating, placing the coating on surface 2 does cut down on solar heat gain which can be a plus or a minus depending on what you are looking for.

All of the coatings that you are looking at are applied in a sputter down process, meaning that the the coating are applied to the top side of the glass on the coating line. What that means is that hypothetically while a glass lite that has already been coated can be taken back to the beginning of the line and flipped over so that it can be coated on both sides, don't count on it happening. What that means is that coatings are only on one side of the glass, so in a dual pane IGU you can have a coating on surface 2 or surface 3, and if on surface 2 you can also have a surface 4 coating, but if on surface 3 then you won't...this applies whether dealing with 180, 270, or 366. Same applies to triple pane, but with more options, as listed in my previous post.

In a dual pane technically you can have a coating on surface 2 and surface 3 at the same time, and I have heard of window companies who claim to do it, but only if you have no particular desire to have that window for any length of time, because it is a very not good idea.

As I said earlier, use 366 on west facing windows, with 180 on surface 5 if offered.

On north and east I would use 180 surface 2 and 5, or possibly it could be 3 and 5, or less likely IMO, 2 and 4, and that could explain what you received from the window company. If that's the case then I would expect that the middle lite might be tempered, but since the IG's are made by Cardinal they would tell the window company exactly what is a good idea and what is a bad idea. All are technically possible, but location would have an effect on performance values.

On the south side I would look at 180 on 2 and 5. In that location I would prefer not to have the coating on surface 3 unless you had some good overhangs to protect the glass in summer.

Per the Guardian, pick the one that matches the windows and don't sweat the slight differences. Unless you or someone else is very color sensitive, it isn't that big of a difference unless they are side by side in an open area. On the windows under the overhang I would prefer 180 on one lite for maximum light into the room.

Thanks Oberon, very informative. Unfortunately I'm limited to the options they provide and even some of those aren't clear in terms of what specific surface they're applied to. So I'm going to have to order and hope for the best. I think the biggest challenge is that most of these windows will be almost next to each other and in one big open space, so noticing the difference will likely be as noticeable as it could get. I guess that is the major pro to doing everything in 366/clear/clear.

With any 180 configuration I'd prefer as low a SHGC a possible since I don't need the heat gain. Without knowing the true configuration of option 3 (clear/180/180), and it maybe being on surface 3 and 5, would that increase the SHGC vs. having a single 180 on surface 2 only? I understand that putting it on surface 3 increases the SHGC, but does adding it to another surface (say 5), reduce it back down or further increase it? Trying to understand what I can expect in regards to SHGC with the single surface 2 180 vs. a hypothetical surface 3 and 5 application.

If you are worried more about cooling than heating then I would consider the 366 option for all windows and order the doors with Guardian 62/27 to match. It would certainly simplify the decision.

My thought was that you were trying more for winter performance, but even in winter the 366 option will give you excellent U factor performance and it will help to keep your home cooler in summer substantially more than using 180.

Adding another 180 coating to surface 5 of the 180 triple does lower the SHGC of the IGU, but even adding a third lite as in dual to triple will do that, just not as much as adding a coated lite will do.

Thanks this is super helpful. As you pointed out with the U factor even with 366 in triple pane still being really good, I think the main appeal to consider any 180 at this point would be for the more visible light that would get into the house (the extra U factor increase with 2 180 coatings being extra incentive). Looking at the cardinal charts 180 would add 11-14% more light over the 366 (366 triple being 59% VT, 180 on 1 surface being 73% and 180 on 2 surface being 70%. But perhaps it's not worth that extra effort of doing so. I know why wife was also somewhat concerned about all the plants she intends on having in the house, but I'm really wondering if an 11-14% difference will have much effect.