LoE glass looks fairly green from the outside, so that might be pretty noticeable (unless it's a side of the house that nobody really looks at). it might be noticeable from the inside too, but it would depend on how strong the LoE coating is, and how strong the sunlight coming through is.

can you ask them for a somewhat large glass sample that you could prop up inside the clear window?

If there is a way you can use the LoE-272 coating it will not look as different right next to clear glass. I still have a couple old windows that are not coated that are next to LoE-272 coated glass windows and you cannot see the difference from the outside. I am not sure whether California requires the LoE-366 level or whether you can do the LoE-272.

well if it's hot and sunny where you live, I recommend a higher LoE and plan to eventually update the window next to it. all of us doing our part puts less strain on our ancient, failing electrical grid.

from what I understand, LoE also helps a home retain heat in the winter too!

Thanks for everyone's input, that's very helpful. To clarify a few points: Two of the windows are north facing and under trees, and we live in San Diego where we hardly use the heater (and have no AC). So the benefits of the low-E are limited for us. Also, one of the windows is basically a cosmetic upgrade from a slider to a picture window. So if it ends up looking worse then it would have been silly. For the west-facing window I am happy to embrace the low-e even if it looks different!

oh if it's north facing / shady then you're probably fine with the lowest E that's permitted in California.

if your view out of the window is lots of trees, yard, etc, I'll bet you won't notice the two different windows from the inside. the background will be so green and "busy" for you to detect a slight color difference. (just a guess.)

but like we said, it might be noticeable from the outside.

Low-E glass does offer energy efficiency. Wh would you not get it? It defeats the purpose of getting new windows.

Generally I would agree with you. But as I said above, the energy efficiency is of limited benefit for two of the windows in particular. And since one of the windows is intended as a design improvement, it will be counterproductive if it ends up looking worse. We have so many windows that swapping a few north-facing, shaded ones for low-e isn't going to affect much. What I really need to know is just how obvious the difference in tone is from inside the house, when clear and 366 windows are a few inches away from each other. It's surprisingly hard to find that out.

"when clear and 366 windows are a few inches away from each other."

As mentioned earlier, the decision is not solely limited to "clear and 366 windows". You can get energy efficiency with LoE-272 coated glass, but not have the tinting of the LoE-366 coating. Most windows manufacturers offer LoE-272 coating as their standard coating - i.e. no upcharge for it.

"What I really need to know is just how obvious the difference in tone is from inside the house"

I can only tell you the difference in tone from inside the house between clear glass and LoE-272 windows that are next to each other in my home. There is no difference in tone. Where the difference comes in is that the sun (these windows both face unobstructed SE) heats up the room and bleaches the wood furniture via the clear windows. The LoE-272 windows do not heat up the room and do not bleach the furniture.

Okay that's really helpful to know. Unfortunately I'm not sure if 272 is an option -- still waiting for the window guy to get back to me about it. He implied that SunCoatMAX is the Milgard one required by the county/state (CA). We already ruled out two other window companies so I'm trying to be diplomatic with this one... To be clear, I'm trying to decide whether to commit to the one window change at all, or just wait for some future date when we can splurge on the other at the same time so it doesn't look funny. I've seen so many discussions on houzz about problems that arise from not double checking all expectations ahead of time and I'm trying to avoid that!

I’m in California and had Milgard windows installed a few years ago. Yes, the glass will appear green, especially next to clear windows. Also, will cast greenish inside which is most noticeable when one pane is open. Is there another option to achieve the mandated efficiency?