I am in the Chicago area and chose LoE 272. I read on this forum that LoE 366 glass should only be used in a "cooling dominated climate" such as Texas, Florida, Arizona. As we are only cooling here for 3-4 months out of 12, I opted for LoE 272.

Some people use both 272 and 366 in their homes for different windows that face different directions; i.e. 366 for south-facing windows and 272 for north-facing or shaded windows. I am happy though with my all LoE 272 windows, even the ones that face south and have no shade.

Thank you SO MUCH for responding! Can I ask- is the glass noticeably darker than a clear, un-coated glass? Do you still get a lot of light into your home with the 272? I'm actually more nervous about blocking too much light, versus the energy efficiency angle.

My LoE 272 windows replaced Pellas that had no UV coating (as an aside, don't get Pellas, avoid). I have not replaced all my windows (too expensive), but am replacing them a few at a time. So I can compare them since I currently have both. I have several very large windows that let in a lot of light, and there is no problem with that. I do not see that the glass is darker. I definitely notice less burning and sun bleaching my furniture and no longer overheating my south-facing rooms.

I will say that my house plants that need a lot of sun have not flowered or grown, even though I was assured the LoE 272 would not affect them. My plants that need less sun like my African Violets are doing well.

You should really speak with your contractor too since it sounds like he has proposed LoE 366. My contractor told me our climate doesn't need that though he would have ordered them if I asked.

So helpful- thank you! And that is particularly useful that you can see the new LoE 272 compared to your old windows with no coating, and you don't notice a difference in the glass darkness/tint. I so appreciate it!!!

Thank you so much!!!

LowE coatings were originally developed to provide triple pane performance in dual pane windows; so by way of comparison imagine if you had three lites of glass in the window or two lites with LoE-272 on the outer lite.

And as an aside, these are glass-only numbers so they won't match the finished window performance values.

Triple pane - U-value .29, SHGC .70, visible light transmittance 75% (of available light)

Dual pane with 272 on surface 2 - U .25, SHGC .41, VLT 72%.

So if you can imagine looking thru three pieces of glass, that isn't far off of the look of a dual pane with LoE-272.