I live is place where medium cold winters but hot summers we have overhangs which do exactly what yours do and we are grateful Our house faes south teh on;y window on the west side allows too much heat and UV in during the summer so we have soalr shades on that window it totally contols the heat and UV but allows us to keep the aewsome view . We have double paned windows they seem to do the job without argon but a well made window. We also get pretty good winds too. We have only sealed un opening widows on the kitcehn and LR in our house there is a lot of open spce areas so air mopvement not a big deal I never like sliders and with wind casements are IMO not great either so double hungs are what we have in the bedrooms . All the info you give here is something I have never got bogged down with but we of course do not have a passive solar house just a well designed 1956 MCM ranch that functions really well for heating and cooling.

Thanks for your reply, Patricia. Yes, we definitely are digging into this pretty deeply, mainly because it’s an expensive project and we tend to keep things way beyond their normal life :)

I found a post on here from a couple years ago from oberon476 that has photos of clear, 270, 272, and 366 against white paper. Even if 180 was like clear glass, 366 didn’t seem too different except in reflection. So maybe we could live with the aesthetics but still wonder about what’s best for passive solar homes. In our climate, does anyone think 270 or 272 would be a good compromise of halving the SHGC we have now (clear double pane) for the less than 3 months we have hot sun coming in the west side vs almost 2/3 reduction with 366? We don’t use AC but it would be nice for 2-4 weeks of the summer to give some perspective on how short the heat issue is. It seems that the little bit of additional heat in the shoulder months that 270/272 would let in would be nice (in winter the sun sets behind trees too early to give much heat). We burn firewood for heat.

Thank you for any thoughts.