If they weren't such a weak point in the insulation and in the way of my dream of running "silent" ie. no generator *almost* all the time, I would keep them just they way they are. They are beautiful and horribly inefficient. They need to be updated to 2015 energy standards.
Anyways, I need the Bees Knees when it comes to efficiency and in a similar dimension 27x30, as thin as possible. I can work the rest in terms of installing it, just would prefer to be around the 2" Frame depth, insulated, and double hung and with a good e-coating (low SHGC) .. having a hard time finding good options for a reasonable price. The custom RV window guys want like $300+...which i dont like.
Anyone found any good options that keep the "look" of the aluminum frame, double hung, but with all of the above
I plan on putting up to 1300 Watts of solar and a 18kWhr battery bank. Mini-split DC A/C.... you know what im thinking