I'm honesty quite surprised to see all the positive comments about Pella. I've done extensive research on windows (reading efficiency ratings and through many forums) and as a result, I was turned away from Pella.
Not only are fiberglass windows stronger, they are also more efficient than vinyl because the material is less conductive. Some high end window companies like
Fibertec fill the fiberglass window frame cavity with foam for ultimate efficiency. Their windows definitely aren't cheap though.
Dave, I would strongly suggest you spend some time on the
U.S. Energy Star website. You just plug your location information in and it will give you a detailed list of certified windows for your climate. I know for my climate Pella isn't ranked in the top for efficiency (ER rating).
It's also good to be an educated buyer, and
this very short video explains what the ratings mean, and what U factor and/or SHC you want based on the environment.
