We are getting estimates for construction of a new home. The contractors are listing Pella Proline GBG (Grill between glass) double hung windows, but I am having trouble determining if this is the right product for us. When asked, we were told these are aluminum clad windows, but I don't know anything about R-value, U-value, and I can't tell from the Pella web site.

We live in Chicago and want a lot of natural light in our new home so using appropriate windows is very important. My initial thoughts are vinyl clad may be better to reduce transmission of cold into the house in the winter, but my head is spinning from trying to figure this out.

Any wisdom from Houzzers would be greatly appreciated!