Gorell has one of the best reputations for CS in the industry. What model Gorell were you looking at?

Gorell - new construction -Starview - triple pane with internal grids. Not sure of Gas composition.

I have heard that Gorell was high in CS. Saw that Paradigm was used in a number of Fine Homebuilding homes.House to be built in windy location (on a hill in NE PA)

Windows are to be used in superinsulated house (R-40 walls). Would you recommend these two suppliers for patio/French doors? Preference one over another?

Thanks for the reply.

Gorell has also won numerous Energy Star awards. Regardless of your choice bear in mind that the window will be the weak point in a super insulated wall. A.20U equates to an R5 hole in an R40 wall. This is a big step. You will notice a difference when standing near the window. The installation also becomes very important so be sure choose a qualified installer. The area between the window frame and the adjoining wall must be properly flashed, sealed and insulated. Best of Luck