Hello,

I have a residential house project starting this spring in Breckenridge, Colorado (8900 elevation). Our house has a contemporary design and would like to put commercial windows in the majority of the house. Local building codes have adopted the 2006 energy code and require .35 U value for the fenestration opening. I have several questions regarding this issue.

1. I have been discouraged by some building professionals to put in commercial windows due to the lack of performance. If the window can perform at .35 or less U value what is the overwhelming difference of commercial windows having both flashed and installed properly?

2. Manufactures such as Fleetwood have achieved these U-values with high performance glass, super spacers and thermal breaks. Other than the conduction of cold through aluminum cladding it seems as if the durability would be better than wood without the maintenance.

3. I understand argon and other gasses lower the U-value as well. If it is installed in Denver 5280 elevation) through transport over 11,000 foot pass would it still be effective at our elevation 8900?

4. Overall, it seems as if the commercial windows perform as well as residential windows. Glass is the same but how does the frame affect overall performance? Thanks, Bret in Colorado