Signature Windows: The R5 Versus R3.33

Last week I participated in an Alliance to Save Energy webinar entitled “Window Energy Efficiency Beyond Business As Usual”. The webinar touted the benefits of super high performance R5 windows over commercially available R3.33 windows. The Department of Energy is pushing a volume purchase program to help drive the cost of R5 windows down to an acceptable premium.

I think continued evolution in window, door, and skylight performance is good for everyone and will force the better companies to increase the speed of innovation, while weeding out the lower quality/lower price players. I am not sure I agree that a DOE-sponsored volume purchase program is the best public/private partnership, but I remain open-minded.

What I am sure of is that with very few exceptions, the cost of today’s R5 windows is not at all justified by the energy saved or the carbon reduced. This remains true even if you double today’s cost of a therm (100,000 Btu)

The attached presentation puts the R5 vs. R3.33 debate in the context of Boulder City and County building codes and amplifies the “cost efficiency” of commercially available windows. While I take complete responsibility for the content of this post and the presentation, special thanks are due to David Neiger and the Populus team for helping work through the energy calculations.