Should We Use R-Values?

John G. Swanson
April 6, 2010
THE TALK... | Codes & Standards

Last week, I asked about the impact of the DOE's R-5 window program.  One possible effect the program could have–which no one mentioned specifically, but which I have wondered about since DOE first announced it–was a possible shift away from the industry's usual use of U-factors to R-values. 

U-factors, as long as NFRC has been around, has been the standard way to rate the thermal performance of windows, doors and skylights.  R-values, a terminology used commonly when talking about walls, insulation and other building materials, however, do have some fans in the industry.  Apparently, some DOE officials are inclined to the use of R-values as well.

Now I will confess, I don't understand all the pros and cons of each term.  But that won't stop me from asking do you think using R-values is a good idea?  That's our poll question of the week.

And, of course, I'd like to hear from you. Email me and tell me why would such a change be helpful? Or if you don't think we should change, why would it be harmful?  By the way, over the years, I've heard the two numbers are reciprical, but they are not exactly reciprical.  If you'd like to earn bonus points this week, send me a simple explanation of R-value vs. U-factor.  It would be much appreciated.

Should we change to R-values to rate windows and doors?

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