[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

RE: GSBN:CalifoRnian values (was re: from the Crest list)

The difference between R-30 and
R-45 means the difference between 0.033 Btu/hr/SF/F and 0.022
Btu/hr/SF/F. Repeat after me, "It just doesn't matter!  It just
doesn't matter."  I suggest we move on to other, more meaningful


In terms of a functioning house, I agree with Nehemiah that the exact R-value for SB doesn't matter. I also like the statement that I first heard from Danny Buck of Living Structures: The R-value of a strawbale wall is "enough."

When it comes to educating the public about strawbale building, I feel a need to say more. What I say these days is something like, "A straw bale has a R-value of 45 or 50. A well-built wall can have an R-value of 30 for the entire wall, according to tests done at Oak Ridge National Laboratories. Fiberglass batts for 2 x 6 framing are rated at R-19 for the material, so that's less than half of the value for a straw bale. Oak Ridge tested frame walls insulated with fiberglass batts, and measured R-values from a little over R-7 to R-12. As with the raw materials, a fiberglass-insulated frame wall will yield less than half the insulative value of a strawbale wall."

I haven't figured out a way to say it more concisely, and still convey the needed information. Plenty of people have come up to me and said, "I hear that strawbales are only R-30. Since fiberglass is R-19, why should I bother with bales?" I think it takes a bit of explanation to clarify the fallacies in that kind of statement.


Derek Roff
Language Learning Center, MSC03-2100
Ortega Hall Rm 129, 1 University of New Mexico
Albuquerque, NM 87131-0001
505/277-7368, fax 505/277-3885
Internet: derek@...