[Greenbuilding] Straw Bale Flash Demo

[Bruce Donelson]

   could you support your $100 per month figure.

   my  numbers  indicate more like $100/year energy savings for the extra
   insulation of 11 inches (r50)  over 7 inches thick ( r25) walls
particularly
   if it is single story and not counting windows or any change in
infiltration
   for a north temperate climate using gas at $1.50/therm..
       ______________________________________________________________

     From:  "Zero Energy Lifestyle by Eyedestu.com" <0energy at cox.net>
     To:  "Drew A. Gillett, P.E." <deaneg at hotmail.com>
     Subject:  Re: [Greenbuilding] Straw Bale Flash Demo
     Date:  Thu, 20 Sep 2007 13:51:07 -0700
     >A 2 x 6 stud wall is about 7 inches thick when finished, and an ICF
     >wall is about 11" thick...we're only talking 4 inches difference.
     >That is 4 inches divided by 12 inches = 1/3 of a foot. Even a 3600
     >sq.ft. home is (by sq.rt.) about 60 x 60. If you make it 60.3333 x
     >60.3333 that is only 40 extr sq.ft. you probably compared a thick
     >walled house to one without walls. Instead of comparing the
     >difference.....1/3 of a foot thicker. And it will realize an energy
     >savings of over a hundred dollars a month, or over a thousand
     >dollars a year. $200 x 40 is only $800 more cost compared to well
     >over a thousand in savings. Wood houses hemorage energy.
     >

When Out On Bale made strawbale walls at the Lawrence Livermore National Lab
to test their heat loss characteristics, the best wall section had an actual
R-value of about R-25. This is a far cry from the R-50 that is still
floating around.

Of course, an R-21 fiberglass wall on 16" centers tests out around R-18,
because of the greater heat loss through the studs.

Does anyone remember what the test R-value of the 11" ICF wall is like?

Energy savings are less determined by wall thickness than wal composition,
which includes windows and leakage etc.

Bruce Donelson
A Better Builder