[Greenbuilding] [BULK] FW: How green is cellulose infill? / thermal bridging?

[Lawrence Lile]

When I did some modeling of thermal bridging in a standard 2X6 wall, I
came to the conclusion that a thick layer of foam insulation (1" or more
- I've used as much as 1.5") is a good practical way to limit the
effects of thermal bridging.  The second way is to use Advanced Framing
techniques, which reduce the stacks of framing members at places like
corners or intersecting walls.  

I wasn't able to get all of the advanced framing techniques past my
building inspector, but we were able to use some of them.  Here is a
link to more info:  

http://www.energystar.gov/ia/home_improvement/home_solutions/doeframing.
pdf
 

--Lawrence Lile


-----Original Message-----
From: greenbuilding-bounces at listserv.repp.org
[mailto:greenbuilding-bounces at listserv.repp.org] On Behalf Of Alan
Abrams
Sent: Monday, July 10, 2006 3:25 PM
To: greenbuilding at listserv.repp.org
Subject: [BULK] [Greenbuilding] FW: How green is cellulose infill? /
thermal bridging?
Importance: Low


 And two, to minimize
thermal bridging. If the deeper wall were constructed simply of deeper
studs (2x8, or 2x10 for example) you might have an R-24 or even R-35
wall (cellulose is between R-3 and R-3.5, in my book), but it would have
all these "stripes" where the studs are that would be more like R-8 or
R-10. 

Hmmmm, anyone have any hard data on this issue of thermal bridging?  My
guess is that what is observed (in infrared photography, etc) is to a
large extent convection along the edge of fiberglass batts.  How much
heat does a
2x6 actually conduct, particularly if it's snugly insulated, say, with
cellulose or sprayed in place polyurethane?  What is the moisture
content of wood members, when tested for thermal performance, compared
to a stud that lives in a thoroughly dried out wall cavity?  Is wood
getting a bad rap, thermally speaking?

Alan Abrams
Washington, DC


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