[Stoves] Thermal performance of materials gets a Heterogeneous makeover

Crispin Pemberton-Pigott crispinpigott at gmail.com
Mon Aug 29 05:17:07 CDT 2011


Dear Friends

 

There is a brief discussion of the R-value used to report building
insulation metrics at
http://www.greenbuildingadvisor.com/blogs/dept/musings/bold-attempt-slay-r-v
alue?lookup=auto
<http://www.greenbuildingadvisor.com/blogs/dept/musings/bold-attempt-slay-r-
value?lookup=auto&V27=&V28=&V29=&V30=&V31=&V32=&V33=&V34=&V35=&V55=&V56=&Tau
n_Per_Flag=true&utm_source=email&utm_medium=eletter&utm_content=20110829-r-v
alue-obsolete&utm_campaign=fine-homebuilding>
&V27=&V28=&V29=&V30=&V31=&V32=&V33=&V34=&V35=&V55=&V56=&Taun_Per_Flag=true&u
tm_source=email&utm_medium=eletter&utm_content=20110829-r-value-obsolete&utm
_campaign=fine-homebuilding

 

The main point is that the insulation value of materials changes with
temperature and how it is applied. 

 

One proposal is that a heterogeneous test report (a set of charted curves
reflecting performance under different conditions) be used instead of a
single R-value. (R is the inverse of the U value, or thermal conductance).

 

"R-value took us a long way down the path," Lstiburek said. "Fifty years is
a long time."

 

In the same vein, I advocate the use of stove performance tests and
performance reporting reflecting how the stove works under different
conditions, primarily different pot sizes, different power levels and
different fuel moisture levels.

 

Presented with a chart of performance curves for different stoves, the buyer
can select the one that performs best by matching the offerings to their
fuel type(s) and cooking or heating needs. Fortunately it is much easier to
test stoves heterogeneously than a building (read the article!).

 

Regards

Crispin

 

 

 

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