[Stoves] Stove testing with and beyond the WBT

Sat Apr 6 22:45:49 CDT 2013

Dear Paul

I think you put that very well.

>As far as I know (and I do NOT specialize in this), very few sets of RAW
data are available for examination.   

I think this is correct. We have the spreadsheets - I have many different
copies of the UCB/ETHOS WBT going back to 2003. By entering in the output
data it is sometimes possible to work out what the numbers were in some
cells and therefore make an updated calculation but not always. At a bare
minimum we need a screenshot of the Test1-Test3 pages. It is then a matter
of manually reproducing the entries.

The problem with this approach is that the different versions of WBT 3.0 3.1
and 4.1.2 cannot be differentiated by looking at the Test pages. So it is
not known which corrections have already been applied. It is much better to
have the spreadsheet if one of those was used.

As wood stove results have a high variability it is not possible to use one
or two and get a meaningful guide about where it should be on a performance
inventory chart.

There are, or course, other tests in common use outside the USA. They either
treat the raw data differently or they record different things and are not
directly compatible or convertible. 

Were the calculated performance metrics between versions of tests not so
different, based on the math alone, I would be tempted to say use the old
ones as a general guide and start with the newest ideas and retain enough
information to be able to update them. The situation is however not so
favourable as the information provided is most frequently expected to tell
the policy maker how much fuel a stove consumes from the environment. That
being the case, the divergence is large, sometimes more than 250% of value.

With Aprovecho, Berkeley, Colorado State, Univ of Johannesburg, the States
of India and China and South Africa, the EU and various US states applying
different understandings to the issue, whatever is agreed (which is always
an interim solution) must be done with a clear notion of what the questions
are and how such question are answered.

>Well, having "older test results" possibly deemed NON-applicable would
really shake up the stove evaluation situation.   How old is "old"?   Are
the EPA Jetter-run tests already "old?"   

It was agreed in N Carolina this year that the current version (WBT 4.2.1)
is valid for general use until updated again. This automatically defines any
test performed using WBT 4.1.2 (pre-17 June 2012) or earlier 'old'. The same
fuel consumption numbers used as input for previous versions are
significantly (meaning more than 1 standard deviation) different, meaning
'detectably different'. That should settle the question of whether
correcting forward is needed or not.

If we are to still have a 'water boiling test only' as one complete tool, it
requires several more corrections and the removal of invalid calculated
numbers from the sheet so people stop reporting them as if they tell us
something useful. The useful numbers should of course be retained. But prior
to that we need to have a conversation about concepts - what the test is
supposed to tell us and what to do to answer those questions.

Paul, I appreciate the time you are putting into this. It is very important
that these issues be discussed so ideas are solicited.

Regards

Crispin

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