[Stoves] WBT disagrements

Mon Jan 15 18:52:29 CST 2018

Dear Tom,

I’d be very happy to present the case against the WBT at ETHOS.

But as you know, I live in France, and I was not planning to go to the U.S. As I said to Elisa, I am more than willing to come, if ETHOS is able to pay for the trip.

I have other things to do in France at the end of January. So I am not sure I want to travel on my own budget to the U.S. only to say what I have been already saying for, not 18 months, but more like 12 months. It’s been much more for Crispin, Philip, and others. 

I am already spending my own time, for free, on this initiative. I haven’t resolved myself to start spending my own money on it, just to repeat what has been said so many times.

Tom, you say « WBT sponsors ». Do you mean WBT supporters?

If it is supporters, I asked many times on this list and ask again: who are they?

As Philip says, no one has been willing to discuss the WBT issues for years, on, or off-list.

If we want the largest number of people to benefit from constructive discussion, the Bioenergylist is the best place for that.

Why should I have to take the plane, travel a total of 16 000 km to go and meet in person the WBT supporters, at their home, to repeat to them exactly the same things I have been repeating for months, things that they have known for years? When they haven’t even read the studies about the WBT, nor the alternative protocols?

This was another thing I was trying to convey to Elisa. Testing related issues don’t have to be discussed at ETHOS, nor in the TC 285 for that matter, to start to exist in the realm of stoves. There are important efforts being done, that are not necessarily being talked about at ETHOS. There are people working on stoves, who are not going at ETHOS.

ETHOS shouldn’t be the institution that validates and officialize what is important, and what is not.

Important matters shouldn’t have to wait to be presented at ETHOS, to be carefully studied by the parties involved in stove testing.

« WBT sponsors likely won’t answer questions unless pressed to do so with a clear demonstration of need. »

Then maybe I should copy again the summary of what are the WBT issues:

« Some of WBT critical issues remain unsolved. In particular, the main weakness of the WBT concerns its real-life relevance. […] Criticism about WBT concerns also the repeatability of the protocol, with a number of researchers claiming that it would need to be reviewed in terms of accuracy. […] As a matter of fact, uncertainties related to temperature reading and vaporisation in the boiling region lead to high variability between test replicates.

A lot of debate has been made around formulation of metrics, primarily on thermal efficiency, which is often interpreted as the most immediate and distinctive stove performance parameter. Studies from Bailis et al. highlighted how relying on WBT thermal efficiency outputs, regardless of the relative importance of high and low power cooking tasks among the target population, can lead to misleading interpretations. Furthermore, Zhang et al. and Jetter et al. questioned the scientific meaningfulness of thermal efficiency at simmering. 

Finally, some unsolved issues concerning statistical significance of data are worth mentioning. WBT 4.2.3 includes “Statistic Lessons for Performance Testing”. The appendix specifies that the minimum number of test replicates for each model of stove should be three, […] Wang et al. investigated this topic using a simplified version of the WBT 3.0 and demonstrated that more than 5 replicates are likely to be required to avoid impractically large 95% confidence intervals and that even more replicates may be required to demonstrate a statistically significant difference in performance between two or more stoves. »

What in this demonstration of need is not clear?

There might be an option. I put Elisa in copy. That would be great if I could do a short presentation at ETHOS, by video conference, about the WBT issues, from Paris. Then it can be followed by a discussion.

That would be a great way to have this discussion.

Tom, Elisa, what do you think?

Best,

Xavier

De : Stoves [mailto:stoves-bounces at lists.bioenergylists.org] De la part de Tom Miles
Envoyé : samedi 13 janvier 2018 04:50
À : 'Discussion of biomass cooking stoves'
Objet : Re: [Stoves] WBT disagrements

If challenging the WBT is so important why not discuss it with your peers? The purpose of ETHOS is to have a conversation about these issues. After 18 months of criticism of the WBT on this list I expected to see a presentation with a scientific comparison of stove test methods. I don’t see one on the agenda. Are none of the WBT critics going to ETHOS?  

http://www.ethoscon.com/ethos-2018-agenda/

Tom

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