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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Dear Paul A<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>“</span>[Technical note: Stove testing should measure separately the emissions during each of the different combustion modes instead of just reporting averages that include emissions from two or more combustion modes. I think we can do some of that at this summer's Stove Camps at CREEC - Uganda and at Aprovecho - Oregon-USA where emissions equipment is available.]” <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Just on this point, it is fine to call for testing and reporting of different attributes however I would ask that people consider the difference between development of a product and the ‘testing’ for comparative purposes. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>The reason the HTP method was developed was to rapidly assess what the conditions were in a stove that produced the lowest emissions and best performance. At that it has been very successfully applied, most recently in Indonesia where the improvement of the ubiquitous Keren Stove has seen a remarkable turn of fortunes in the lab. <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>The HPT is not more much than a method of recording performance continuously. It is ideal for the purpose described above. If one wants a performance number for any period of time it is only necessary to sum the emissions from time A to time B, or from the beginning to the end of a task. One of the recent developments has been the application of not an arbitrary selection of times for the beginning and ending, but to examine where moving the beginning and end makes any difference to the performance number. If it does, the metric is probably not ‘characteristic’. An example is the determination of the heat transfer efficiency at any power level. If the chosen start and finish times change the assessment, then it is probably not a representative figure because the heat transfer efficiency is a characteristic of the product, not something that varies.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>The YDD lab has produced some tests this year demonstrating what a robust assessment of heat transfer efficiency looks like. Moving the beginning or ending time by 10 minutes makes no difference to the assessment (no meaningful difference). Several people have called for other tests that provide pretty much the same result though they were not based on an HTP. Piet Visser comes to mind. He likes a long, high power boiling pot heat transfer number. I call this the hot stove high power heat transfer efficiency. The same can be done for other power levels provided the pot has cold, not boiling water in it.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Regards<br>Crispin<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p></div></body></html>