<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Dear Stovers,<div class="">If I understand this graph it is fascinating. </div><div class="">It takes less energy to maintain a temperature at 40c than it does to maintain a temperature of 15C or 75C. </div><div class=""><br class=""></div><div class="">Our body temperature requires the least amount of energy to be maintained at 37c</div><div class=""><br class=""></div><div class="">Compost sent to curing piles cools and hovers around 40c with composers thinking it is still very active but it takes less microbial activity to maintain 40c than if it were to maintain at 25c.</div><div class=""><br class=""></div><div class="">Anaerobic digesters natural go to 36C where it requires the least microbial activity to maintain that temperature.</div><div class=""><br class=""></div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Whatever it is about water molecule that lowers the input of energy required to maintain a temperature of 40c seems well used by our natural environment. </div><div class=""><br class=""></div><div class=""><br class=""></div><div class="">Regards</div><div class=""><br class=""></div><div class="">Frank (sitting under the Bodhi Tree)</div><div class=""><br class=""></div><div class=""><p class="MsoPlainText" style="margin: 0cm 0cm 0.0001pt; font-size: 10.5pt; font-family: Consolas;">The thermal capacity of water is not a constant. At 1 atmosphere pressure a good correlation is <o:p class=""></o:p></p><p class="MsoPlainText" style="margin: 0cm 0cm 0.0001pt; font-size: 10.5pt; font-family: Consolas;"><img class="Apple-web-attachment-container" src="cid:image002.jpg@01D0FB5A.E9128D80" alt="C_p(T)={4.214-2.286\times10^{-3}T+4.991\times10^{-5}T^2-4.519\times10^{-7}T^3+1.857\times10^{-9}T^4}" id="Picture_x0020_1"><o:p class=""></o:p></p><p class="MsoPlainText" style="margin: 0cm 0cm 0.0001pt; font-size: 10.5pt; font-family: Consolas;"><a href="https://syeilendrapramuditya.wordpress.com/2011/08/20/water-thermodynamic-properties/" style="color: purple;" class="">https://syeilendrapramuditya.wordpress.com/2011/08/20/water-thermodynamic-properties/</a><o:p class=""></o:p></p><p class="MsoPlainText" style="margin: 0cm 0cm 0.0001pt; font-size: 10.5pt; font-family: Consolas;">which, of course, you have to integrate over the delta T to get the effective value. <o:p class=""></o:p></p><p class="MsoPlainText" style="margin: 0cm 0cm 0.0001pt; font-size: 10.5pt; font-family: Consolas;"><img class="Apple-web-attachment-container" src="cid:image001.gif@01D0FB5B.1DFD7550" alt="https://syeilendrapramuditya.files.wordpress.com/2011/08/water_specific_heat_capacity_vs_temperature.gif?w=540&h=330" border="0" id="Picture_x0020_2"><o:p class=""></o:p></p><p class="MsoPlainText" style="margin: 0cm 0cm 0.0001pt; font-size: 10.5pt; font-family: Consolas;">The thermal capacity is less sensitive to pressure over the range you are concerned about – the change to 1500m altitude will affect the 3rd decimal place in value calculated at constant pressure.<o:p class=""></o:p></p><p class="MsoPlainText" style="margin: 0cm 0cm 0.0001pt; font-size: 10.5pt; font-family: Consolas;"><o:p class=""> </o:p></p></div></body></html>