<HTML><BODY>Dear Francesco I don't have direct experience with PCM on an external roof felt, however have done some calculations in regard to adding external thermal mass to a facade panel (in the form of a heavy plaster board). In general, depending on the insulation between thermal mass and the interior, the effect was small to insignificant (the better the insulation, of course, the smaller the effect). I would assume that you will find something similar with the PCM. If you are using the original data for the (original) ESP-r PCM, then I think it is a "low temperature" type (i.e. designed for indoor air temperatures). If used on a roof with direct solar radiation, it will most likely quickly melt and then behave as "any old material" in terms of heat capacity. Also, "roof felt" sounds like very little PCM mass. All said, I would expect only a small effect on internal temperatures (whatever "small" means, here  ;o) ). Best Achim --------- Original-Nachricht -------- Von: francesco.frontini@polimi.it An: "esp-r@lists.strath.ac.uk" <esp-r@lists.strath.ac.uk> Betreff: [esp-r] Effect of PCM in roof construction Datum: 13/12/10 20:48 Dear all, do you have any experience of PCM on external roof felt? A colleague would like to simulate the effect of PCM if they are integrated in flat roof construction. We try to use the model implemented in ESP-r and seems to work properly (we have some doubt on the input parameters) but he realized that the PCM has a really small influence on the inside surface temperature. Any experience or suggestion? Best regard Francesco ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program. _______________________________________________ esp-r mailing list <a href="mailto:esp-r@lists.strath.ac.uk" class="autolink">esp-r@lists.strath.ac.uk</a> <a href="http://lists.strath.ac.uk/mailman/listinfo/esp-r" target="_blank" class="autolink">http://lists.strath.ac.uk/mailman/listinfo/esp-r</a> </BODY></HTML>