Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision
Previous revision
Next revisionBoth sides next revision
apps:biomet_pet [2017/11/10 09:25] – external edit 127.0.0.1apps:biomet_pet [2019/01/12 21:15] enviadmin
Line 12: Line 12:
  
  
-Despite its popularity, PET lacks a proper and comprehensive documentation. Basically, one needs to read the 2 papers Gagge et al. (1971) and Höppe (1984) -in german- plus the computer source code provided by VDI 3787. \\ +Despite its popularity, PET long time lacked a proper and comprehensive documentation. Basically, one needed to read the 2 papers Gagge et al. (1971) and Höppe (1984) -in german- plus the computer source code provided by VDI 3787. \\
-It has to be noted, that there are some unlogical assumptions and errors in the original set of equations. In the ENVI-met implementation, these errors have been corrected. As a consequence, PET values calculated by ENVI-met may differ from values calculated by other programs, but we see no sense in copying wrong code or unlogical assumptions. Fundamental changes from the original are marked in the description. +
  
--The description still needs to be compiled and written, please hold on-+In 2018, this gap has been closed by the paper "//The P.E.T. comfort index: Questioning the model//" by E. Walther and Q. Goestchel ([[https://www.sciencedirect.com/science/article/pii/S0360132318301896?via%3Dihub|Link to Paper]] who take the effort to summarize all the equations and assumptions. 
  
-Main changes to original PET in short :+It has to be noted, that there are some non-logical assumptions and errors in the original set of equations plus coding errors in the code published in VDI 3787. In addition, there have been better parametrisations for the Mean Radiant Temperature (TMRT) which is is not directly a part of PET but widely influences the results. 
 + 
 +In the ENVI-met implementation in BioMet 1.x, many of these errors have been corrected. As a consequence, PET values calculated by ENVI-met may differ from values calculated by other programs, but we see no sense in copying wrong code or non-logical assumptions. Fundamental changes from the original are marked in the description.  
 + 
 +Main changes in ENVI-met BioMet compared to original PET in short are:
   * For the indoor setting, the turbulent exchange coefficients for heat and vapour are calculated using the indoor air velocity instead of keeping them at the outdoor value   * For the indoor setting, the turbulent exchange coefficients for heat and vapour are calculated using the indoor air velocity instead of keeping them at the outdoor value
   * The sweat rate and the amount of sweat on the skin is set to zero when starting calculating the indoor environment   * The sweat rate and the amount of sweat on the skin is set to zero when starting calculating the indoor environment
 +
 +
 +The suggestions form Walther and Goestchel (2018)  plus several other improvements will be added to BioMet in upcoming versions.
 +
 +
  
 ===== General Idea ===== ===== General Idea =====
Line 34: Line 42:
  
  
-==== References ====+===== References =====
   * Gagge, A., Stolwijk, J., and Nishi, Y. (1971): An effective temperature scale based on a simple model of human physiological regulatory response. ASHRAE Trans., 77(1):247–262.   * Gagge, A., Stolwijk, J., and Nishi, Y. (1971): An effective temperature scale based on a simple model of human physiological regulatory response. ASHRAE Trans., 77(1):247–262.
   * Höppe, P. (1984). Die Energiebilanz des Menschen: In: Münchener Universitätsschriften- Fachbereich Physik, Wissenschaftliche Mitteilungen Nr. 49. Meteorologisches Institut, Universität München, München.   * Höppe, P. (1984). Die Energiebilanz des Menschen: In: Münchener Universitätsschriften- Fachbereich Physik, Wissenschaftliche Mitteilungen Nr. 49. Meteorologisches Institut, Universität München, München.
   * Höppe, P. (1999): The physiological equivalent temperature – a universal index for the biometeorological assessment of the thermal environment. - International Journal of Biometeorology 43, 71-75.   * Höppe, P. (1999): The physiological equivalent temperature – a universal index for the biometeorological assessment of the thermal environment. - International Journal of Biometeorology 43, 71-75.
   * VDI (2008): VDI 3787. Environmental meteorology. Methods for the human biometeorological evaluation of climate and air quality for urban and regional planning at regional level. Part I: Climate, Blatt 2/ Part 2   * VDI (2008): VDI 3787. Environmental meteorology. Methods for the human biometeorological evaluation of climate and air quality for urban and regional planning at regional level. Part I: Climate, Blatt 2/ Part 2