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apps:biomet_pet [2014/08/25 17:24] – enviadmin | apps:biomet_pet [2022/07/31 18:22] – [PET and PET* (PET Reviewed)] enviadmin | ||
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- | ====== PET ====== | + | ====== PET and PET* (PET Reviewed) |
The Physiologal Equivalent Temperature (PET) is a thermal comfort index that is based on a prognostic model of the human energy balance that computes the skin temperature, | The Physiologal Equivalent Temperature (PET) is a thermal comfort index that is based on a prognostic model of the human energy balance that computes the skin temperature, | ||
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- | 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 |
- | It has to be noted, that there are some unlogical assumptions and errors in the original set of equations. In the ENVI-met implementation, | + | |
- | Main changes to original PET: | + | **In 2018, this gap has been closed by the paper "//The P.E.T. comfort index: Questioning the model//" |
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+ | In this paper as well as in ENVI-met paper it was 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. | ||
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+ | In the ENVI-met implementation of BIO-met, many of these errors have been corrected. As a consequence, | ||
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+ | Main changes | ||
* 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 resetted | + | * The sweat rate and the amount of sweat on the skin is set to zero when starting |
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+ | not adressed so far the issues: | ||
+ | * For the indoor setting, the metabolic rate shouldbe set to 80 W regardsless of the outdoor activity set. This also impacts the breathing settings | ||
+ | * For the indoor setting, the clothing level should/ | ||
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+ | == PET* (PET Reviewed) == | ||
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+ | The suggestions from Walther and Goestchel (2018) | ||
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+ | ===== General Idea ===== | ||
+ | The general idea behind PET (and other outdoor thermal comfort indices) is that we can express the thermal comfort of a human body using the skin and core temperature as reference indicators. | ||
+ | So, the basic idea behind PET for an outdoor setting is | ||
+ | - Define all incoming and outgoing fluxes at the human body | ||
+ | - Calculate a skin and a core temperature, | ||
+ | - Transpone the person into an indoor environment | ||
+ | - Reset all data that are not available in an indoor environment (direct solar radiation, forced wind movement) | ||
+ | - Search for an indoor air temperature (as only parameter) that results in the same skin temperature and core temperature as the outdoor setting. | ||
+ | - This theoretically calculated indoor temperature is called PET. | ||
- | ==== References ==== | + | ===== References ===== |
+ | * **Walther, E and Goestchel, Q. (2018): The P.E.T. comfort index: Questioning the model, Building and Environment, | ||
* 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): | * 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): | ||
* 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 |