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apps:biomet_utci [2015/04/01 00:02] – enviadmin | apps:biomet_utci [2020/07/09 14:59] – enviadmin |
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====== UTCI ====== | ====== UTCI ====== |
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The calculation of UTCI is based on a 6th order polynomial regression function estimating UTCI from wind speed, air temperature, mean radiant temperature and air vapour pressure (see [[http://www.utci.org/utci_doku.php|COST 730 Webpage]]). Due to that approach, there is almost nothing that can be changed in the personal settings such as clothing, activity etc. | The UTCI was first integrated in EnvimetV4 in 2013. The calculation of UTCI is based on a 6th order polynomial regression function estimating UTCI from wind speed, air temperature, mean radiant temperature and air vapour pressure (see [[http://www.utci.org/utci_doku.php|COST 730 Webpage]]). Due to that approach, there is almost nothing that can be changed in the personal settings such as clothing, activity etc. |
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As UTCI refers to the 10 m level, ENVI-met BioMet rescales the outputs for the **required** level (pedestrian level) using the 10 m level data using the logarithmic wind power profile | As the UTCI calculation expects the wind given at the 10 m level, ENVI-met BioMet uses the calculated local wind speed $Wind_{zlevel}$ in the model domain related to the pedestrian level ($zlevel$) and scales it up to the 10 m level equivalent using the logarithmic wind power profile |
$$v_{10m} := ln(10 / z0) / ln(zlevel / z0) * wind10m$$ | $$ Wind_{10m} = \frac{ln(10 / z0)}{ln(zlevel / z0)} \cdot Wind_{zlevel}$$ |
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Obviously, that doesn't make much sense as the $z0$ roughness value is unkown for most sites, but ENVI-met provides detailed and calculated wind flow data for all levels. | In other words, if you calculate UTCI at some point for zlevel= 1.6 m, all ENVI-met data such as air temperature or radiative temperature will be used from this level, except of the wind speed which will be extrapolated to the 10 m level value. |
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| Obviously, that doesn't make much sense as the $z0$ roughness value is unknown for most sites, but ENVI-met provides detailed and calculated wind flow data for all levels. |
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==== Final Remarks ==== | ==== Final Remarks ==== |
We do not recommend to use UTCI in the regression-based version for using 2m (1.6m) level wind speeds. In a complex urban environment, wind speeds at pedestrian level are unique and cannot be related to some above-roof general quantity. Instead, we propose the application of a pure phxsically-based approach such as PET. PET is a much more open platform and the final outcomes are more or less the same for all static indicators. | We do not recommend to use UTCI in the regression-based version based on using 2m (1.6m) level wind speeds extrapolated to 10m. In a complex urban environment, wind speeds at pedestrian level are unique and cannot be related to some above-roof general quantity. Instead, we propose the application of a pure physically-based approach such as PET. PET is a much more open platform and the final outcomes are more or less the same for all static indicators. |
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