.epw files used in UWG

[aleksandraradecka1]

Hello,

I am using the UWG module, and in order to make the results more accurate I decided to replace the epw. file downloaded from https://energyplus.net/weather with the file created myself based on ERA5. My colleage prepared the file according to the instructions found in the first tutorial https://umep-docs.readthedocs.io/projects/tutorial/en/latest/Tutorials/DailyShading.html#dailyshading I am not sure however if the two files - the tutorial file and .epw, containing meteorological data are anyhow comparable.

I would be very greatful for some advice on this.
Best regards,
Aleksandra

[biglimp]

I am not sure I follow. There is no meteorological data used in that tutorial...

[aleksandraradecka1]

Sorry if I named this wrongly. I meant the file named "GBG_TMY_1977.txt." (inside "Goteborg_SWEREF99_1200.zip")

[biglimp]

Ok. Yes, they are comparable in the sense that they boty include meteorological data for one year with hourly resolution. The relevant parameters are also the same (Ta, RH, Kdown, Kdir, Kdiff etc.). What you need to consider also the timing (UTC) the data and the ground temperature in the header. Personally I dont think this is super important but I have not tried out the sensitivity for this parameter.

[aleksandraradecka1]

OK, this is a bit relieving for my colleague. The variables' names are different at the first sight, but I understand they mostly describe the same variables. We will work on this. Thank you for your help.

[aleksandraradecka1]

Dear Fredrik,

we are in the process of preparing the new version of .epw file based on ERA5 and one additional question arised: Which of the variables consisted in the file (header info and columns) are anyhow used by UWG algorithm? I of course know that their impact on the final UHI's intensity is still to be assesed.

I would be greatful for the help.

[biglimp]

I think these are the ones (pyid is the python column number, i.e. 6 mean 7th column):

WEATHER FORCING
var pyid num unit
Temp 6 float degC
dewpoint 7 float degC
Relhum 8 float %
Pressure 9 int Pa
Ldown 12 float Wm-2
Kdown 13 float Wm-2
Kdir 14 float Wm-2
Kdiff 15 float Wm-2
Wdir 20 float deg
Ws 21 float ms-1

[aleksandraradecka1]

Thanks a lot! Does it also mean that the header info may be neglected? I remember you mentioned the ground temperatures a few posts ago and therefore I was prepared for working on the header too. Of course if you do not have the answer at hand please do not bother yourself working on this - I will make the required experiments and find out.

[biglimp]

@j3r3m1 , didn't you retreive ground temperature data from ERA5 to be included in an epw-file?

[j3r3m1]

Right ! There is indeed 4 levels of soil temperature available in the ERA5 data) :

• level 1 : 0.035 m
• level 2 : 0.175 m
• level 3 : 0.64 m
• level 4 : 1.94 m

From what I have found about EPW, the number after GROUND_TEMPERATURE are well defined in this page (I have put below the needed informations):

GROUND TEMPERATURES,
N1, Number of Ground Temperature Depths
N2, \field Ground Temperature Depth 1
\units m
N3, \field Depth 1 Soil Conductivity
\units W/m-K,
N4, \field Depth 1 Soil Density
\units kg/m3
N5, \field Depth 1 Soil Specific Heat
\units J/kg-K,
N6, \field Depth 1 January Average Ground Temperature
\units C
N7, \field Depth 1 February Average Ground Temperature
\units C
N8, \field Depth 1 March Average Ground Temperature
\units C
N9, \field Depth 1 April Average Ground Temperature
\units C
N10, \field Depth 1 May Average Ground Temperature
\units C
N11, \field Depth 1 June Average Ground Temperature
\units C
N12, \field Depth 1 July Average Ground Temperature
\units C
N13, \field Depth 1 August Average Ground Temperature
\units C
N14, \field Depth 1 September Average Ground Temperature
\units C
N15, \field Depth 1 October Average Ground Temperature
\units C
N16, \field Depth 1 November Average Ground Temperature
\units C
N17, \field Depth 1 December Average Ground Temperature
\units C
\note repeat above (N2-N17) to number of ground temp depths indicated
-- etc to # of depths entered

I think with this information you should be able to derive the monthly average ground temperature for each level from the ERA5 data and fill the needed "columns in the header". We did not test the influence of this parameter but I am not sure it would affect the results. Let us know if so !

[aleksandraradecka1]

Sorry for the late reply. Thank you very much for your help 👍 Of course, after finishinig with the experiments I will let you know about the details (by mail probably).