Mean Radiation Temperature Problem

Discussions about the Version 4 concerning the core model simulations
Ryan
Posts: 4
Joined: Wed May 29, 2019 6:11 am

Mean Radiation Temperature Problem

Postby Ryan » Fri Aug 23, 2019 2:03 pm

Dear Dr. Tim

I am using the ENVI-met to simulate the microclimate of small open space during summer time.
But after many tests, I still got extremely high mean radiation temperature even up to 58℃ in the afternoon.
(My site is in Shanghai, China)
I changed the solar adjustment factor to 0.55 and 0.65 for tests but it didn't work.
Do you have other advice of settings to reduce the Tmrt.

By the way,
I used Leonardo to visualize the UTCI at 1.4m height
but there are some empty area(UTCI=-999) outside the building
What's the problem?
(The images are attached)

Regards,
Ryan
Attachments
MODEL SPACE.png
UTCI.png

Tim
Posts: 1203
Joined: Mon May 15, 2017 3:46 pm

Re: Mean Radiation Temperature Problem

Postby Tim » Fri Aug 23, 2019 4:09 pm

Hi Ryan,

I wouldn't say that MRT values of 58 °C are wrong in general. Depending on the building materials in the model area, it may show such high values. I would not recommend to change the solar adjustment factor, since radiation is calculated correctly for the position of your model area. You may rather use clouds or put in measured radiation values by FullForcing in order to manage the solar radiation.

The -999 values for UTCI only appear, if it could not be calculated for the specific cell. Most often it happens, when the cell is located inside an object such as a building or terrain cell, or any of the calculation parameters such as wind, air temperature or one of the others is corrupted for that cell.

Best regards,
Tim

enviadmin
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Location: Essen/ Germany
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Re: Mean Radiation Temperature Problem

Postby enviadmin » Mon Aug 26, 2019 3:18 pm

For UTCI:
UTCI is not defined for wind speeds below 0.5 m/s (see Biomet website)

Michael


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