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Night Time Heat Stress

Universiteit_leiden 4Universiteit_leiden 4
in Environment

Hi, I am conducting an analysis to find the most effective actions to mitigate the UHI effect. I am using the heat stress module and comparing time frames for different green actions. I noticed that at 10 pm, 11 pm and 6 am buildings are cooler than the courtyard. There is only 1C difference between them but logically green spaces should be cooler than the buildings. However, the results show the opposite. At 10 pm and 11 pm PET values of the building are 39C while the courtyard is 40C. I could not find an explanation for this situation. I checked the wiki page for calculations but that was not helpful either. Is there another website or document to check this problem?

Thank you.

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Comments

  • GodeliefGodelief

    Hi @Universiteit_leiden 4 ,

    I think that you can find the answer to your question on this wiki page: https://support.tygron.com/wiki/Exclude_buildings_(Heat_Overlay)

    Tygron support team

  • Universiteit_leiden 4Universiteit_leiden 4

    Thank you @Godelief. Even I exclude the buildings, I can not explain why the temperature of the courtyard goes up gradually. According to the literature, it should be cool down after 7 pm. However, in my analysis, it keeps going up. For example, a courtyard full of deciduous trees is 34C at 2 pm which is cooler than the surrounding, and the same courtyard is 39C at 11 pm which may be because dense tree canopy absorbs the heat but I got the same results when I replace trees with grass.

  • GodeliefGodelief

    Hi @Universiteit_leiden 4 ,

    Can I take a look into your project to see what is happening? You can give Tygron Support access to your project by going to File in the project and then in the section Edit rights, give Tygron Support read or write access.

    Tygron support team

  • Urbansync 5Urbansync 5

    Hi @Godelief. That would be nice if you can look at it. I have already given the right to write for Tygron Support. I have two account one from the university and the other from a planning company and the project I use in this account.

  • GodeliefGodelief

    Hi @Urbansync 5 ,

    I forgot to ask you, what is the name of your project?

    Tygron support team

  • Urbansync 5Urbansync 5

    Leeuwesteyn2 2 Merve and Rhapsody In West Mrv

  • GodeliefGodelief

    Hi @Urbansync 5 ,

    Thank you for the names. I had a look into the Leeuwesteyn project and noticed that you did not enter any new values in the Heat wizard in step 2. For every hour the temperature, wind speed, sun radiation etc are all the same values which is not realistic and causes the heat stress during the evening.

    To configure the Heat stress overlay, you have to add KNMI data for the date and hours you want to calculate the heat stress for. On our Wiki you can find tutorials on how to do this:

    Does this help you further?

    Tygron support team

  • Urbansync 5Urbansync 5

    Thank you @Godelief. I have calculated all the values manually and added to heat stress configuration wizard. However it changed the situation just a little. Before I changed the values at 11 pm courtyard was 1C hotter than the building, now they have same PET temperature of 39.4C. Also, courtyard temperature still does not go down at night. I have checked the actual temperature values of August 2 2013 and at 11 pm it is 20C. I don't know how to explain this difference.

    I have also another problem. When I changed the building function as green roof, heat stress calculation does not take into account the change. It simply ignores it and assumes the building as bare roof. I tried the change function from measures and also tried the add pairs as suggested in this link https://www.youtube.com/watch?v=_Xln2fhXr0A . But I got the same results. Is there another solution?

  • Urbansync 5Urbansync 5

    Hi @Godelief . I solved the temperature problem. I forgot to change the temperature values in configuration wizard. Now I have more realistic results. But the problem with green roof still continue. How can I solve it?

  • GodeliefGodelief

    (for other users) see this post for an answer to the last question: https://community.tygron.com/forum/discussion/440/green-roof-upgrade

    Tygron support team

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