UTCI Comfort Map. Modelling outdoor evaporative cooling

grasshopper honeybee
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Hi Everyone. I wonder if anyone can share their experience in modelling outdoor evaporative cooling systems or evaporation from the water bodies.

I’m trying to simulate outdoor thermal comfort conditions using the UTCI Comfort Map component and want to evaluate the effect of mist cooling systems or similar. I tried using honeybee thermal zones with air boundaries set for all “external walls” and “roof” but the simulation does not run. I was able to run the model with walls and roof set to be 95% of apertures that are always open and setting the HVAV system to be evaporative cooling, but I doubt that the MRT is calculated properly in this case.

Finally, I’m thinking of using a separate EPW file for the areas with evaporation and setting ambient temperature to something closer to wet-bulb temperature and the combining the UTCI results for non-modified and modified EPW.

However, I wonder if anyone can point me to the right direction or share their thoughts on the topic. Any ideas are much appreciated. Thank you!

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We were talking about this as well but still finding our way. We were considering just changing the albedo values for wet surfaces, to compensate for the cooling effect. There’s literature about how much mist or wet surfaces reduces temperature that can be used to approximate, though maybe pretty roughly. The cooling effect in the air from mist with outdoor misters is so proximal that I think we were considering ignoring it, though not sure what your setup is?

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hi @joshkpeterson, thanks for your reply. Can you point me to the literature on mist/wet surfaces you mentioned?

I’m looking to estimating the effect of systems like this:
Create cool outdoor spaces, maximise seating capacity | CoolMist
Cooling Systems for Public Spaces | Outdoor Misting Solutions- Youmist
Heating and Cooling Solutions Australia | Alfresco Spaces

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A high level approach used at my company for quick analysis is to post process the results for specific areas and adjust the air temperature and relative humidity, e.g assume misting will take the air 30% closer to wet bulb temperature, what’s the impact on air temperature and RH, plug the new numbers in to the UTCI calc to get the adjusted result.

1 Like
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thanks so much @charlie.brooker. This is a great high level approach and I will try using it!