I’m looking into external comfort, found two examples on Hydra
- Urban Microclimate - Simple Spatial UTCI - found here
- Outdoor Microclimate Map - found here
I understand the first is simpler and does not require energy simulation. It’s also mentioned that it doesn’t take into account spatial differences in wind speed. I can see however that the UTCI calculator has wind speed as an input.
Would someone explain to me or point me in the direction to find the difference between the two scripts please and why there are like ‘external zones’ in the 2nd script in-front of the buildings?
The simplified explanation is that the first is modifying the MRT input to account for varying solar radiation in site (but not accounting for long wave radiation exchange from the sky and environment surfaces), the second is modifying the MRT input using surface temperatures from EnergyPlus and bespoke view factors that accounts for long and short wave radiation exchange in the site.
There’s a better, more detailed explanation in this paper (published by Chris, Theodore, Mostapha etc) that goes into detail about the different ways to modify the UTCI inputs to represent urban microclimates: http://www.ibpsa.org/proceedings/BS2017/BS2017_260.pdf. It doesn’t address the Hydra scripts directly, but I think you’ll understand the difference better once you read the paper.