Hey @syltetoy and @SaeranVasanthakumar ,
You are correct that the legacy microclimate maps do not use the emissivity of the various surfaces when calculating longwave MRT at each grid point. But, to be more specific about the assumption that’s being made, the microclimate maps are not assuming surfaces have an emissivity of 1. Rather they are assuming that the emissivity of the surrounding surfaces are all comparable.
Bear in mind that it’s emissivity difference that affects the radiant exchange calculation. Not absolute emissivity. If a person is surrounded by surfaces that all have an emissivity of 0.1, you will have the same longwave MRT for the person if the surfaces all had an emissivity of 0.9. I know that feels bizarre but radiant exchange is weird.
In any case, you are right that the microclimate maps should account for emissivity of different surfaces to make them more accurate and I plan to account for this in the LBT plugin (I’m starting to implement the microclimate maps there now). If you really need to account for emissivity now, you can try to hack the legacy microclimate map component and, if you go down this route, I apologize in advance that my code from 5 years ago is so messy.
Or you can try to do your own long wave MRT analysis using the Ladybug view factor component like this example:
Also, for the record the maps do the calculation with the 4 and 1/4 exponents. You can see the specific lines doing the long wave MRT here: