Question About Long-Wave MRT Calculation in Outdoor Solar MRT (LBT 1.9)

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Hello everyone,

I have a question regarding the long-wave MRT calculation in the current Ladybug Tools (v1.9) workflow.

From my understanding of the current implementation:

  • LB Human to Sky Relation calculates sky exposure (sky_exposure) and fraction of body exposed to direct sun (fract_body_exp).

  • LB Outdoor Solar MRT requires a single _surface_temp input together with solar and infrared radiation data.

  • The workflow does not appear to explicitly calculate view factors between the pedestrian and individual surrounding surfaces (e.g., walls, roofs, and ground).

Therefore, I am wondering whether the current SolarCal workflow should be considered a simplified MRT approach rather than a full long-wave radiative exchange model based on:

image
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where (F_i) represents the view factor between the pedestrian and each surrounding surface, and (T_i) represents the corresponding surface temperature.

Is this interpretation correct?

If so, for users interested in a more physically rigorous long-wave MRT calculation that explicitly accounts for:

  • ground surface temperatures,

  • wall surface temperatures,

  • roof surface temperatures,

  • view factors between pedestrians and surrounding surfaces,

is there a recommended workflow within the current LBT 1.9 ecosystem?

The previous Microclimate Map / Outdoor Comfort Recipe workflow appears to have been removed from the newer versions, so I am curious whether there is currently a recommended approach for performing rigorous urban MRT calculations.

Thank you very much for your time and guidance.