Mean Radiant Temperature (MRT) calculation using Honeybee surface temp and Ladybug SolarCal

@chris

Thanks for your response, it’s very helpful for me!

I’ve had a look at the “HB Adaptive Comfort Map”, however I’m a little hesitant to use it, since here and here I’ve read about the limitations regarding the calculation of longwave MRT using Energyplus that are still present in LBT 1.2.0 (assumption of standing in an open field).

Therefore, my idea was to combine the method for calculation of longwave MRT with the “Ladybug_MRT Calculator” from Legacy (using Energyplus surface temperatures and the long-wave sky temperature (as shown in this paper), with the formulas in the LBT SDK to account for shortwave radiation.

Following your advice, I’ve used the “HB Annual Radiation” component to get the direct and indirect irradiance (using an upward facing sensor grid) and to get the ground-reflected irradiance (using a downward facing sensor grid). (See script: MRT comparison Radiance methods.gh (752.8 KB) ). Do you think this is a correct way of setting up the MRT calculation?

To me, the results seem quite sensible. However there’s one thing that makes me doubt whether I’ve set up the Radiance calculation correctly: In the first method, when I change the reflectivity of the ground by using an opaque modifier (see figure below), the MRT results barely change. However, using the second method, when I change the reflectivity directly in the python formula, the MRT results show quite large differences.

So, there clearly is a discrepancy between the two methods (which can also be seen from the differing MRT results for a similar reflectivity of 0.3, see figures below).

Which method do you think gives more accurate results? And is the set-up of the “Annual Radiation” workflow for Radiance correct like this, with upward sensors for direct and diffuse horizontal irradiance and downward sensors for ground reflected irradiance? (I’m aware that in the Radiance calculation I’ve ignored the windows for now).

Thanks in advance for your help!