Hello everyone! I’m a university student in Japan and studying multi-node thermal comfort models.
I read the two materials, “A new modeling approach for the assessment of the effect of solar radiation on indoor thermal comfort” written by Andrea Zani and “Employing Radiance in Thermal Comfort Simulations involving Complex Fenestrations” written by Sarith Subramaniam, and was very impressed!
So I’m trying to get irradiance values (W) on each parts of the body.
I have a question about that.
Can I get irradiance values(W) using only Honeybee[+] DC Grid-based Daylight Recipe component without additional Python or Radiance source code?
The DC grid-based recipe calculates illuminance by default. So, you’d have to change a few things in the final .bat file that is written out by Honeybee[+] (mostly disabling the conversion from irradiance values to illuminance).
I think other than that, it should work provided that you are only considering direct radiation from sun and sky to the manikin. Values for reflectance typically tend to be assigned for lighting calculations, so any consideration of that in thermal comfort simulations is likely to be incorrect.
@sarith
Thank you very much for the reply. It was very helpful!
If you don’t mind, there are two more thing I’d like to ask you.
1.What is the unit of irradiance obtained from DC method results?
In the DC grid-based recipe, the unit is expressed in solar energy [kwh/m2], while in the two materials I read, the unit is expressed in peek power[W/m2](epw file data includes irradiance value [Wh/m2]). I need the peek power [W/m2] to determine thermal comfort.
2.Is it suitable to use the DC grid-based recipe in outdoor?
I got results of irradiance values in outdoor, but some values became so high when I changed final .bat file. Please let me know if my flaw of the convertion is obvious.
The unit of illuminance, which is what the DC script calculates, is lux (or lumens per sq. m). The weighting factors c:\radiance\bin\rmtxop -c 47.4 119.9 11.6 are used to convert Watts/sq. m to lumens/sq. m. So, to answer your query…
… the units are in Watts/sq. m (If remember this correctly!).
Regarding this…
… I think it is fine to use the recipe outdoor. The higher values are likely because there is no shading occurring.
By the way, the commands that begin with echo are just comments and have no bearing on the simulation. So, you need not bother changing anything here: echo :: :: rmtxop -c 0.33 0.33 0.34 [results.rgb] ^> [total results.ill]
Is there a reason that you have bumped up the blue channel to 0.34 (instead of 0.33). It might be better to set each of the values to 0.333333 instead of having a slight imbalance in one of the channels. It is unlikely to matter much anyway.
Hope you’re well.
I’m picking up on one of your replies " Values for reflectance typically tend to be assigned for lighting calculations, so any consideration of that in thermal comfort simulations is likely to be incorrect".
Could you please clarify how you mean that the results out of radiance for incident solar radiation (direct+diffuse+reflected) would be incorrect?
I’ve always assumed the irradiance calculated is the sum and corresponds to what an occupant would experience physiologically (topping up the operative temperature).
Long-wave radiative transfer is ignored in radiation-only calculations. The radiation from the sun and sky that is directly incident on the human body mostly falls within short and medium-wave. But once this radiation strikes the surfaces (building/ground etc) the reflected radiation also has a long-wave element to it. As far as I know, this long-wave component is not being accounted for in most tools/workflows.
Darren Robinson, the creator of GencumulativeSky, had discussed this at length in his 2004 paper on urban radiation.
The above figure is taken from that paper, and the part that is highlighted in red is soemthing that we arent doing right now. Although his discussion relates to urban contexts, same principles will apply to indoor manikin-related calculations too.
