Just raising an observation about using the HB Annual Irradiance recipe in the case of conducting Outdoor Comfort studies where test plans are generally taken at 1.1m above ground.
Although the recipe was developped for accuracy and to include Direct+Diffuse+Reflected contributions, it appears that users need to simulate the results for both the test plane facing up and the test plane facing down, before adding them together in order to include the reflected solar radiation from the ground.
NB: when designing urban spaces, the ground’s finishings can be really diverse and various reflectances affect the results considerably.
I had made the same observation when running outdoor solar radiation studies in Sections where I needed to double the test surface and flip them in opposite directions before collecting the results and adding them respectively. I am aware that is a specific and particular use of the recipes.
However in the case of outdoor comfort studies, this may be interesting for other users to be aware of this.
Perhaps the recipe could offer the option for users to double the test points to account for the reflection from below the test surface and offer a way to post process the results accordingly to recolor the mesh correctly, notifying that it doubles the simulation time…
Or maybe the solution would be to simply raise this matter in the recipe description for any user (beginner or advanced) not to forget to account for the solar radiation reflected from the ground.
This is why I would typically recommend people use one of the comfort mapping recipes (eg. HB UTCI Comfort Map) to model thermal comfort since all 3 comfort mapping recipes will automatically format the sensors so that you run the Radiance simulation with the sensors facing both directions. Also, all comfort mapping recipes will feed the irradiance results of the two directions into the SolarCal model so that you get an accurate representation of the solar radiation that would fall on a human geometry located at the sensor point (including all direct, diffuse, and reflected solar irradiance).
For this reason, I’m not planning to change the HB Annual Irradiance component. While the Annual Irradiance recipe certainly could be used to make a “deconstructed” version of the comfort maps, the primary use case that it addresses is more to do with things like peak irradiance on windows and metrics like peak cooling load.
So just use the comfort mapping recipes if you need a streamlined way to simulate irradiance for thermal comfort studies.
@chris would this also give an accurate estimate of outdoor surface temperature? Accounting from reflected radiation from context glazed facades? I remember there was a way you shared on Hydra back in the days for that
It’s a little tough to understand exactly what you are asking because you talk about urban surface temperature, which is primarily part of the long wave calculation, but then you seem to reference shortwave solar reflections, which are obviously a part of the shortwave calculation.
The longwave environment in the comfort maps is still modeled using a combination of EnergyPlus to get surface temperatures and the sky temperature from the EPW.
For the MRT delta experienced by people because of shortwave solar falling or being reflecting onto them, all of the comfort mapping recipes of the LBT plugin use Radiance to estimate this. So, yes, shortwave solar reflections onto the human subjects are now accounted for, if that is what you are asking.
