I’m currently working with Honey Bee for building performance simulations, and I have a question regarding the calculation of total and direct solar radiation. I’d appreciate some clarification on the following:
Total Solar Radiation: I understand that I can obtain the total solar radiation from the ‘radiation’ output. However, I would like to confirm that this value represents the cumulative solar radiation received at a specific location over a given period, typically expressed in kilowatt-hours per square meter (kWh/m²) per year.
Direct Solar Radiation: I am using the ‘res_direct’ output to obtain direct solar radiation values. Could someone confirm whether ‘res_direct’ represents instantaneous direct solar radiation values? If so, how can I aggregate these values to obtain the cumulative direct solar radiation for a specific time period (e.g., annually)?
Indirect Radiation: I’ve been calculating indirect radiation as the difference between total and direct radiation, which should include diffuse and reflected radiation. However, I want to make sure that the ‘radiation’ output indeed represents the sum of direct and diffuse radiation. Can someone confirm if this is the case in Honey Bee?
it will be over the whole year if that’s what your Wea is for
The irradiance values are in W/m2 but, if your simulation is at the default hourly timestep, then just summing these hourly values will give you radiation in Wh/m2. You can use the HB Annual Cumulative Values components to sum these results.
Yes, this is true:
Subtracting the direct from the total will give you diffuse.
Thanks @chris
It’s quite clear now but there is one other problem I can’t get an explanation for. I don’t know if I am missing something
I’m currently assessing the solar radiation received by a large urban area comprising around 300 buildings. I’ve noticed significant differences of up to 200% between three simulations of global radiation from 7 am to 7 pm (the biggest differences are at 1 pm). These variations seem to stem from the stochastic nature of Radiance.
My queries are:
Understanding Radiance’s Stochastic Behavior: Given the inherent stochastic nature of Radiance, could these substantial differences—up to 200%—between simulations be attributed solely to the software’s stochastic behavior?
Mitigating Stochastic Effects: Is there a recommended approach or technique to mitigate or minimize the stochastic effects in Radiance simulations for more consistent solar radiation estimations?
Optimizing Parameters for Consistency: While acknowledging Radiance’s stochastic nature, are there specific parameters or settings within the software that can be adjusted or optimized to achieve more reliable and consistent results?
Seeking advice on how to mitigate these discrepancies and enhance the accuracy of my analysis. Any insights or suggestions would be greatly appreciated!
