LBT Real Time Incident Radiation

Hie all,

I am discovering the LBT and I find it great. Thanks a lot.

I have one question though : I want to produce 12 monthly incident radiation analysis on a single geometrical model. Reading the component help, I understood that Cumulative Sky Matrix provides results hour per hour, but looking in the resulting data trees with param viewer, lead me to understand that, it is, as the component name says a “cumulative” sky matrix.
Have I got to place 12 Cumulative Sky Matrix components, one for each month an d cross them with intersection matrix, or is there a more short and elegant way of doing this ?

Hi @FrehelDenis,
If you use LB Deconstruct Matrix component, you will see that the component produces a header (brach1) direct (branch2) and diffuse(branch3) components for the Perez sky (145 sky patches). You will see that in both branches 2 and 3 there are 145 values. These are total direct and diffuse component totaled for the hours of the year you select on analysis period.

The image below shows the values for one day.

The image below shows the values for one month.

If you observe the 9th items on the second branch, you will the increase in value when we look at the whole month.

For your analysis, you will be able to do the analysis by changing the months on the analysis period component. It will be 12 simulations.

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Hi @devang. Running into a similar issue and wanted to question whether the Deconstruct Matrix is really producing totals for each hour of the analysis period. I just tried an analysis period of Jan 1 to Jan 31 (744 hours), and Jan 1 to March 31 (2160 hours) and both runs produce 145 values for the two branches. Is it possible that each of these two branches are producing the cummulative values for the sky matrix? If so, then what is the best workflow to use the Real Time Radiation Analysis component to get hourly radiation values? In Legacy, we were able to the use selectSkyMatrix to create a hourly sky matrix and plug that into the Real Time Radiation Analysis component but that doesnt seem like an option during v1.1-v1.2. Thanks!

I just found this recent post addressing what I am asking. I will copy here for others to follow:

Hopefully we can bring back the ability to parse hourly radiation values just within Ladybug and not in Honeybee. Regardless, v1.1 and v1.2 is amazing!

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hey @KitElsworth, glad that you found a solution. I believe we will be able to do that.

Hi @KitElsworth. A possible workaround to get the hourly values would be to run the Radiation Analysis with a full year setting (default) but input individual sky_mtx for each hour into the Real Time Radiation Analysis component. Warning: the generation of all 8760 skymatrices may take some significant calculation time. Cheers!

That can certainly do the trick, @gsjacomini , but, if you are willing to wait that long, it’s probably faster to just run a HB Annual Irradinace simulation and use the HB Annual Results to Data component to import the hourly values. That method will also allow you to account for reflected solar energy unlike the workflow here.

Also note that, if your study doesn’t have any context geometry and you’re not concerned about self-shading, you can instantly get the hourly irradiance of a surface facing any direction using the LB Directional Irradiance component.

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