# Extacting hourly data from an annual incident radiation calculation

Hi!
I’m new to Rhino/Grasshopper/Ladybug and hope to get some help here.

I’ve made an incident radiation simulation for a building, with the aim to compare possible energy production from photovoltaics to the projected energy consumption of the building.
The yearly output of kWh/m² is great, but it would be great to extract values for each grid point (or mesh subsurface?) and each hour.
So, to put it shortly, is there a way to extract hourly values for the incident radiation calculation?

I’ve already tried finding answers on the forum but wasn’t very successful - most of them weren’t (fully) answered or were relatively outdated:

Worth mentioning:
I have a pretty complex roof geometry and millions of grid points - I have a feeling that it would be way more efficient to visualise results per roof surface, instead of extracting a hefty excel sheet. How can I subdivide the generated mesh into surfaces that correspond to the roof planes? I hope this question is understandable, if not let me know and I’ll try to better specify.

Any help will be greatly appreciated!

Well the short answer is that its relatively easy to get the values.

After running a Annual Irradiance - HB-Radiance Primer simulation, you get the data by using https://docs.ladybug.tools/hb-radiance-primer/components/4_results/annual_results_to_data and using the opportunity to select points, you can select meshes that you want to work with.

But the question is if it is really usefull to have millions of grid points, with 8760 points of data. Perhaps a simpler model would give the same result.

Yeah, yor remark leads nicely into my next question, which is how to simplify the model? Maybe by increasing the grid’s size? Or would there be a way to get an average hourly value over a certain surface? Does the increased grid size do just that or will the simulation just be less accurate?

I can’t think of a building where million of grid points are of any real value.

One solution is to grid some surfaces tightly, if the shading/form is complex, and others more simply.

Or just grid a bit less tightly.

I suggest doing a test where you look at the cumulative sum for some of your more complex surfaces for different grids. Then you will find the grid dependancy.

Unfortunately, this object doesn’t seem to work with incident radiation. Only with the HB Annual Daylight object, which doesn’t output radiation values, only irradiance.

I find that doing incident radiation for PV estimates, is to rough.

This works with HB annual irradiance, which gives a better estimate.

If you want to use only incident radation, you could reduce HOYS in skymatrix and increase your grid to reduce your data.

And perhaps use LB mesh selector to find usable areas.