Sunlight hour analysi LB vs Shadow range study HB


Folks I am confused. Please help clarify what is the difference between the ‘Sunlight hour analysis’ done via LB vs ‘Shadow range study’ done using HB/ Radiance.

On Hydra I found a ‘Sunlight hour analysis’ script which uses a LB component. (see screen capture 1 below). This gave me a wonderful butterfly diagram so I can explain how many hours of sunlight the street or plaza etc will get. (see screen capture 2 below)

Next on Hydra I found the ‘Shadow range study’ which uses HB (see screen capture 3 below). I saw a you tube video where Mostapha showed how to run this script (see screen capture 4 below). I was able to run the script and get a HDR image.

My question is what is the difference between these two? Can I extract any sunlight/ shadow values from the HB HDR image or is this just a pretty looking visual? I mean how is this informing my design? What should I learn from it.


Screen Capture 4 attached.

The sunlightHourAnalysis allows you to get the butterfly diagram you (and everyone) like.

The shadow range study (via HB) allows you to produce individual images for each requested hour.

What you learn from any of them? Depends what you want to ask. Some analysis allow you quality evaluation and some quantity, and some both.



Thanks for the response. So now I understand the HB HDR visual goes hand in had with the LB sunlight hour analysis.

I have a follow-up question. Can I run a sunlight hour Analysis for 1 day using HB/ radiance and display the results on a base plane grid and get result similar to the LB component?

I want to use HB/ radiance as it is faster than the LB component when I use Accelerad.


I believe this is a post processing thing, either photoshop or using radiance functions (not an expert but there is a pcomb command).

Radiance is faster (or slower) depending on the settings you define (resolution, image size, and many more …).


I have a question. Does “Ladybug_Sunlight_Hours Analysis” component consider everyday is sunny day? What if my city only has 100 sunny days?

I’ve made a sunlight hour analysis and wanted to know the places that has more than 30% of daytime that is in shadow.

It’s a good question. You can do that considering that you can define what a “Sunny” day is for your climate. You can define this either in terms of direct normal radiation (If this number is greater than or equal to X then it’s considered “Sunny”) or in terms of total_sky_cover (If this number if less than or equal to X then it’s considered “Sunny”). Both these variables are found on Import_EPW component. Once you have this list, you can craft sunpath for those “Sunny” days.


Interesting @devang.
I will check alsothe direct vs diffuse radiation. There are places with very high diffuse.

Absolutely true. Thanks for adding that.