Ladybug vs Archicad sun

[taiho]

Hello all,

after doing shadow analysis in ladybug and archicad, I see the deviation (~10°) between these results. I dont know which standard and algorthm that archicad uses and which one is more precise?

both use the same model (export from archicad), set up same location, north axis.

Operating system used: Windows

[Barry Kelly]

The same date and time and allowing for daylight saving or not?

Barry.

[taiho]

Hello,

I used the same model for both, same location position, same timezone, north axis etc..

Sorry that I can not upload the file (.pln or .3dm) based on confidental of my office. Please just have a look at the screenshot above.

Thanks.

[Barry Kelly]

The same model may not mean the same location, time and date in each software.

In Archicad you must set the north point. longitude & latitude, date & time to get the correct shadows.

I am not sure that these are transferred with the model.

I don't know anything about Ladybug, but I am wondering if you have to set those same values there as well.

Barry.

[scottjm]

Can you compare the altitude and azimuth of the sun between Archicad and Ladybug for a few specific date/times. 
I would cross reference them against same online sun angle calculators to see if one (or both) are different. 
I presume there is a defacto formula that exists for calculating sun angles based on a specific long/lat.