Question about the difference between UDI results from HB Annual Daylight and manual calculation

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1

Hi everyone,

I hope you’re all doing well.
I have a question about the UDI (Useful Daylight Illuminance) results calculated using the HB Annual Daylight component.

When I try to extract the hourly illuminance values to manually calculate the UDI, the results are quite different from those given by Honeybee. I’ve tested two approaches:

  1. Calculating the UDI for each sensor point individually and then averaging across all points.
  2. For each hour between 8:00 and 18:00, calculating the average illuminance of 12 indoor sensor points, counting how many of these hourly averages fall within the 300–3000 lux range, dividing that number by 12, and then averaging over all hours.

However, neither of these methods gives the same result as HB Annual Daylight.
Could someone please help me understand why there’s a difference between the built-in calculation and my manual method?

Thank you so much for your time and help!

Best regards,

2

This is the battery situation.
https://youke1.picui.cn/s1/2025/11/11/69134d4f98d42.png

3

Hi @Alice2 , from the screenshot you shared, it does not seem that you have set custom “threshold” to your annual simulation. By default UDI will be between 100-3000, not 300-3000.
Apologies if I understood your screenshot wrong.

4

Thank you so much! And I also realized that there was a problem with my analysis time period; the default 8-18 should be set to 8-17 in the period settings.