Does EPW file take daylight savings time into consideration?

  1. No. You can adjust the input hour yourself.

  2. Sunny sky is not a climate-based sky. It’s a standard sky. It only uses the location data from the weather file. If you want to use the values from the weather file then you should use the climate-based sky instead of CIE skies.

Hi Mostapha,
Thanks for your response. Do you mean e.g. if you want the study for 3pm UTC summer in Chicago, just run simulation for 2pm summer to account for the 1 hour daylight savings time difference?

Also if I understand clearly, the sunny sky is the worst case scenario then as it is not considering any cloud cover etc.

Thanks again for all your help.

Hi Ibby,

  1. Yes.

  2. Check this document to learn more about the skies and / or search for “CIE Sunny Sky Radiance”.


I was searching the forum how to read the external illuminance value. I’m pretty inexperienced in these matters, maybe I’m asking a silly question. Can I see how many lux of external illuminance is for CIE Standard sky conditions (sunny, cloudy, etc.)? Doesn’t the values in the weather file (global, diffuse, direct) make any sense?