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Hi @hema, I'm assuming you have daylight illuminance data. Calculating UDI with this is as simple as binning the data into those timesteps that meet the UDI criteria, and that which does not. Originally UDI (Useful Daylight Illuminance) was considered met for the timestep if it was between 100 and 2,000 lux. More recently the upper threshold has been raised to 3,000 lux, owing to the fact that most computer monitors these days are flat (shape) and matte (finish). Therefore, all you need to do is take your data and "score" each timestep depending on whether it meets the UDI criteria or not.

That said, UDI is a so-called dynamic daylight metric, and is really intended to be used in a climate based daylight modeling modality, which implies you have at least hourly data for the entire year.

P.S. OpenStudio calculates UDI on a per-space and a whole-building basis for you if you use Radiance as the daylight simulation tool.

Hi @hema, I'm assuming you have daylight @hema,

OK, so that idf file is giving you daylight illuminace data for all the illuminance data. Calculating maps, which is sounds like you've already gotten out of the eplusout.sql file and into xls, or csv format. Great. At that point, calculating UDI with this is as simple as binning the data into those timesteps that meet the UDI criteria, and that those which does do not. Originally UDI (Useful Daylight Illuminance) was considered met for the timestep if it was between 100 and 2,000 lux. More recently the upper threshold has been raised to 3,000 lux, owing to the fact that most computer monitors these days are flat (shape) and matte (finish). Therefore, all you need to do is take your data and "score" each timestep depending on whether it meets the UDI criteria or not.

That said, UDI is a so-called dynamic daylight metric, and is really intended to be used in a climate based daylight modeling modality, which implies you have at least hourly data for the entire year.

P.S. While OpenStudio calculates UDI on a per-space and a whole-building basis for you if you use Radiance as the daylight simulation tool.

Hi @hema,

OK, so that idf file is giving you daylight illuminace data for all the illuminance maps, which is sounds like you've already gotten out of the eplusout.sql file and into xls, or csv format. Great. At that point, calculating UDI with this is as simple as binning the data into those timesteps that meet the UDI criteria, and those which do not. Originally UDI (Useful Daylight Illuminance) was considered met for the timestep if it was between 100 and 2,000 lux. More recently the upper threshold has been raised to 3,000 lux, owing to the fact that most computer monitors these days are flat (shape) and matte (finish). Therefore, all you need to do is take your data and "score" each timestep depending on whether it meets the UDI criteria or not.

That said, UDI is a so-called dynamic daylight metric, and is really intended to be used in a climate based daylight modeling modality, which implies you have at least hourly data for the entire year.

While OpenStudio calculates UDI on a per-space and a whole-building basis for you if you use Radiance as the daylight simulation tool, the Radiance support does not currently include support for BSDFs. This is in the works, however and will be in the OS GUI this year (and will be usable via a measure even sooner).