Annual UDI statistics

Sophisticated 3D simulation of light levels using advanced ray-tracing techniques, covering luminance, illuminance, daylight factors, perceived impact, photorealistic visualisation
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Annual UDI statistics

Postby ahsaaah » Thu Oct 06, 2016 11:28 am

Hi can anyone help me understand what is the statistics in WP Grid means for Annual UDI results.

For % Annual UDI <100 lux for occ 9-17, it gaven

<25% = 651(1116)
25-50% = 267
>75% =155

what is the 4 thresholds try to say? Please advise. Thanks.

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Re: Annual UDI statistics

Postby PCully » Fri Oct 07, 2016 4:11 pm


The Radiance User Guide is up to date describing all of the processing options you have and what results you can assess after running the dynamic simulations. Access this via Help >> User Guides. As they incorporate different variables the results can sometimes be difficult to immediately consider but there are lots of online resources that can help with UDI and I know there is some ongoing debate about the appropriate criteria to apply for the limits so VE does let you choose different thresholds to test against and different time periods as well (occupied hours, 9 - 5 etc)

When you run the analysis and apply the default post process parameters then you will see you get different results file to access on the results tab

% annual UDI < 100 lux
% annual UDI 100 - 500 lux
% annual UDI 500 - 2500 lux

When you select one of these e.g. % annual UDI < 100 lux then view your working plane you can see each grid point is assessed against the criteria to calculate how many hours that grid point achieves average less than 100 lux then we colour the working plane according to if the grid point achieves less than 100 lux for less then 25% of the analysis period, 25 - 50% of the analysis period, 50 - 75% of the analysis period or for greater than 75% of the analysis period. You can then view that assessment for each different lux threshold criteria as required

the statistics summary you have referenced is showing you the number of grid points in each band and the number in brackets is the total number of grid points on your working plane. This way you can convert the number of grid points in your threshold band as a % and get the % floor area that achieves the criteria.

I hope I haven't made any typo here, it's a complex test because there are multiple parameters involved and because it's a simulation run over the year then we have time as a factor to include but industry standard has adopted these metrics as a way to capture all that information in a single number. There is a lot going on so my recommendation is to draw a single deep room with a small window at one end and switch through the different results files to appreciate what they show you and you will develop some more intuition for it (well this works graphically for me anyway :ugeek: )

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Re: Annual UDI statistics

Postby btysoe » Thu Jun 15, 2017 8:35 am

Why are the radiance parameters restricted on the UDI annual simulation? The quality options are simply greyed out so we cannot understand what parameters are being used.

It is fundamental to the calculation to be able to understand what radiance is doing. I understand the impact changing some of the parameters have on the simulation complexity and the cpu time but surely this should be down to us to decide on based on the complexity of the room?

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