URGENT! LEED v3 NC 2009 Daylighting report inconsistent

Forum for users to discuss the DesignBuilder Radiance daylighting tools and ask questions

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Posts: 24

URGENT! LEED v3 NC 2009 Daylighting report inconsistent

Postby nfonner » Wed Apr 01, 2015 8:09 pm

I am getting very inconsistent answers between the Daylighting Credit - LEED v3 NC 2009 IEQ 8.1 Report and individual zone performance using the same metrics.

Ie. selecting a block vs individual zones for displaying results shows vastly different answers.

See attached files for elaboration. I don't even have to do the math to see that there is an issue with the lower limit.

I did a separate daylighting analysis using Radiance (via OpenStudio) and found the result was 91% passed the threshold requirement. I had to use a spreadsheet to get this done, but at least it made sense.

Is there a way to get at the grid values to manually calculate the performance for IEQc8.1 via the spreadsheet method? The maps are useful only as a graphic unless I can switch on an illuminance grid with data labels.

Daylighting Credit LEED v3 report.pdf
The report seems to have an issue with the lower limit threshold of 10fc.
(67.96 KiB) Downloaded 411 times
1006 - Collaboration User Defined.jpg
Zone level daylighting performance with same calculation parameters defined as Daylighting Credit LEED v3 report.pdf

Area that is not either grey or white should be counted as passing.
1006 - Collaboration User Defined.jpg (61.25 KiB) Viewed 29405 times
Posts: 24

Postby nfonner » Wed Apr 01, 2015 8:53 pm

Possible explanation to developers/ users:

I entered fc using (lux to fc conversion 2x (fc = 0.0929 * lux) even though the input fields request inputs in fc originally.

Eg. original input was 10fc. DB might see 10/0.0929 = 107 fc as the lower limit.

I tested this with lux (si under international program options), but with the same issue.

Note that the upper limit should catch a lot of the area in the attached image below. Setting the upper threshold to 5000fc does nothing for the block report. That is why I believe that the errant conversion above may be the issue here.
1007 - Classroom SE - User Defined.jpg
Southeast classroom with a good portion of the area above the 500fc threshold.
1007 - Classroom SE - User Defined.jpg (61.34 KiB) Viewed 29403 times
Luis Sousa
Posts: 372
Location: Stroud

Postby Luis Sousa » Fri Apr 10, 2015 5:11 pm

Hi Nic,

Could you please raise a ticket at the Support desk and attach your model.


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