[Sbse] CU values for LED fixtures

Walter Grondzik gzik at gzik.org
Thu Aug 2 10:11:22 PDT 2018

A question for the listserve --

LED luminaires sometimes show CU values greater than 1.0 for lower RCR 
values. This is physically impossible, but it seems to be an artifact of 
the procedures used to calculate CU.

The question >> what do designers do about this when in the range of RCR 
where a CU might exceed 1.0?

A. just round down to 1.0? (knowing that even this is unlikely)

B. Round even further down? (to say 0.95 or ...)

Followup questions:

(1) is there an industry "standard practice" on how to handle this?

(2) does the calculation quirk that leads to CUs > 1.0 flow through all 
the CU values for a given fixture? (are they all x% higher than 
warranted or compared to a say fluorescent fixture)

Thanks as always.

Walter Grondzik

More information about the SBSE mailing list