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What does UGR really stand for?


Right now, almost all LED companies claim their Downlight, Panel, Highbay is UGR<19. Definitely, there products is not 100% UGR<19 and many of them are lying. So, we need to know more about UGR and how to get a reliable data! This is the aim of this article.

1.  The Standards and key problems on UGR test reports.

There are 3 standards related to the UGR:

1)  CIE 117-1995: Discomfort Glare in Interior Lighting

This standard tells us how to calculate the UGR and other photometric value, it is written in the goniophotometer software.

2)  EN 13032-Part 1,2,3-2004, EN 13032 Part 4-2015

Part 1: Measurement and file format

Part 2: Presentation of data for indoor and outdoor work places

Part 3: Presentation of data for emergency lighting of work places

Part 4: LED lamps, modules and luminaires

This standard guides how to measure and which format files should be used for reports.

This is the key different for everyone right now, 

especially, the measurement of Luminous Area and the height of the luminaries.

3)  EN12464-1 2011: Lighting of work places - Part 1: Indoor work places

This standard shows how to judge the UGR levels or other parameters. About the Final UGR, it’s depends on projects(size, reflection).

From the above 3 standards, plus over ten years experience in lighting, we find there are 2 BIG problems that may affect the UGR:

A.  One is the goniophotometer created pdf reports(NOT ies/ldt file).

We’ve tested over 20 times with our G1 Panel and Annulight highby in 3rd party labs, including TUV cooperated lab before, but found all their UGR Table in the pdf reports is not the same although with the exactly the same product. But once we put the ies/ldt file in Dialux or Photoview(Oxytech), from different lab with same products, the UGR Table is almost the same. Currently, I am not sure why, but think there maybe something related to the different software. So, this experience tells me not to trust the any PDF reports, but just put all different ies/ldt file and compared at the same system(Dialux, Photoview, AGI32…).

B.  The other is the input Luminous Area of luminaire.

I’ve also read a lot of ies/ldt files from quite a lot of lighting companies, but found a problems that some the Luminous Area input from the test engineer is not follow a standard regulation, for example, in the Fluorescent T5/T8 modular louver panel, Philips lighting put the outer size of all louver(including the size between all louvers), while fagerhult,thorn lighting use the louver size times the louver number. Also, I see most of people put “0” for the height, while some put the height of the luminare. These is the biggest affect on UGR table, in might make a UGR 27 drop down to UGR 19. So, We all need to input a correct data according to the EN 13032. Otherwise all reports are wrong.

2.  A recommended free & easy tool to check IES/LTD files.

There is a very easy software to checked the photometric IES/LDT/CIE format files. You can download the free software--LITESTAR 4D on http://www.oxytech.it/software/download-software.asp?LN=UK

Once installed, you can open the Photoview, and drop/open the files.

Then you can check UGR, Luminance Limit…

In the General Data page, you can see the input data of Power/Luminous Area(all this is input by test engineer, but has big affect on the result of efficacy or UGR), this data should be input according to the EN 13032-4 2015!Next articles will write something about this standard.