42 Partners - Relux - Lighting Calculations - UGR & Glare

Background:

The ruling standard for lighting is EN 12464-1:2011 because it is the latest relevant EuroNorm.
This says "...The rating of discomfort glare ... shall be determined using the CIE Unified Glare Rating (UGR) tabular method..."
"...variations of UGR ... can be determined using the comprehensive tables for different observer positions, as detailed in CIE 117-1995..."

There are three UGR calculation methods in Relux:

1. Table (tabular) method, this is a single value that is interpolated from the standard UGR table, it is automatically reported in the result overview (under Diversity) when permitted by the standard. This tabular method is specified in the standard but is only valid for a regular array of luminaires, if there is even one additional luminaire in the room that is not part of the regular array, the tabular method is not valid and Relux does not display a result. For information: if the room contains more luminaires than the maximum in the table, Relux reports the value from the maximum in the table, it does not extrapolate beyond the table maximum.
UGR tables are a design aid to assist when manually assessing glare, the calculation results are dependent on the number of luminaires in the calculation area, which is dependent on the luminaire spacing (larger spacing results in fewer luminaires being considered).
EN-12464 stipulates that CIE-117 should be used to calculate UGR tables.
CIE-117 calculations for UGR tables are based on a spacing ratio of 0.25 - this is the default for Relux.
It is possible to specify an alternative spacing ratio of 1 in Relux which will give a glare table with much lower values (similar to old UK TM10 values):
[UGR table] [right click] [property dialog] (see pop-up screen shot)
however this is not in accordance with the EN-12464 standard, and has no relevance to the Relux calculated glare for the installation.

2. Observer points method, this is a method where the lighting designer can specify observer positions and viewing directions. The formula used to calculate UGR in this manner is specified in the standard. When Relux calculates glare for an installation using this method, (Calculation manager - Glare rating) the actual layout is used, not the simplified layout used for tables. This allows Relux to report UGR values where there is no regular array of luminaires and the table method is therefore inapplicable.
To set up an observer point in Relux:
[Calculation manager] [Glare rating] [UGR] (see pop-up screen shot)
Fill in the required observer position(s) and direction(s) of view in the dialogue box [Start].
The Observer icon will be shown in the floor plan view (see pop-up screen shot)

3. UGR grid method, this is a method where the lighting designer can specify a grid of observer points, and results are given for each grid point in viewing directions that are parallel and perpendicular to the room Y-axis. The formula used to calculate UGR for each point is the one specified in the standard. When Relux calculates glare for an installation using this method, the actual layout is used, not the simplified layout used for tables.
To set up a grid of observer positions in Relux:
[Calculation manager] [Measuring Areas] [Reference Plane] [select] [UGR table] [Check Box] (see pop-up screen shot)
Fill in the details of the required grid [OK].

There are problems with the standard EN 12464-1:2011
(opens in a new window)
A Glare seminar is being arranged at the The Lighting Industry Association.
Glare Seminar details and booking information (opens in a new window)
Relux training courses in association with The Lighting Industry Association.
Relux training courses in association with The Lighting Industry Association. (opens in a new window)