Dobbins JLUS IMP Public Draft Light Pollution Study | Page 268

MODEL LIGHTING ORDINANCE - USER’S GUIDE
MODEL LIGHTING ORDINANCE - TEXT
IX. TABLES - TABLE C BUG RATING - User’s Guide
Work on the BUG system started in 2005 when the IES upgraded the
roadway cutoff classification system. The original system, which
included the ratings full cutoff, cutoff, semi-cutoff and non cutoff, had
been designed as a rating system focused on brightness and glare control.
However, with increasing demand for control of uplight and light trespass in
addition to glare, IES realized that a more comprehensive system was
needed. IES developed TM-15 Luminaire Classification System for
Outdoor Luminaires.
As this is a relatively new rating system, and many people may not be
familiar with it, more explanation of how the rating system works is
provided here. For example, some people are familiar with terms such
as “full cutoff” and they may expect the MLO to include those terms.
It will be very important that all groups recognize that older terms and
concepts are inadequate for the complex tasks of controlling light
pollution. It is recommended that the new rating system adopted in
TM-15, as followed herein by the MLO, be used intact and exclusively.
BUG requires downlight only with low glare (better than full cut off)
in lighting zones 0, 1 and 2, but allows a minor amount of uplight in
lighting zones 3 and 4. In lighting zones 3 and 4, the amount of allowed
uplight is enough to permit the use of very well shielded luminaires
that have a decorative drop lens or chimney so that dark sky friendly
lighting can be installed in places that traditional-appearing luminaires
are required. BUG typically cannot be used for residential luminaires
unless they have been photometrically tested. For non-photometrically
tested residential luminaires, shielding description is used instead.
The lumen limits established for each lighting zone apply to all types
of lighting within that zone. This includes, but is not limited to, specialty
lighting, façade lighting, security lighting and the front row lighting for
auto dealerships. BUG rating limits are defined for each luminaire and
USER’S GUIDE - Page 26
Page B-26
IX. TABLES (cont.) - Ordinance Text
Table C - Maximum Allowable Backlight, Uplight and Glare
(BUG) Ratings
May be used for any project. A luminaire may be used if it is rated for
the lighting zone of the site or lower in number for all ratings B, U and G.
Luminaires equipped with adjustable mounting devices permitting
alteration of luminaire aiming in the field shall not be permitted.
Lighting Lighting Lighting Lighting Lighting
Zone
Zone
Zone
Zone
Zone
0
1
2
3
4
TABLE C-1
Allowed Backlight Rating*
Greater than 2 mounting
heights from property line B1 B3 B4 B5 B5
1 to less than 2 mounting
heights from property line
and ideally oriented** B1 B2 B3 B4 B4
0.5 to 1 mounting heights
from property line and
ideally oriented** B0 B1 B2 B3 B3
Less than 0.5 mounting
height to property line
and properly oriented** B0 B0 B0 B1 B2
*For property lines that abut public walkways, bikeways, plazas, and
parking lots, the property line may be considered to be 5 feet beyond
the actual property line for purpose of determining compliance with
this section. For property lines that abut public roadways and public
transit corridors, the property line may be considered to be the center-
line of the public roadway or public transit corridor for the purpose of
determining compliance with this section. NOTE: This adjustment is
relative to Table C-1 and C-3 only and shall not be used to increase
the lighting area of the site.
** To be considered 'ideally oriented', the luminaire must be mounted
with the backlight portion of the light output oriented perpendicular
and towards the property line of concern.
ORDINANCE TEXT - Page 26
Appendix B: Model Lighting Ordinance