Dobbins JLUS IMP Public Draft Light Pollution Study | Page 254

MODEL LIGHTING ORDINANCE - USER’S GUIDE
PRESCRIPTIVE METHOD - User’s Guide
also allow a prescriptive method for classes of sites, such as car dealerships,
gas stations, or other common use areas.
Note that the values are for initial luminaire lumens, not footcandles on
the target (parking lot, sidewalk, etc). Variables such as the efficiency
of the luminaire, dispersion, and lamp wear can affect the actual
amount of light so the lumens per square foot allowance is not equal
to footcandles on the site. By specifying initial luminaire lumen values,
it is easier for officials to verify that the requirement is being met. Initial
luminaire lumens are available from photometric data. Each initial
luminaire lumens calculation should be supplied on the submittal form.
Solid state luminaires, such as LEDs, do not have initial lamp lumens, only
initial luminaire lumens (absolute photometry). Other luminaires tested
with relative photometry will have initial luminaire lumens which can be
calculated by multiplying initial lamp lumens by the luminaire efficiency. In
this example, three types of luminaires are used to light a parking area and
building entry in a light commercial area. Two of these three luminaires use
metal halide lamps: 70 watt wall mounted area lights and 150 watt pole
mounted area lights. For these, the Initial Luminaire Lumens is equal to the
initial lamp lumens multiplied by the luminaire efficiency. These values are
entered into the compliance chart. The lumen value for the building
mounted LED luminaires is equal to the lumens exiting the luminaire.
Therefore, the value already represents the Initial Luminaire Lumens and
no luminaire efficiency is needed. The total Luminaire Lumens for the site
is equal to 247,840.
MODEL LIGHTING ORDINANCE - TEXT
IV. NON-RESIDENTIAL LIGHTING (cont.) - Ordinance Text
A. Prescriptive Method
An outdoor lighting installation complies with this section if it meets the
requirements of subsections 1 and 2, below.
1. Total Site Lumen Limit
The total installed initial luminaire lumens of all outdoor lighting
shall not exceed the total site lumen limit. The total site
lumen limit shall be determined using either the Parking Space
Method (Table A) or the Hardscape Area Method (Table B).
Only one method shall be used per permit application, and for
sites with existing lighting, existing lighting shall be included
in the calculation of total installed lumens.
The total installed initial luminaire lumens is calculated as the sum
of the initial luminaire lumens for all luminaires.
The allowable lumens are based on the lighting zone and the total hard-
scape area. Referencing Table B, the allowed lumens are 2.5/SF for LZ2.
Multiplying this by the total hardscape square footage gives a value of
250,000 lumens allowed. Because this value is greater than the value
calculated for the site, the project complies. Listed below is an example
on a typical compliance worksheet for the Prescriptive Method.
USER’S GUIDE - Page 12
Page B-12
ORDINANCE TEXT - Page 12
Appendix B: Model Lighting Ordinance