MODEL LIGHTING ORDINANCE - USER ’ S GUIDE MODEL LIGHTING ORDINANCE -
TEXT
IV . NON-RESIDENTIAL LIGHTING ( cont .) - User ’ s Guide
LIMITS TO OFFSITE IMPACTS ( cont .)
The second step in the Performance Method is to determine if the proposed luminaires are producing off site impacts such as glare , sky glow and light trespass . One may either use Option A which are the Maximum Allowable BUG Ratings in Table C , or Option B through computer lighting calculations show compliance with Maximum Vertical Illuminance at any point in the plane of the property line in Table F . Option B will be required for all non-residential luminaires that A ) do not have BUG ratings , or B ) exceed the BUG ratings , C ) are not fully shielded , or D ) have adjustable mountings .
For the performance method , Option B ( 2 ) requires photometric calculations for the site perimeter , to a height of no less than 33 feet ( 10 meters ) above the tallest luminaire . Vertical illuminances at eye height ( 5 feet above grade ) will give values that can be used to verify compliance by comparing actual site conditions to the photometric plan submitted during review . Note that the MLO specifies ' total initial luminaire lumens ' as a measurement in addition to footcandles / lux . The footcandle ( lux ) is equal to one lumen per square meter . Lux is the metric unit and is equal to one lumen per square meter .
IV . NON-RESIDENTIAL LIGHTING ( cont .) - Ordinance Text PERFORMANCE METHOD
2 . Limits to Off Site Impacts All luminaires shall be rated and installed using either Option A or Option B . Only one option may be used per permit application .
Option A : All luminaires shall be rated and installed according to Table C .
Option B : The entire outdoor lighting design shall be analyzed using industry standard lighting software including interreflections in the following manner :
1 ) Input data shall describe the lighting system including luminaire locations , mounting heights , aiming directions , and employing photometric data tested in accordance with IES guidelines . Buildings or other physical objects on the site within three object heights of the property line must be included in the calculations .
2 ) Analysis shall utilize an enclosure comprised of calculation planes with zero reflectance values around the perimeter of the site . The top of the enclosure shall be no less than 33 feet ( 10 meters ) above the tallest luminaire . Calculations shall include total lumens upon the inside surfaces of the box top and vertical sides and maximum vertical illuminance ( footcandles and / or lux ) on the sides of the enclosure .
The design complies if :
a ) The total lumens on the inside surfaces of the virtual enclosure are less than 15 % of the total site lumen limit ; and
b ) The maximum vertical illuminance on any vertical surface is less than the allowed maximum illuminance per Table F .
USER ’ S GUIDE - Page17 ORDINANCE TEXT - Page 17
Appendix B : Model Lighting Ordianance Page B-17