Forum discussion
NC-v4 SSc6: Light pollution reduction
Anyone have experience documenting an uplight light fixture with a permanent structure above for “partial lumens above horizontal” calculation, please let me know
do you recall what types of calc or how intricate the details/calcs were to support the special circumstances on the form?
LEEDuser is supported by our premium members, not by advertisers.
Go premium forTo post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.
Is existing lighting required to be included in the calculations? What are the exceptions?
Does athletic field lighting need to be included in this credit?
What’s the difference between the Project Boundary and the Lighting Boundary?
Bill Swanson
Sr. Electrical EngineerIntegrated Design Solutions
LEEDuser Expert
731 thumbs up
February 18, 2021 - 3:17 pm
I'd draw a section showing the light and the structure above. Show what angle the structure blocks light. Describe it. The fixture is aimed straight up. 100% of light is blocked on the building side of the fixture. The structure blocks light between 0-30% on the other side.
Get the IES file into an analizer that will show you how many lumens are in each 10 degree zone. "Lumens Per Zone" on page 2.
https://www.visual-3d.com/tools/photometricviewer/default.aspx?sessionid...
Total lumen output of the fixture is: 7204 lumens.
Half are blocked on the building side: 3602 lumens shielded
Structure blocks 0-30 degree range: 29.3% of the remaining 3602 lumens = 1055 lumens shielded.
7204 - 3602 - 1055 = 2547 lumens of uplight for this fixture.
Something like this will be enough for documentation. The more complicated the angles are, the more complicated the math. The aiming of the fixture is the 0 degree angle of the IES file.
Jack Ma
February 18, 2021 - 3:54 pm
Bill,
Thanks for the input. I was thinking of showing something similar. I used photometric toolbox and obtained a LCS graph and overlayed it to the section.
Is this what you meant by your description? Did you get 29.3% for a specific fixture you're referring to?
In my screenshot example linked below: I take it that I am taking the uplight lumens from (90 degrees to ~110 degrees) divided by 2 (since the building side is completely blocked)
https://drive.google.com/file/d/1wEntPRIg_s2fmRje2F_DczzhaGc25flk/view?usp=sharing
Please let me know if my interpretation is correct. Thanks for your help!