Forum discussion
CS-v4 SSc6: Light pollution reduction
Hi all,
My project has some lighting fixtures exceeding the BUG rating limit in LZ 3, but these lightings are concealed in steps (See the image attached https://www.dropbox.com/s/22z0zgfahaonbsu/Lighting%20concealed.jpg?dl=0). In this case, BUG rating of some fixtures do not comply with the limit, but the exterior pavement plays as a lighting shield. How can I prepare a documentation for these lighting fixtures?
Please help.
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Bill Swanson
Sr. Electrical EngineerIntegrated Design Solutions
LEEDuser Expert
734 thumbs up
May 23, 2018 - 4:43 pm
This is one of the limitations of the BUG rating system. Surrounding structures are ignored.
Draw a cross section of the steps with the lights. Make it obvious what are solid structures. If you can show that zero light is emitted above 90 degrees then explain that you are applying a U0 to this fixture because of shielding from structure.
But, if it's not blocking all light above 90 degrees, how do you calculate the lumen value that is uplight? That would be extremely difficult to convert into a BUG rating. It would be similarly difficult trying to recalculate the glare rating.
It is possible if you dissect the IES file and get lumen totals at each 10 degree angle of output. Chart which angles are blocked and which are not. It would be messy and I'm sure the Reviewer wouldn't know how to verify if your numbers are right or wrong. I don't know if they would even accept it.