Hi Bill,
Do you know how to account for exterior lighting that does not have published BUG ratings? We are trying to get this information from the architect but he says that most of the exterior lighting does not have published BUG ratings and that "recessed down lights do not have BUG ratings." He also says that since some of the lights are wall mounted, they do not have backlight and therefore the rating would be B0. Lastly, he says that "all other luminaires are fully shielded, full cut-off fixtures. Per the IES Standard TM-15 for BUG ratings, as these fixtures are pointed down, their BUG ratings would all be B0-U0-G0."
The credit language makes it sound like all lighting types will have an associated BUG rating whether they are wall-mounted or not. Can you provide any clarification on this? I am not sure how to respond since I have not worked much on this credit under v4.
Thank you.
Joyce Kelly
Architect - Cx Provider - Green Building SpecialistGLHN Architects & Engineers
26 thumbs up
September 22, 2017 - 1:10 pm
We recently ran into full cut-off LED parking lot fixtures spaced far apart with Glare ratings of 3. Suffice to say, they did not comply. Wall- mounted lighting may well have high glare or uplight.
Every fixture our office specs has a BUG rating available but residential or low grade fixtures may not.
Jill Perry, PE
ConsultantJill Perry, LLC
LEEDuser Expert
440 thumbs up
November 1, 2017 - 10:25 am
The BUG rating method is not for everyone. It is a quick, simple way for sites that are only using fixtures that have a BUG rating or one that can easily be calculated to comply. That is why there are the calculation options.
I agree with everything your architect is telling you but they might be missing a nuisance when talking about "as these fixtures are pointed down." This seems to imply every lumen leaving the fixture goes in a straight vertical direction to the ground. I'm pretty sure only lasers do this. ;) This is why the BUG rating method was developed, to make it easier for people who don't know how or don't want to take the time to evaluate every luminaire's candela curve.
Wall mounted fixtures can and will have B, U, and G ratings greater than 0. If they're mounted to a flat wall that goes straight down to the ground (instead of on the end of an overhang say) then the lumens responsible for the "B" portion of the rating will be blocked by the wall and I would state this in your credit documentation.
Certain lighting calculation software will calculate BUG ratings from IES files (AGi32 is one but I know there are others). However, not all fixtures have IES files either. Though the credit language might imply all fixtures come with a BUG rating, it is a voluntary program for manufacturers. Not all of them have the resources or a big enough need to comply.
Bill Swanson
Sr. Electrical EngineerIntegrated Design Solutions
LEEDuser Expert
734 thumbs up
November 1, 2017 - 10:42 am
The credit language ignores the backlight rating of wall mounted fixtures.