I'm working on a project that is evaluating some different facade lighting and canopy options. We are in LZ2, so we can't use the facade lighting uplight exemption. We are using the BUG method (unless we can't resolve this without photometrics...).
The lighting designer has proposed a fixture like this: https://brucklighting.com/products/outdoor-cylinder-4in-up-and-down.html on the facade, with a brighter light pointing down for walkway safety lighting and a softer uplight for the facade. There is a roof-level canopy (2 stories above the fixture).
The canopy may be used for PV, in which case we'd have an opaque surface blocking the uplight from the sky and would show it as exempt from the U-2 limit. Another option would be a fritted glass canopy (frit level TBD). My gut feeling says this (at least at a higher frit %) would meet the intent of the credit, as it would block some of the light output and diffuse the light that does get through. If you looked at it from above, probably no different from downlight reflecting off concrete elsewhere on the site. But I'd like to be more sure on it meeting the credit requirement before giving the team the go-ahead.
I guess ultimately my question is - is there any semi-opaque surface we could treat as opaque for the purpose of blocking uplight? A minimum frit % it should meet? Or any review experience with demonstrating that uplight is shielded? Thanks!