HVAC in lighting

[Mr Zapp]

While inspecting a building for an LED retrofit we found lighting fixtures that also perform ductwork functions. I have never seen this before. The fixtures predictably are very dusty. Some have ductwork attached and some just vent into the ceiling for return air. Would this be a code issue to leave them like this or should they be separated from the lights while we are doing the project? I could not find anything in the code book prohibit ing it, but I think it is a crazy thing to do.

 

[Electromatic]

I've definitely seen options for fixtures to have them as part of the return air--even newer LED troffers--and seen a few installed that way. I don't recall seeing any serving as supply air grilles but wouldn't doubt that that's a thing. I can't really speak to HVAC codes. I suppose if the fixture is listed for that use, the NEC would be okay with it. Obviously if the return air isn't ducted, then you're dealing with a plenum space above the fixtures and wiring methods would need to follow those rules.

 

[GoldDigger]

This was done specifically in some commercial environments so that the energy lost in the fixture can be used to help heat the building. Very likely there are dampers in the system that allow that air to be vented outside when it is cooling that is needed.
This arrangement lets the generated heat be used wherever needed, not just in the best lit areas.
Modern LED fixtures reduce the amount of "free" heat available to the point where the building's controlled heat source may be inadequate.
Stories are told about office buildings with winter temperature problems which were found not to actually have a furnace or heat pump.

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