Reuse of Light Fixtures and Mechanical Vents

I am wondering if the reuse of light fixtures and mechanical vents has ever been used towards an ID credit. I understand that these divisions are not counted towards any of the MR credits. However, I have had several jobs that a very large dollar amount and cubic yardage worth of these products have been reused. In all cases the fixtures were all relatively new and meet the current energy standards. In several case the building design was designed around how many fixtures were available for reuse. If these had been thrown away and new ones purchased several dumpster loads extra of waste would have been put in a landfill. Is this even worth attempting?