Section
Retrofit & economics
Replacing fluorescent and discharge lighting: what actually changes, what it costs, and how to build a payback case that a finance department will accept.
High bay: why "400 W metal halide equals 150 W LED" is not a specificationWhat wattage-equivalence claims leave out, how depreciated HID output makes the comparison unfair in both directions, why vertical illuminance on rack faces matters more than floor lux, and the operational gains that usually exceed the energy saving.
T8 fluorescent to LED: tube swap versus luminaire replacementThe four retrofit routes for a fluorescent installation, what each does to photometry, safety certification and liability, why a lumen-for-lumen tube swap often lands illuminance in the wrong place, and the costs that never appear in the tube price.
The retrofit measures low: nine causes, in the order worth checkingWhen a completed retrofit fails its lux survey, the fault is as often in the measurement as in the installation. The meter class problem, warm-up drift, reference plane errors, and the design assumptions that quietly did not survive to site.