A 1,850 m² store in Brasilia replaced burnt luminaires like-for-like. I mapped the real illuminance of each sales zone and redesigned the retrofit: the same light level, 34% less installed power and one circuit per department.
It arrived as a catalogue quote: pull out the 112 fluorescent fittings and fill the store with round panels. The real problem sat elsewhere. Eight circuits mixed the shop front, the aisles and the warehouse, so the manager lit the whole store to open three checkouts. And the board had no protective conductor and no residual current device on the garden side.
| Zone | Measured illuminance | Standard reference | Power before | Power as designed |
|---|---|---|---|---|
| Shop front | 310 lx | 500 lx | 1,840 W | 1,120 W |
| Aisles | 240 lx | 300 lx | 2,560 W | 1,480 W |
| Checkouts | 420 lx | 500 lx | 640 W | 390 W |
| Warehouse and dock | 110 lx | 200 lx | 1,180 W | 760 W |
With the numbers on the table the job turned small in one place and large in another: 28 fittings were already above the NBR ISO/CIE 8995-1 reference and stayed where they were; circuits were split by department with independent switching and three new RCDs; and the warehouse got occupancy control in the racking aisles. Lighting power fell from 6.2 kW to 4.1 kW with no zone below the required level.
A rule of thumb I did not follow: replace it all. A good retrofit does only what the metering tells you to do, not one fitting more.
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