Formula variables
- Area is the floor or task area in square metres.
- Target lux is the desired maintained illuminance.
- Light loss factor is entered as a decimal from greater than zero to 1.
- Efficacy translates estimated lumens to preliminary LED watts.
Assumptions
- Area is entered in square metres.
- Target lux is the maintained illuminance planning value.
- Light loss factor accounts for maintenance, dirt, ageing, and layout losses as a simplified single factor.
- This does not replace lighting design, photometric layout, emergency-lighting review, or project specifications.
Examples
Electrical room planning. A 40 m2 room at 500 lux with a 0.8 light loss factor needs about 25,000 lumens before fixture selection.
Early load estimate. At 130 lm/W, that same 25,000 lumen target estimates about 192.3 W before layout and fixture selection.