Lighting Design Calculator
Calculate luminaire quantity automatically or set a fixed quantity. Import IES/LDT photometry for a point-by-point false-colour illuminance map on the selected workplane.
Calculation method
Without a photometry file, the calculator uses the lumen method N = E × A / (F × UF × MF). In fixed-quantity mode it reverses the same relationship to show achieved average illuminance. With IES/LDT loaded, the horizontal workplane is evaluated point by point from the luminaire intensity distribution, mounting height and maintenance factor.
How to use the result
Use the result for preliminary fixture quantity and energy-density checks. Utilization factor should come from photometric data or an appropriate room-index method, while the maintenance factor should reflect the environment, cleaning interval and lumen depreciation assumptions.
Method guide: Lumen Method Lighting Calculation works through the UF/MF equation and shows when to move from average-lux screening to IES/LDT photometry.
Engineering limits
The IES/LDT engine evaluates direct illuminance on the horizontal workplane and adds a simplified diffuse interreflection correction based on room geometry and ceiling, wall and floor reflectances. This makes reflectance inputs affect average lux and uniformity. It is still not a full multi-bounce radiosity, UGR, daylight or emergency-lighting calculation equivalent to RELUX or DIALux.
Before design release
Record the source and revision of every project input used in this calculation, then compare the result with the next practical equipment or conductor size rather than treating the numerical minimum as an automatic selection. Check tolerances, environmental derating, duty cycle, protection settings, installation constraints and manufacturer limits that are outside the simplified model. Where the result feeds another study, carry the same voltage, current, power-factor, fault-level and timing assumptions forward so the design chain remains traceable. Save the governing case and the reason for the final engineering choice. ElectroDesigner is intended to make the calculation path visible; it does not replace the project engineer’s verification, the adopted standard or tested manufacturer data.