Lighting power density W/m² = total installed power / area, the average efficiency is lm/W = total luminous flux / total power This is determined by using the following: For example, 900 W and 100 m² = 9 W/m²; 120,000 lm = ≈ 133 lm/W. A low W/m² indicates an efficient installation with sufficient illumination.
Power density = P_total / A · Efficiency = Φ_total / P_total
Example calculation: 900 W installed power, 100 m² → 9 W/m²; 120,000 lm with average efficiency ≈ 133 lm/W (efficient LED installation).
Lighting Power Density (W/m²)
Calculate the power density (W/m²) and, if desired, the average efficiency (lm/W) by dividing the installed lighting power by the area.
Power density
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Average efficiency
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Notes: Power density = total power / area (W/m²) · Efficiency = total lumens / total power (lm/W). Low W/m² indicates sufficient illumination and efficient installation. The binding limit varies according to the standard/project (EN 15193 — LENI); modern LED efficiency is typically above 100 lm/W.
How is it calculated?
- Enter the total installed lighting power (W).
- Enter the area (m²).
- (Optional) Enter the total luminous flux (lumens) and press Calculate.
Frequently Asked Questions
What is lighting power density?
It is the installed lighting power per unit area (W/m²); it is an indicator of energy efficiency.
What is a good W/m² value?
The limiting factor varies according to the standard and project (EN 15193 — LENI). Achieving the same illumination level with lower W/m² is more efficient; modern LEDs make this easier.
What does the activity (lm/W) indicate?
The luminous flux produced per watt consumed; a higher lm/W indicates a more efficient luminaire (modern LEDs typically produce over 100 lm/W).
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