Everything about LED efficacy for warehouse projects: what lm/W numbers mean, how to calculate energy savings from efficacy improvements, current benchmarks (120-200+ lm/W), and how to specify efficacy without overpaying.
Efficacy (lumens per watt, lm/W) measures how efficiently a luminaire converts electrical power into visible light. It's the single most important number for calculating warehouse lighting energy costs and ROI. A 150 lm/W fixture produces 50% more light per watt than a 100 lm/W fixture — meaning 33% fewer fixtures or 33% lower electricity bills for the same light output.
Current LED efficacy landscape (2026): 120 lm/W — minimum for new installations (DLC Standard), entry-level commercial grade; 150 lm/W — mainstream premium, sweet spot for ROI on most warehouse projects; 170-180 lm/W — high-performance tier, typically 15-25% price premium over 150 lm/W; 200+ lm/W — cutting-edge (chip-on-board, advanced optics), significant premium, best for facilities with very high energy rates or 24/7 operation.
Each 10 lm/W improvement reduces annual energy cost by approximately 6-7% at constant light output. For a 10,000 m² warehouse operating 6,000 hrs/year at $0.12/kWh: upgrading from 120 to 150 lm/W saves ~$8,500/year. Upgrading from 150 to 180 lm/W saves an additional ~$5,700/year. The ROI depends on the fixture price premium and electricity rates.
Getting lux right is not optional — it's a regulatory requirement under EN 12464-1 (Lighting of Indoor Workplaces), which mandates minimum maintained illuminance levels for every office zone. Undershooting causes eye strain, headaches, and productivity loss. Overshooting wastes energy and causes glare. This guide gives you the exact numbers.
The table below lists maintained illuminance (Ēm) requirements for every common office zone per EN 12464-1. Use these values as the minimum design target — going slightly higher (10–20%) is acceptable to account for future degradation.
| Office Zone | Ēm (Maintained Lux) | Uniformity U₀ | UGR Limit | Ra (CRI) Min | Notes |
|---|---|---|---|---|---|
| 💻 Workstation (Desk) | 500 lx | ≥ 0.6 | < 19 | ≥ 80 | Measured on the task area (desk surface). Writing, typing, reading, data processing. |
| 🤝 Meeting / Conference Room | 500 lx | ≥ 0.6 | < 19 | ≥ 80 | Ensure dimmable for presentations. Consider tunable white for video calls. |
| 🎨 Design Studio / CAD Office | 750 lx | ≥ 0.7 | < 16 | ≥ 90 | Higher visual acuity for detailed technical drawings. Stricter UGR. |
| ☕ Break Room / Pantry | 200–300 lx | ≥ 0.4 | < 22 | ≥ 80 | Relaxation zone — lower illuminance acceptable. Warmer CCT (3000K) preferred. |
| 🚶 Corridor / Circulation | 150–200 lx | ≥ 0.4 | < 25 | ≥ 80 | Floor-level measurement. Emergency egress paths require minimum 0.5 lx backup. |
| 🗄️ Filing / Archive Room | 200–300 lx | ≥ 0.4 | < 22 | ≥ 80 | Vertical illuminance on shelves should be ≥ 150 lx at 0.2 m from floor. |
| 🚻 Reception / Lobby | 300–500 lx | ≥ 0.5 | < 22 | ≥ 80 | Higher end (500 lx) for reception desks where reading and visitor interaction occurs. |
| 🖨️ Print / Copy Area | 300–500 lx | ≥ 0.4 | < 19 | ≥ 80 | 300 lx general + 500 lx at service areas for maintenance tasks. |
| 🔧 Server / Technical Room | 200 lx | ≥ 0.4 | < 25 | ≥ 80 | Primarily for maintenance access. Emergency lighting required. |
Lux is a Goldilocks parameter — too little and people suffer; too much and you waste money while creating glare. Here's what happens at each level for a standard office workstation:
Key takeaway: The 450–550 lx range is the sweet spot for standard offices. Below 300 lx is a health and compliance risk. Above 750 lx wastes energy without meaningful visual improvement — the human eye's perceived brightness follows a logarithmic curve, so doubling lux from 500 to 1,000 only feels ~40% brighter.
Standard workstation illuminance. Uniform distribution across all desks critical.
Task + ambient layered. Desk lamp for focused 750 lx on documents, ambient at 300–500 lx.
High visual acuity for detailed drawings. CRI 90+ mandatory. Stricter UGR < 16.
500 lx general + 1,000 lx on examination areas. Tunable white for circadian support.
Use this table to quickly match your office type to the correct lux level and fixture specification. All values comply with EN 12464-1:2021.
| Office Type | Recommended Lux (Ēm) | CCT | CRI (Ra) | UGR | Suggested Fixture |
|---|---|---|---|---|---|
| Warehouse Profile | Recommended Efficacy | Annual Savings vs 120 lm/W (10k m²) | |||
| Day Shift Only (2,500 hrs/yr) | 130-140 lm/W | $3,500/yr | |||
| Extended Hours (4,000 hrs/yr) | 150-160 lm/W | $8,000/yr | |||
| Two Shifts (6,000 hrs/yr) | 160-180 lm/W | $12,000/yr | |||
| 24/7 Operation (8,760 hrs/yr) | 180-200+ lm/W | $17,500/yr | |||
| Cold Storage (8,760 hrs/yr) | 170-190 lm/W | Extra savings from reduced cooling load |
150 lm/W is the ROI sweet spot for most warehouses with 4,000+ operating hours/year. Below 3,000 hrs/yr: 120-130 lm/W. Above 6,000 hrs/yr or high electricity rates: 170-180 lm/W. Always calculate lifecycle ROI (10-year) using projected electricity rates, not just upfront cost comparison.