Wattage Per Square Meter Warehouse

仓库每平方米瓦数

Recommended Values by Application

These figures assume LED sources at 120–140 lm/W and a maintained illuminance of 150–200 lx on the working plane, per EN 12464-1:2021 for general warehouse storage and handling. If you're dealing with high-bay racking or fine-picking areas, you'll need to bump up the target.

What does this mean in practice? If you're spec'ing a 10,000 m² general warehouse, you're looking at 50–80 kW of connected load. That's a big number for the electrical contractor and the utility bill. Don't just take the low end—check your ceiling height. At 12 m, you'll need higher wattage per square meter because the light has to travel further and you're fighting the inverse square law.

Specification Comparison

Here's how the numbers break down across three quality tiers. The catch is that "premium" doesn't always mean higher wattage—it means you get more useful lumens on the floor for the same or lower power.

Bottom line: if you're still seeing 10 W/m² on a modern LED spec, someone's either using old fixtures or they've got a very high illuminance target. Push back. Ask for the photometric file.

Why Wattage Per Square Meter Warehouse Matters

Let's put numbers to this. A 20,000 m² distribution center running at 8 W/m² pulls 160 kW. At €0.12/kWh, running 16 hours a day, 5 days a week, that's €1,536 per week—€79,872 per year. Drop that to 5 W/m² with better optics and controls, and you're at €49,920. That's a €30,000 annual saving. On a single site.

But it's not just about the energy bill. Wattage per square meter directly affects your cooling load. Every watt of lighting power that ends up as heat (and with LEDs, about 70–80% does) adds to your HVAC burden. In a refrigerated warehouse, that's a double hit: you're paying for the light and then paying again to remove the heat. I've seen facilities where lighting accounts for 15–20% of the total cooling load. That's real money.

There's also the regulatory angle. EN 15193-1:2021 on energy performance of lighting installations sets a maximum allowable lighting energy numeric indicator (LENI) for warehouses. For a typical warehouse, the LENI target is around 10–15 kWh/m² per year. If your wattage per square meter is too high, you'll blow past that limit and fail compliance checks. Procurement teams need to understand that this metric isn't optional—it's baked into building regulations across the EU.

Application Scenarios

Scenario 1: High-bay pallet racking, 12 m ceiling height. You need narrow-beam optics (40–60°) to get light down between the racks. With 150W high-bays at 140 lm/W, spaced 6 m apart, you'll land around 5–6 W/m² for 200 lx maintained. Don't use wide-beam fixtures here—you'll waste 30% of the light on the rack faces. I've seen it happen.

Scenario 2: Cold storage at -20°C. LED drivers hate the cold? Actually, they love it—efficacy improves by 5–10% at low temperatures. But you need to check the driver's minimum starting temperature per IEC 60598-2-24. Expect 6–8 W/m² because you're fighting frost on fixtures and lower reflectance from white freezer walls (typically 50–60% vs. 70–80% in a dry warehouse). Use sealed IP65 or IP66 fixtures.

Scenario 3: Automated storage and retrieval system (AS/RS). Minimal human occupancy means you can drop to 2–4 W/m² at 100 lx. But here's the trick: the AS/RS machines need consistent light for their optical sensors. You can't just turn everything off. Use zoned controls with occupancy sensors that keep a 50 lx background level and boost to 150 lx when a technician enters.

Scenario 4: Manual picking with high SKU density. This is where you need 8–12 W/m². The workers are reading labels, scanning barcodes, and moving fast. EN 12464-1 calls for 300 lx on the picking face. Use linear LED strips mounted on the racking itself—task lighting at the point of work. It's more efficient than trying to light the whole aisle from the ceiling.

Design Guidelines

Here's a rule of thumb I've used on dozens of warehouse jobs: start with 5–7 W/m² for a 10 m ceiling height at 200 lx, then adjust by ±1 W/m² for every 2 m of ceiling height change. So at 8 m, target 4–6 W/m²; at 14 m, target 7–9 W/m². This accounts for the inverse square law and fixture spacing.

Always run a calculation in Dialux or Relux before you commit. The wattage per square meter is a starting point, not a final spec. I've had projects where the initial estimate was 6 W/m² and the final design came in at 4.5 W/m² because we used high-efficacy fixtures with good optics. Conversely, I've seen 8 W/m² estimates blow up to 11 W/m² because the client wanted 500 lx on the floor for some reason.

Don't forget the maintenance factor. EN 12464-1 recommends a maintenance factor of 0.7–0.8 for warehouses, depending on dirt accumulation. If you're in a dusty environment (cement, grain, paper), use 0.7. That means you need to design for 30% more light at installation to hit the maintained illuminance after 3–5 years. That pushes your wattage per square meter up by the same factor.

One more thing: controls. A good occupancy sensor system can cut energy use by 40–60% in low-activity zones. That doesn't change the installed wattage per square meter, but it dramatically changes the actual energy consumption. When you're writing the spec, separate the "installed" number from the "operational" number. Procurement teams often get confused by this.

Key Takeaways