Every light in the warehouse is switched on. The electricity bill confirms it. Yet the aisles
still feel gloomy, the lower shelves are in shadow, and your team squints to read labels. It is
frustrating and it slows everyone down. The good news: this is a design problem, not a “buy more
lights” problem — and understanding it saves you from wasting money on fittings that will not
help.
Reason 1: The Wrong Fixture Shape for Aisles
This is the most common cause. Round UFO high bays throw a circular pool of
light — fine for open floors, wrong for narrow aisles. In an aisle, that circular light hits the
tops of the racks and leaves the lower shelves in shadow. Linear high bays
mounted along the aisle push light down the whole corridor and deep into the shelving. Same
energy, completely different result.
Reason 2: You Are Measuring the Floor, Not the Shelves
Most lighting is designed for light on the floor (horizontal lux). But your team
does not read the floor — they read shelf faces. That needs
vertical illuminance, the light landing on the vertical rack. A warehouse can
have a perfectly good floor-lux number and still feel dark where it matters. Always ask about
vertical illuminance on the racks.
Reason 3: Shadows From Tall, Dense Racking
Tall shelves block light from reaching between and below them. The fix is correct fixture
placement along aisles (not across them) and spacing so light pools overlap, removing
the dark bands between rows.
Reason 4: Dirty Fixtures or Old Technology
Dust on lenses can quietly swallow a large share of output in industrial air. And old metal
halide fades badly with age — a 5-year-old lamp may give far less light than when new, even
though it is “on”. Cleaning and upgrading to LED restores what you are missing.
Reason 5: Simply Not Enough Light for the Task
Finally, the space may genuinely be under-lit for the work. Match light levels to the task:
| Zone | Recommended Lux |
|---|---|
| Bulk storage | 150–200 lux |
| Picking aisles | 200–300 lux |
| Packing / QC | 500–750 lux |
Frequently Asked Questions
Why does my warehouse feel dark when the lights are on?
Usually the wrong fixture type for aisles, light measured on the floor instead of the
shelves, shadows from tall racking, dirty or aged fittings, or genuinely too little light.
Are round or linear high bays better for aisles?
Linear high bays along the aisle light the full corridor and lower shelves far better than
round UFO fixtures.
What is vertical illuminance?
The light landing on vertical shelf faces — what workers actually read — which matters more
than floor lux in storage aisles.
Do I need more lights or better placement?
Often better fixture type and placement, not more fittings — which also avoids wasting money
and energy.
Reway fixes dark warehouses with aisle-optimised LINEBAY and ULTRABAY high bays and a free
lighting layout. Get a warehouse lighting fix →
