# Warehouse Lighting Design: High-Bay LEDs, Rack Aisles and Daylight

> Warehouse lighting design puts light where the work is: down narrow rack aisles, onto pick faces and rack labels, and evenly across open floor, without glare for drivers looking up. Uniformity, beam distribution and controls matter more than a high average lux, and daylight from roof sheets saves electric lighting only if the heat it brings in is managed.

## Average lux is the wrong headline

Warehouse lighting is usually bought on two numbers: a target lux level and a
fitting count. A lighting layout is produced on an empty floor plan, the average
lux comes out above the target, and the job is signed off.

Then the racking goes in. Aisles turn out dim at the pick faces, labels at the
upper levels are hard to read, drivers squint into bright fittings when they look
up, and the lights burn all day in aisles nobody visits. **A high average lux
across the floor says very little about whether people can see what they are
doing.** As with offices, [lux alone is not enough](/blog/office-lighting-why-lux-alone-is-not-enough),
and in a warehouse the gap is wider, because the work happens on vertical rack
faces at height, often from a moving vehicle.

For an operations head the costs are concrete: picking errors, slower picking,
forklift contact with racking, an energy bill for lighting empty aisles, and
failed fittings nobody can reach without clearing an aisle.

## The racking decides the lighting layout

The single most important input to warehouse lighting is the racking layout.
Luminaires in a racked area belong above the aisles, aligned with them, not on a
uniform grid across the roof. When racking is moved or added after the lighting
is fixed, fittings end up above rack tops, where they light pallets nobody needs
to see and leave the aisles dark.

| Area | What matters most | Typical approach |
| --- | --- | --- |
| Open bulk storage | Even light across the floor, no dark patches between fittings | High-bay luminaires on a regular layout with wide distribution |
| Narrow rack aisles | Light on the vertical rack faces, top to bottom | Aisle optics with a narrow, elongated beam along the aisle |
| Pick faces | Reading labels and barcodes, colour where it matters | Vertical illuminance checked at label heights |
| Loading docks | Trailer interiors, transition from daylight | Dock lights into the trailer, higher interior levels near doors |
| Packing and dispatch | Close visual work at benches | Task-level lighting chosen for the activity |
| Mezzanines | Lower mounting height, glare at eye level | Lower-output fittings, shielding |

Standards such as **IS 3646 (Part 1)** and **EN 12464-1** tabulate recommended
lighting by task and area, including illuminance, uniformity and glare limits.
The lighting designer selects the values for each zone; what [lux level](/glossary/lux-level)
means, and how it is measured, is explained separately.

## Uniformity and glare matter more than brightness

**Uniformity** is the ratio between the lowest and the average illuminance across
an area. Eyes adapt to the general level; what causes trouble is a dark patch in
a bright space, where a pallet, a person or a spill disappears. A layout that
hits a high average with poor uniformity can be harder to work in than one with a
lower, even level.

**Glare** is the other half. Someone walking rarely looks at a high-bay fitting.
A forklift or reach truck driver does, constantly, when placing or retrieving
loads at upper levels. An unshielded, high-output source in that line of sight
dazzles exactly when precision matters. Luminaire choice, shielding, mounting
height and position relative to the aisle direction reduce it, and the
standards include glare limits the designer checks.

**Colour rendering** matters where labels are colour-coded or goods are
inspected; the requirement varies by activity.

**Flicker** is easy to overlook. Poor-quality LED drivers can produce flicker
that is barely visible but tiring over a shift, and near rotating machinery it
can create a stroboscopic effect that makes moving parts appear slow or still.
Driver quality belongs in the specification, not only the luminaire's output.

## Mounting height and beam: a fitting is more than its wattage

High-bay luminaires are often compared on wattage and lumen output alone. Two
fittings with the same output can perform very differently in the same building,
because what decides the result is how the light is distributed from the
mounting height to the working plane.

A wide beam from a high roof spreads light across open floor and overlaps
evenly between fittings. The same beam over a narrow aisle between tall racks
throws most of its light onto the rack tops and the upper pallets, and little
reaches the lower rack faces. A narrow or elongated beam aligned with the aisle
does the opposite. Mounting height also changes with the roof profile: in a
pitched portal frame shed the fittings near the eaves sit lower than those near
the ridge, and a layout that ignores this gives bright and dim bands.

That is why a lighting design should come with a calculation for the actual
roof, racking and fitting, showing horizontal and vertical light in the aisles,
rather than a rule-of-thumb fitting count for the floor area.

## Daylight: skylights bring heat as well as light

Translucent roof sheets are a common way to bring daylight into a shed, and in
daytime operation they can reduce the need for electric light.
[Polycarbonate skylight sheets](/materials/polycarbonate-skylight-sheet) and FRP
sheets differ in light transmission, diffusion, ageing and fire behaviour.

The trade-off is heat. A skylight admits solar heat along with light, and on a
metal roof in an Indian summer that raises the temperature under the roof in a
naturally ventilated shed, or adds to cooling load in a conditioned one. More
skylight area is not automatically better. The useful questions are how much
area, how evenly it is distributed, whether the sheet diffuses light to avoid
hot spots and harsh shadows, and whether the electric lighting actually dims when
daylight is sufficient. Without daylight controls, skylights add heat and save
nothing.

Translucent sheets are also fragile and are a frequent leak point at laps; both
need detailing, and no one should walk on them.

## Controls: most aisles are empty most of the time

LED high-bay luminaires switch and dim instantly, which older high-intensity
discharge lamps could not do without a warm-up delay. That makes controls
practical in a way they were not before.

- **Occupancy sensing** per aisle lets lighting rise when a vehicle or person
  enters and fall back when the aisle is empty.
- **Daylight sensing** dims fittings in zones under skylights or near wall
  glazing when daylight is enough.
- **Zoning and scheduling** match lighting to shifts and to areas that are not
  in use.

**ECBC 2017** sets energy efficiency provisions for lighting and controls in
buildings within its scope, and lighting power density is the related measure.
Sensor positions and time delays need commissioning against real traffic, or
lights switch off around a driver.

## Maintenance at height

High-bay fittings are typically mounted high above the floor, and every one of
them will need attention at some point. Usually that means a mobile elevating
work platform, which needs floor space and an aisle wide enough beneath the
fitting. Check maintenance access against the racking layout at design, choose
fittings with long rated life and replaceable drivers, and specify an
[IP rating](/glossary/ip-rating) suited to dust and humidity in the building.

## Common mistakes

- **Designing lighting on an empty floor plan** before the racking is fixed.
- **Judging the design on average lux** without checking uniformity and vertical
  light on rack faces.
- **Wide-beam fittings over narrow aisles**, lighting rack tops instead of faces.
- **Skylights without daylight controls**, adding heat with no saving.
- **No occupancy sensing in aisles** that are empty most of the day.
- **Fittings placed where no platform can reach them.**

## What to ask your lighting designer

- Which racking layout was the design based on, and is it final?
- What illuminance, uniformity and glare limits were used for each area, from
  which standard?
- How is vertical illuminance on rack faces checked?
- How will skylights and electric lighting work together?
- Which controls are proposed, and how will they be commissioned?
- How will each fitting be reached for maintenance?

## Standards referenced

Recommendations for working interiors in **IS 3646 (Part 1)**; lighting of
indoor work places in **EN 12464-1**; lighting and controls in **ECBC 2017**;
lighting and natural ventilation in **NBC 2016, Part 8**. Illuminance, uniformity,
glare limits and controls for a specific warehouse must be established by the
project's lighting designer and services engineer; nothing on this page replaces
that design.

## Frequently asked questions

### How much light does a warehouse need?

It depends on the task. Standards such as IS 3646 (Part 1) and EN 12464-1 tabulate recommended illuminance by activity, so bulk storage, picking, packing and dispatch areas differ, and they also set expectations for uniformity and glare. The lighting designer selects the values for each area. A single figure applied across the whole building usually over-lights some areas and under-lights the ones that matter.

### Why do some aisles look dark even though the lux reading is fine?

Because lux is usually measured on the floor, while the work in a racked aisle is on the vertical faces of the racks: labels, barcodes and pallets at height. A luminaire with a wide beam over a narrow aisle lights the rack tops and the floor but leaves the faces dim. Aisle lighting needs optics chosen for the aisle width and rack height, checked on vertical surfaces.

### Do warehouse skylights save energy?

They can reduce electric lighting during the day, but translucent roof sheets also admit solar heat, which in a non-air-conditioned shed raises the temperature under the roof and in a conditioned one adds cooling load. The saving depends on the skylight area, how the light is diffused and whether lighting controls actually dim when daylight is available. The trade-off should be assessed rather than assumed.

### Are occupancy sensors worth fitting in a warehouse?

In racked aisles they often are, because most aisles are empty most of the time. LED luminaires can dim or switch instantly without the warm-up delay older high-intensity discharge lamps had, so aisle lighting can respond to a forklift entering. Sensor placement and timing must suit the traffic, or lights switch off around drivers. ECBC 2017 sets a framework for lighting controls.

### What causes glare for forklift drivers?

Drivers spend much of their time looking up at the upper levels of racking, so luminaires that would be out of sight for someone walking come directly into their field of view. Bright, unshielded high-bay sources at the wrong angle are the usual cause. Luminaire choice, shielding and position relative to aisle direction reduce it, and standards include glare limits the designer checks against.

### How are high-bay lights maintained?

Usually from a mobile elevating work platform, which needs a clear route and floor space beneath each fitting. A luminaire above a rack top, or above an aisle too narrow for the platform, may be impossible to reach without moving stock. Maintenance access should be checked against the racking layout at design, and fittings chosen with long life and accessible drivers.

## Sources

- [IS 3646 (Part 1)](https://standards.bis.gov.in/website/published-standards/department-wise) — Interior illumination - general requirements and recommendations for working interiors
- [EN 12464-1](https://standards.cencenelec.eu/ords/f?p=CEN:105) — Light and lighting - lighting of work places - indoor work places
- [ECBC 2017](https://beeindia.gov.in/) — Lighting and controls
- [NBC 2016, Part 8](https://www.bis.gov.in/standards/national-building-code/) — Building services - lighting and natural ventilation

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Source: https://hagerstone.com/blog/warehouse-lighting-high-bay-and-daylight