Illuminance Standards for Commercial Spaces: Lux Levels, Uniformity & UGR by Space Type

Every commercial lighting project starts with a number: how many lux on the task, the merchandise, or the floor. It is also the number most often quoted without its three companions — uniformity, glare and colour — which is why two installations with the same lux target can feel completely different. This guide gives the reference values by space type, explains the parameters that travel with them, and shows how to turn a lux target into a fixture count.

What Lux Measures, and What the Number Hides

Illuminance (E, in lux = lumens per square metre) is the light arriving at a surface. It is not a property of a fixture: the same luminaire gives a different lux value at every mounting height and beam angle. Photometric quantities you will see on a spec sheet are different things:

• Lumen (lm) — total light output of the fixture, measured in an integrating sphere.
• Candela (cd) — intensity in one direction; the basis of every beam angle and illuminance calculation.
• Lux (lx) — candela falling on a square metre: what a light meter reads on the floor or on the product.
• Luminance (cd/m²) — how bright a surface looks; the quantity your eye and a camera actually respond to.

A single lux figure says nothing about uniformity (is the floor evenly lit or striped with pools?), glare (can people work without shielding their eyes?), vertical illuminance (does the merchandise or the face of a shelf receive light?) or colour quality (does the product look the way it looks in daylight?). Every credible standard therefore specifies illuminance together with those companions.

Where the Numbers Come From: EN 12464-1 and IES Recommended Practice

Two reference systems cover almost every commercial project:

• EN 12464-1 ("Light and lighting — Lighting of work places — Part 1: Indoor work places") is the European standard, adopted as a national standard across the EU and UK (BS EN 12464-1) and widely written into specifications worldwide. It is the most detail-rich source for task-by-task values: maintained illuminance (Ēm), UGR limit, uniformity (U_o) and colour rendering (R_a) in one table per activity. EN 12464-2 covers outdoor workplaces.
• IES Recommended Practice (RP-1 for offices, RP-2 for retail, RP-30 for museums and similar) is the North American reference. It is recommended practice rather than law, but it becomes contractually binding the moment an owner, specifier or energy-code compliance path names it — which is the usual case in the US and Canada.

The two systems agree more than they differ: an office ends up around 300–500 lx either way. What differs is presentation — EN 12464-1 gives one maintained value per task, while IES practice gives ranges with tiers by task contrast and use level.

Lux Levels by Space Type

The table below collects the values we see specified most often for commercial interiors, following EN 12464-1:2021. Treat it as a scoping reference: for a tender, confirm the exact row for your task in the current edition of the standard, because the 2021 revision tightened several values and added a "modified illuminance" step for demanding visual conditions.

Space / task	Maintained illuminance Ēm	UGR limit	Uniformity Uo	Ra
Office — writing, reading, typing, data processing	500 lx	≤19	≥0.60	≥80
Office — CAD workstation, conference table	500 lx	≤19	≥0.60	≥80
Office — filing, copying, circulation	300 lx	≤19	≥0.40	≥80
Reception, lobby, waiting area	300 lx	≤22	≥0.40	≥80
Corridors, internal circulation	100 lx	≤25	≥0.40	≥40
Stairs, escalators	150 lx	≤25	≥0.40	≥40
Retail — sales area	300 lx	≤22	≥0.40	≥80
Retail — cash desk, wrapping	500 lx	≤19	≥0.60	≥80
Hospitality — restaurant, canteen	200 lx	≤22	≥0.40	≥80
Industrial — rough work, storage	200 lx	≤25	≥0.40	≥80
Industrial — medium mechanical work	300–500 lx	≤25	≥0.60	≥80
Industrial — precision work, inspection	750–1000 lx	≤19	≥0.70	≥80
Museum — conservation-limited exhibit	50–200 lx	≤19	≥0.40	≥90

Retail deserves a comment because the horizontal number undersells the job. A 300 lx sales area describes the walking plane; what sells is vertical illuminance on the merchandise — commonly specified around 300–500 lx on display walls for exclusive retail, higher where merchandise must read flat and uniform. That vertical layer is created by accent fixtures aimed at the product, not by raising the ambient level. See our retail store lighting design guide for the layer-by-layer approach.

The Three Numbers That Travel With a Lux Target

1. Uniformity (U_o = E_min / Ēm). A room can average 500 lx and still be unusable if the minimum is 80 lx. Uniformity is the ratio of minimum to average over the task area, and it is the parameter behind most "the lighting looks patchy" complaints. Offices and precision work typically require ≥0.60; other areas ≥0.40.

2. The immediate surrounding area. EN 12464-1 requires a band of at least 0.5 m around the task area, at an illuminance one step down from the task but never below it: for a 500 lx task, at least 300 lx; for 300 lx, at least 200 lx; for 200 lx, at least 150 lx. Uniformity there must be ≥0.40. This is what prevents the "island of light in a dark room" that causes constant adaptation strain.

3. Background and vertical surfaces. Walls and ceiling must receive at least one third of the immediate-surrounding illuminance, with U_o ≥0.10 — for offices, commonly specified as about 150 lx on walls, 100 lx on the ceiling, plus a cylindrical illuminance of about 150 lx so faces and vertical surfaces are modelled rather than flat. A dark ceiling above a bright desk is a standards failure, not a design choice.

Glare: UGR in One Paragraph

UGR (Unified Glare Rating) runs from 10 (imperceptible) to 30 (intolerable) in steps of 3: 10, 13, 16, 19, 22, 25, 28. Offices and cash desks sit at ≤19; retail sales areas at ≤22; circulation and heavy industrial at ≤25; below 16 only where screens, precision inspection or long concentration demand it. UGR is a room metric, not a fixture label: it depends on the luminaire luminance, its position relative to the observer and the room surfaces, which is why the standard is evaluated with the UGR table method in a lighting calculation rather than read off a datasheet. The practical levers are recessed or deeply set optics, anti-glare honeycomb or louvre accessories, lower output per head with more heads, and aiming that keeps bright apertures out of the normal line of sight. Our anti-glare downlight notes cover the fixture-side measures.

Museum and Gallery: When Conservation Sets the Lux

In museums the illuminance is chosen by the conservator, not the lighting designer, because light damage is cumulative and irreversible. The convention in use across most institutions, based on material sensitivity:

Sensitivity	Typical illuminance	Materials
High	~50 lx	Textiles, costumes, tapestries, watercolours, prints and drawings, manuscripts, photographs, silk and unstable dyes
Medium	~150–200 lx	Oil and tempera paintings, wood, leather, parchment, some plastics
Low	200–300 lx	Stone, metals, ceramics, glass, minerals — effectively unlimited for conservation

Two further constraints come with the lux level. First, an annual exposure budget in lux·hours, applying the reciprocity rule (50 lx for 300 hours equals 150 lx for 100 hours): CIE 157:2004 discusses an order of magnitude around 15,000 lx·h per year for high-sensitivity objects, while ICOM guidance is more conservative, in the region of 12,500 lx·h (roughly 250 hours at 50 lx) — with high-sensitivity objects returned to dark storage once the budget is spent. Second, UV control: UV content below 75 µW/lm, with modern practice filtering sensitive displays to about 5–10 µW/lm. LEDs are far ahead of the halogen they replaced here, but "low UV" is still a specification, not an assumption. For luminaire selection under these constraints, see our museum and gallery track lighting guide.

From a Lux Target to a Fixture Count

The lumen method is still the fastest sanity check on any layout:

N = (Ēm × A) / (Φ × UF × MF)

• N — number of luminaires
• Ēm — target maintained illuminance in lux
• A — area in m²
• Φ — luminous flux per luminaire in lumens
• UF — utilisation factor: how much of the flux reaches the working plane, from room geometry and surface reflectances
• MF — maintenance factor, typically 0.80 for clean interiors, 0.70 or lower where dust, grease or vibration are present

Worked example — a 120 m² retail sales area at 300 lx using 30W COB track heads of 3,000 lm, UF 0.70, MF 0.80:

N = (300 × 120) / (3000 × 0.70 × 0.80) = 36,000 / 1,680 ≈ 22 heads, before the accent layer aimed at displays is added. That last clause matters: the lumen method sizes the ambient layer only. Track lighting in retail is usually two layers — ambient heads on wide beams, accent heads on narrow beams at higher output — and the accent layer is sized by vertical illuminance on the merchandise, not by floor lux.

If you want to move faster on scoping numbers, our free lighting calculators do the two calculations above — beam coverage and average illuminance from beam angle and mounting height, and fixture count from a target lux level — and state every formula and assumption used.

Beam Angle, Mounting Height, and the Question That Cannot Be Answered

"How much lux does this 30W track light give?" has no answer without two more numbers. For a point source, illuminance falls with the square of distance:

E = I / h²  (I = intensity in candela toward the surface, h = distance in metres)

Doubling the mounting height quarters the illuminance. Beam geometry follows the same logic — the lit diameter at the target plane is 2 × h × tan(θ/2) for a beam angle θ: a 24° head at 3 m covers a spot of about 1.28 m. This is why the same fixture can be "too dim" on a 4 m ceiling and "too harsh" on a 2.5 m ceiling, and why a beam-angle and mounting-height pair belongs in every specification. Two heads on 24° at 3 m do not light the same area as one head on 60° at 3 m, even at identical lumens.

Five Specification Mistakes We See Repeatedly

1. One lux number for the whole building. Corridors at 500 lx waste energy and flatten the space; task areas at 150 lx fail the standard. Differentiate by task.
2. No uniformity or glare clause. Illuminance alone lets a supplier meet the number with a handful of high-output heads, producing pools of light and disabling glare.
3. Initial lumens treated as maintained lux. Ignoring the maintenance factor means the installation reads 300 lx on day one and 240 lx after two years of dust and depreciation.
4. Ambient-only retail design. Meeting the 300 lx floor target while leaving shelves and mannequins unlit — vertical illuminance is the selling layer.
5. Accepting "lux at 1 m" claims. Centre-beam lux at one metre is a marketing figure for flashlights, not a design input. Ask for lumen output, beam angle, CRI/R9 and the IES file if a calculation is required.

Fixtures That Meet These Targets

Three indoor heads from our range that carry the parameters these standards care about — documented colour rendering, a five-year warranty and the beam control to hit a target area:

• DALI dimmable 40W zoomable museum track light — 2700–6000K, Ra 90, with the adjustment range curators want when the lux limit is fixed
• CCT adjustable 30W track light — 2700–6000K in one head, Ra 90, for fit-outs that are tuned on site
• 30W focus COB track light — DALI dimmable, Ra 90, for the accent layer in retail and galleries

Sources & Verification

This guide references EN 12464-1:2021 (indoor workplaces: maintained illuminance, UGR limits, uniformity, colour rendering) and EN 12464-2 (outdoor workplaces); IES RP-1 and IES RP-2 (office and retail recommended practice in North America); CIE 157:2004 and ICOM museum lighting guidance (sensitivity classes and exposure budgets); and CIE 13.3 for colour rendering. Table values are the market-common figures for the named tasks; project-level values must be taken from the current edition of the applicable standard, and a calculation or measurement should confirm the installed result. Uniformity, UGR and exposure values are quoted as ranges because the standards express several of them as a function of the task, the room and the observer position.

Planning a store, office or exhibition with a lux target already set? Send us the space type, dimensions, mounting height and target illuminance — we will shortlist track and downlight options with the lumen output, beam angle, CRI and glare control that meet it, and confirm the fixture count with you. Talk to our team.