EN 12464-1 — Lighting of indoor work places

What is EN 12464-1?

The European standard EN 12464-1:2021 (formerly EN 12464-1:2011), entitled "Light and lighting — Lighting of work places — Part 1: Indoor work places", defines the minimum requirements for artificial lighting of indoor spaces where people work.

It covers the majority of room types: offices, meeting rooms, entrance halls, corridors, schools, hospitals, retail spaces, professional kitchens, workshops, laboratories, warehouses, covered car parks, etc. It applies in all countries of the European Union, in Switzerland, the United Kingdom, Norway, and generally wherever European standards are recognised.

Why this standard exists

Lighting unsuited to the work causes:

• Visual fatigue — red eyes, headaches, blurred vision at the end of the day
• Errors and accidents — misreading, imprecise handling, falls
• Productivity loss — longer task times, degraded quality
• Musculoskeletal disorders — compensatory postures to see better
• Psychological impact — mood, concentration, stress

EN 12464-1 sets a minimum baseline the employer must guarantee. Compliance is often required by labour inspectorates and insurers.

The 4 key parameters

1. Maintained average illuminance (Ēm)

It is the value measured on the work plane (generally 0.85 m above the floor for an office), expressed in lux (lx). "Maintained" means that this value must be guaranteed after ageing of the lamps and after soiling of the luminaires — a maintenance factor is applied (typically 0,8 for modern LEDs).

2. Uniformity (U0)

Ratio between the minimum and average illuminance over the task area. Typically U0 ≥ 0,60 for the main task area, U0 ≥ 0,40 for the immediate surrounding area (1 m around the task area), U0 ≥ 0,10 for the rest of the room.

3. Glare limitation (UGR)

UGR (Unified Glare Rating), rated from 13 (no glare) to 28 (extreme glare). The standard sets a maximum UGR per task type: 16 for technical drawing, 19 for standard offices, 22 for workshops, 25 for coarse tasks, 28 for corridors and circulation areas.

4. Colour rendering index (Ra or CRI)

A measure of how faithfully colors are rendered by artificial light. Score from 0 to 100. The standard requires Ra ≥ 80 for most workplaces, Ra ≥ 90 for critical areas (medical laboratories, printing works, quality control, painting restoration).

Values by room type (extracts)

The full standard covers more than 200 room types. These values are minima — you can always provide more light.

What's new in the 2021 version

Compared with the 2011 version, the 2021 edition brings:

• Increased illuminance values for certain rooms (effect of the ageing working population)
• Taking daylight into account as a contribution to illuminance
• Explicit mention of the non-visual effects of light (circadian, alertness, mood)
• Maintenance factors suited to LEDs
• Better-defined task area

Practical calculation

To check that a room complies with EN 12464-1, calculate the average illuminance obtained with a given luminaire layout:

Ēm = (N × Φlum × η × MF) / S N = number of luminaires Φlum = luminous flux of one luminaire (lm) η = utilisation factor (0.5 to 0.8 depending on wall reflectances) MF = maintenance factor (0.8 typical for LED) S = area of the zone (m²)

Then check: Ēm_calculated ≥ Ēm_target_standard.

Relationship with SIA 380/4 in Switzerland

The Swiss standard SIA 380/4 complements EN 12464-1 by imposing an upper limit on installed power (W/m²). A Swiss project must satisfy both: sufficiently lit (EN 12464-1) AND energy-efficient (SIA 380/4).

Calculation tools

Several options depending on project complexity:

• Manual calculation — utilance formula, sufficient for simple rooms
• DIALux evo — the reference free software, precise photometric calculation with 3D rendering (complex but powerful)
• Relux — alternative to DIALux, particularly popular in Switzerland
• CALEP in AutoCAD — command CALEP of ElectroCAD Tools, integrated into your AutoCAD workflow, 26 predefined room types with EN 12464-1 values

For everyday projects (offices, corridors, warehouses, standard car parks), CALEP is the fastest. For architectural projects with precise photometric constraints, DIALux or Relux remain indispensable.