Lighting requirements and lux: a guide to EN 12464

Good lighting is about more than being bright. For indoor workplaces there are clear requirements in the standard EN 12464-1, which specifies how much light, how evenly and with how little glare different types of spaces should have. Designing to the standard gives both a safe and productive working environment and documentation that holds up at inspection. This guide explains the three most important quantities and gives target values per space type.

EN 12464-1 applies to indoor workplaces and is complemented by EN 12464-2 for outdoor workplaces. The standard is not a law in itself, but it is often referenced in procurements, work environment requirements and insurance terms, which makes it a practical common yardstick. By designing to its values you get documentation that the client, inspector and contractor can agree on before installation even begins.

What is lux and illuminance?

Illuminance is measured in lux and indicates how much light falls on a surface. One lux equals one lumen per square metre. The standard specifies requirements for the so called maintained illuminance, which is the lowest average value that must be kept on the working plane throughout the luminaire's whole service life. This means you must size for the decline in light output and dirt over time, not just for new luminaires.

The requirement usually applies to the task area, for example the desk or a defined reference plane, not the floor. Surrounding surfaces may have lower levels but not arbitrarily low, since large contrasts between the task area and its surroundings tire the eye.

Uniformity and UGR glare

Beyond the number of lux, EN 12464 sets requirements on uniformity, expressed as the ratio between the lowest and the average illuminance. For most tasks the uniformity on the task area should be at least 0.6. Low uniformity gives patchy light and shadows that disturb.

Glare is assessed with UGR, the Unified Glare Rating, a scale where a lower value means less glare. Offices and spaces with screen based work typically have a requirement of UGR no higher than 19, while rougher industrial work may allow UGR up to 25. A third important quantity is colour rendering, measured as Ra or CRI, where most workplaces require at least Ra 80.

The standard also describes the distribution of light in the room, not just on the task area. Walls and ceilings should have a certain illuminance so that the room feels bright and open, and cylindrical illuminance affects how faces and objects appear. Colour temperature, measured in kelvin, governs the character of the light. Neutral white around 4000 kelvin is common in workplaces because it feels alert without being cold, while warehouses and industry sometimes choose higher values. All these parameters interact and should be weighed in early in the design.

Target values per space type

How to plan the installation

Start by mapping which tasks are carried out in each zone, since the requirement is driven by the task and not by the name of the space. A workshop can have several zones with different requirements. Then set the reference plane and run a lighting calculation that takes account of ceiling height, surface reflectance and the luminaire's light distribution.

1. Define zones and tasks and set the lux requirement per zone according to the table.
2. Select luminaires with the right light output, UGR and Ra for the task. See our range of indoor lighting and ceiling lights.
3. Apply a maintenance factor so the level holds over time, not just at commissioning.
4. Check uniformity and glare in the calculation before you fix the number and placement.

Do not forget controls and daylight. Presence detection and daylight regulation are not part of the lux requirement itself but decide how much energy the installation actually draws. A space designed for 500 lux rarely needs to deliver full output around the clock, and by lowering the level when no one is present or when daylight is sufficient, energy consumption can drop significantly without compromising the requirements on the task area. Bring this in during design so that luminaire choice, placement and control system work together.

A common mistake is to size for the new value and then fall below the requirement after a year or so. Another is to focus on lux and forget glare, which gives a space that is bright but uncomfortable. Use our lighting calculator to quickly estimate the number of luminaires and levels, or explore our full product range where light output, UGR and colour rendering are stated for every model. With the right documentation, both energy consumption and the working environment become predictable.