EN 12464-1 — what really changed with the 2021 edition
There is no 2025 edition: SN EN 12464-1:2021 is the one in force. What it changes compared with 2011, from modified illuminance values to walls and ceilings, and why it sets no requirements for melanopic effects.
The edition in force is EN 12464-1:2021, adopted in Switzerland as SN EN 12464-1:2021. There has been no newer edition or amendment so far; what appeared in 2025 was a new edition of Part 2 for outdoor workplaces. This article shows what actually changed in the 2021 edition compared with 2011, and what the standard says about non-visual effects of light.
Edition and status
CEN approved EN 12464-1:2021 in May 2021. Member countries had to adopt it by February 2022 and withdraw the 2011 edition. In Switzerland, the SECO guidance on Art. 15 of Ordinance 3 to the Employment Act refers to SN EN 12464-1 and treats its values as minimum values that must be met. For workplaces, the standard is therefore more than a recommendation.
Required and modified illuminance
The most visible change is in the tables. Alongside the required maintained illuminance (Ēm,r) there is now a modified value (Ēm,u). Which one applies depends on context modifiers, conditions that justify higher visual requirements. Examples include:
- critical visual tasks or errors with high follow-up costs
- very small details
- visual tasks of long duration
- little daylight
- below-average eyesight of the users
If one or two of them apply, the requirement rises by one step on the illuminance scale; if more than two apply, by two steps. The modified value is a design target, not an upper limit. The context modifiers should therefore be agreed with the client and documented before any calculation.
Walls, ceilings and cylindrical illuminance
Requirements for illuminance on walls and ceilings and for cylindrical illuminance now appear directly in the tables for each type of area. The values themselves are largely not new, so the standard has not become stricter. But anyone who used to verify only the work surface now finds the other values in the same place.
The task area, the immediate surrounding area and the background area are also described in more detail. A strip along the walls, 15% of the smallest room dimension and no more than 0.5 m wide, may be excluded when calculating uniformity.
Glare and flicker
For glare, the tabular UGR method remains authoritative, with the familiar limit steps of 16, 19, 22, 25 and 28. The requirements for shielding have been clarified, and a new informative annex covers UGR in situations that the standard method does not address.
Flicker and stroboscopic effects are covered in more detail, but the standard sets no limit values of its own. Common metrics are PstLM and SVM. Binding limits for light sources are set in the EU by Ecodesign Regulation 2019/2020, with PstLM ≤ 1.0 and SVM ≤ 0.4.
Melanopic effects: informative only
EN 12464-1:2021 deals with non-visual effects of light, such as those on the circadian rhythm, only in an informative annex. It contains no requirements or limits for melanopic quantities. Metrics such as melanopic EDI or melanopic DER are defined in CIE S 026:2018, not in EN 12464-1.
Anyone who wants to design for non-visual effects will find recommendations in DIN/TS 67600:2022. It supplements EN 12464-1 and gives a guideline value of 250 lx melanopic EDI. This is not a requirement of the standard.
What this means for lighting design
- Design and verify to the 2021 edition. DIALux evo supports it from version 11, including context modifiers.
- Agree the context modifiers with the client and document them in the lighting concept.
- Include the wall, ceiling and cylindrical values from the tables in the calculation, not just the work surface.
- Ask luminaire manufacturers for the flicker metrics PstLM and SVM.
- Agree melanopic targets as an explicit client requirement, as a supplement to the standard rather than one of its requirements.