How many lux does an office need?

It depends on the task, not on the room. Writing, typing, reading and data processing need 500 lx maintained on the task area, with a modified value of 1000 lx where the context calls for it. Filing and copying need 300 lx, CAD workstations and meeting rooms 500 lx, technical drawing 750 lx, a reception desk 300 lx and archives 200 lx. All are maintained values: they must still be reached at the end of the installation’s life.

What UGR is required for office lighting?

RUGL 19 for offices, meeting rooms and classrooms; 16 where the work is precise or the screen task critical; 22 at a reception desk and 25 for archives. It is a class, not a measurement — ≤ 19 means a calculated value between 16.5 and 19.4, and the series runs 16, 19, 22, 25, 28. A “UGR < 19” figure on a datasheet is not that result: it is what the luminaire reaches in a standard 4H/8H room, and glare is a property of the installation, not of a luminaire.

Do the requirements apply to the whole room or the desk?

To the task area. The 2021 edition sets requirements per work area rather than per room, so the desk carries the full value. A band at least 0.50 m around it is lit to a ratio of that value, capped at 500 lx and floored at 150 lx, at Uo 0.40 or better; the background beyond — at least 3 m wide, or up to the wall — sits at a third of that level, Uo 0.10 or better. A floor-wide average proves nothing on its own.

What changed for offices in EN 12464-1:2021?

Three things matter for an office. The tables gained a second illuminance column, a modified value for the context of the task which is explicitly not a maximum, with seven conditions deciding whether you climb one step or two. Wall, ceiling and cylindrical illuminance moved into those same tables per activity — for desk work 150 lx cylindrical, 150 lx on the walls and 100 lx on the ceiling. And requirements are stated per work area instead of per room.

Does Momik use the EN 12464-1 office values automatically?

Yes. Draw or upload your zones and each type automatically gets the right standard values, so the office rows are not looked up and typed in per zone. Momik then calculates maintained illuminance, uniformity (Uo) and UGR per zone and checks each one against the standard values for that room type, and the PDF report lists the result zone by zone. The published standard stays the authority for the room you are designing.

EN 12464-1 office lighting requirements

Q: Do the requirements apply to the whole room or the desk?

To the task area. The 2021 edition sets requirements per work area rather than per room, so the desk carries the full value. A band at least 0.50 m around it is lit to a ratio of that value, capped at 500 lx and floored at 150 lx, at Uo 0.40 or better; the background beyond — at least 3 m wide, or up to the wall — sits at a third of that level, Uo 0.10 or better. A floor-wide average proves nothing on its own.

Q: What changed for offices in EN 12464-1:2021?

Three things matter for an office. The tables gained a second illuminance column, a modified value for the context of the task which is explicitly not a maximum, with seven conditions deciding whether you climb one step or two. Wall, ceiling and cylindrical illuminance moved into those same tables per activity — for desk work 150 lx cylindrical, 150 lx on the walls and 100 lx on the ceiling. And requirements are stated per work area instead of per room.

Q: Does Momik use the EN 12464-1 office values automatically?

Yes. Draw or upload your zones and each type automatically gets the right standard values, so the office rows are not looked up and typed in per zone. Momik then calculates maintained illuminance, uniformity (Uo) and UGR per zone and checks each one against the standard values for that room type, and the PDF report lists the result zone by zone. The published standard stays the authority for the room you are designing.

What the standard asks of an office

Four numbers travel together for every task. Ēm is the maintained illuminance in lux, the average the installation has to hold on the reference surface. “Maintained” is the load-bearing word: it must still be reached at the end of the installation’s life, after lamps age and surfaces collect dirt. Uo is the minimum uniformity inside that zone, Ra the minimum colour rendering index for the activity, RUGL the glare limit — the highest Unified Glare Rating allowed.

Three zones, one inside the other

The task area carries the full requirement. Around it runs the immediate surrounding area, a band at least 0.50 m wide in the working plane, lit to a ratio of the task value — capped at 500 lx, floored at 150 lx — at Uo 0.40 or better. Around that is the background, at least 3 m wide or up to the wall, at a third of that level, Uo 0.10 or better.

The requirement belongs to the task, not the room

The 2021 edition sets its criteria per work area, not per room, so “an office needs 500 lux” is only ever true of the desks. An open-plan floor with desk rows, a copier corner, a meeting table and a reception point carries four sets of values at once, and a floor-wide average proves nothing about any of them. momik.ai/en-12464-1 covers these quantities across all room types; the office lighting requirements below stay inside that one group.

Quantities, zones and the maintained-value rule: IBE-BIV, Guide pratique de l’éclairage des lieux de travail intérieurs, November 2023, pages 10, 11 and 16 — https://ibe-biv.be/wp-content/uploads/2023/11/IBE-BIV-NBN-EN-12464-1-2021-Guide-pratique-de-leclairage-des-lieux-de-travail-interieurs-adjust.pdf — requirements set per work area: https://www.cibsejournal.com/technical/work-light-balance-key-changes-to-workplace-lighting-guidance/

Lighting levels per office task

These are the EN 12464-1 lighting levels for an office: the required minimum maintained illuminance on the task area of each activity, with the uniformity, colour rendering and glare limit from that row.

Task or activity	Ēm (lx)	Uo	Ra	RUGL
Writing, typing, reading, data processing	500	0.6	80	19
Filing, copying and similar	300	0.4	80	19
Technical drawing	750	0.7	80	16
CAD workstations	500	0.6	80	19
Conference and meeting rooms	500	0.6	80	19
Reception desk	300	0.6	80	22
Archives	200	0.4	80	25

Two rows are publicly available with the 2021 modified illuminance as well: filing and copying moves from 300 to 500 lx, desk work from 500 to 1000 lx, where the context of the task calls for it. For the other five no public source we could check prints that column, so no figure is given — the mechanism is identical, one step up the standard’s illuminance ladder, where 500, 750 and 1000 lx are consecutive levels.

Sources. Rows one and two, modified values included, are reproduced from figure 6 of the IBE-BIV Guide pratique, which prints them with the credit “Source EN 12464-1”: https://ibe-biv.be/wp-content/uploads/2023/11/IBE-BIV-NBN-EN-12464-1-2021-Guide-pratique-de-leclairage-des-lieux-de-travail-interieurs-adjust.pdf. CAD workstations, conference and meeting rooms, the reception desk and archives come from the published summary at https://www.techlumen.gr/en/guide/lighting-standards-guide/. Technical drawing comes from ETAP’s Dossier EN 12464-1: https://www.etaplighting.com/sites/default/files/uploads/Dossier%20EN%2012464-1_AT_EN_A4_lr.pdf — the same dossier prints 0.6 for the reception uniformity where the summary prints 0.4, and 0.6, the stricter of the two, is shown above. Two cautions. No public source we could verify prints the 2021 modified column for these five rows, so that column is left out rather than guessed. And of the technical drawing row only the 750 lx is confirmed by a 2021 source, the IBE-BIV guide on page 15; its Uo 0.7 and RUGL 16 rest on ETAP’s dossier, which describes the 2011 edition. The office group runs longer than seven rows; the complete table is only in the published standard, sold as NBN EN 12464-1:2021 in Belgium (https://www.nbn.be/en/buying-standards/how) and BS EN 12464-1:2021 in the UK (https://knowledge.bsigroup.com/products/light-and-lighting-lighting-of-work-places-indoor-work-places-2).

Uniformity, glare and colour in practice

Uo is a rule about the layout

Uniformity is a floor on how uneven a zone may be, set per zone: 0.60 on desk work, 0.70 on technical drawing, 0.40 in the band around the task, 0.10 on background, walls and ceiling. No luminaire choice repairs it — spacing does. Light cannot stop at the desk edge, because the 0.50 m band has its own illuminance ratio and its own Uo 0.40, and the background beyond it still has to reach a third of that band. One relief arrived in 2021: points inside a band next to the wall may be excluded from the uniformity calculation.

UGR ≤ 19 is a class, and it belongs to the installation

Offices, meeting rooms and classrooms are limited to RUGL 19; precise work or critical screen tasks tighten it to 16, a reception desk is allowed 22 and archives 25. The limits run 16, 19, 22, 25, 28 — steps of three, because that step is a noticeable change in glare. The class is the unit, not the decimal: ≤ 19 means a calculated value between 16.5 and 19.4, so 19.1 and 19.6 sit in different classes.

A datasheet reading “UGR < 19” is not that result. ZVEI is blunt: glare is a property of a lighting installation, not of an individual luminaire, and the datasheet figure is what that luminaire reaches in a standard 4H/8H room at 20 % floor, 50 % wall and 70 % ceiling reflectance. What moves it is geometry: each luminaire’s contribution is divided by the square of the Guth position index — its distance from the line of sight — so where the desks face is part of the answer. The tabular method fixes two observers mid-wall, horizontal at 1.2 m seated eye height, along and across the luminaires; no diagonal direction exists in it, and it holds only for rectangular rooms between 2H and 12H, H measured from eye level to the mounting plane.

Ra 80 is a floor, not a differentiator

Every office row asks a minimum colour rendering index of 80 — the same for archiving as for technical drawing. It rules products out; it does not choose between two that both clear it.

Per-zone uniformity values and the office glare classes: IBE-BIV guide, pages 16, 27, 28 and 29. Wall-band exclusion: https://www.cibsejournal.com/technical/work-light-balance-key-changes-to-workplace-lighting-guidance/ — limit series, class boundaries, the 4H/8H datasheet room, the position index and the 2H–12H range: ZVEI / licht.de, Position paper UGR method – application and limits, October 2021, https://www.licht.de/fileadmin/Publications/ZVEI_Publications/2110_E_ZVEI_UGR_method.pdf

Walls, ceilings and the 2021 edition

The 2021 edition moved wall, ceiling and cylindrical illuminance into the requirement tables, per activity — CIBSE and Fagerhult confirm the move independently. Desk work asks 150 lx mean cylindrical illuminance, 150 lx on the walls and 100 lx on the ceiling; filing and copying 100, 100 and 75 lx. In small cellular offices the wall requirement applies to the front wall, and at least 75 lx may be accepted for the others.

Cylindrical illuminance is the quantity most offices never had calculated. It measures light arriving on a small vertical cylinder instead of on the horizontal plane, which decides whether a face across a desk reads properly; CIBSE puts the useful band at 50 to 150 lux. Treat the older general minima as history — ETAP’s dossier on the 2011 edition records walls above 50 lx and ceilings above 30 lx, 75 and 50 lx in enclosed rooms; the 2021 office row asks 150 and 100.

The second illuminance column

Beside the required value the 2021 tables carry a modified one, taking the context characteristics of clause 5.3.3 into account — and the Belgian guide states it cannot be read as a maximum. Seven conditions decide whether you move: tasks critical for safety or economic value, increased concentration, exceptional precision, observers with poorer vision such as older workers. One or two apply, one step up; more than two, two steps. Raising the task value raises the room with it — cylindrical, wall and ceiling each move a step. The standard’s own worked example is an office: with relatively many older employees, the design team raises one specific zone from 500 lx to 750 lx.

2021 office row values, the front-wall exception, the seven conditions and the worked example: IBE-BIV guide, figure 6 and pages 15-18 — https://ibe-biv.be/wp-content/uploads/2023/11/IBE-BIV-NBN-EN-12464-1-2021-Guide-pratique-de-leclairage-des-lieux-de-travail-interieurs-adjust.pdf — independent confirmation of the move into the tables: https://www.cibsejournal.com/technical/work-light-balance-key-changes-to-workplace-lighting-guidance/ and https://www.fagerhult.com/knowledge/light-planning/en-12464-1/lighting-of-indoor-workplaces/standard-en-12464-1-in-brief/ — the 50/30 lx and 75/50 lx general minima come from ETAP’s dossier on the 2011 edition and are shown here as 2011 values only.

Designing an open-plan office: a worked example

No number here is invented. This is the order of operations.

Map the zones task by task — desk rows, copier corner, meeting table, reception, archive — each with its own reference surface, band and background.
Take the row per zone: Ēm, Uo, Ra and RUGL, plus the cylindrical, wall and ceiling values from it.
Check the seven context conditions per zone, not per floor. The standard’s own example raises one zone and leaves the rest.
Fix the maintenance factor before the layout. Ēm is a maintained value, so the same grid passes or fails on that factor.
Put a calculation grid on each reference surface, then place the luminaires. The result is read off that grid, so the spacing belongs in the report.
Check and report per zone. One pass or fail for the whole floor hides the zone that failed; for glare, split it into rectangles between 2H and 12H first.

For the arithmetic of one zone, the comparison on the Momik homepage carries a worked set: an office of 46.6 m² at 500 lx, a maintenance factor of 0.787, and twelve 600×600 LED panels per supplier in a 4×3 grid, calculated with the Momik calculation engine.

How Momik applies these values

On an office floor the claim that each type automatically gets the right standard values reads like this: a zone typed as desk work brings 500 lx, Uo 0.60, Ra 80 and RUGL 19 with it, the filing corner beside it brings 300 lx and Uo 0.40, a drawing station 750 lx and RUGL 16. The seven rows above stop being a lookup.

From there the catalog is filtered on what that zone needs — lux and UGR alongside IP, CCT, CRI and mounting — and one click returns illuminance, uniformity, UGR and isolux per zone. Each is checked against the values for that room type on its own reference surface, never on a floor-wide average, and the PDF report prints the outcome zone by zone with heatmaps and a luminaire list. No summary replaces the published text: for the office you are designing, NBN EN 12464-1:2021 and its national equivalents are the only authority.

Office lighting requirements under EN 12464-1