EN 12464-1:2021 lists hundreds of lux targets, and Saudi specifications are mostly written against it. Here is the practical sub-set that decides whether your office, mosque, hospital, or mall actually passes commissioning.
Four ideas to carry into the next specification conversation you have.
Em is a maintained illuminance on a defined task area, at a stated plane. A desk task sits at desk height, ward general lighting is specified at floor level, and rack picking is judged on the vertical rack face.
Design initial = Em / MF. At MF 0.80 a 500 lux target needs about 625 lux on handover day. EN 12464-1:2021 requires the designer to state the maintenance factor and the maintenance schedule (6.3, 8.6).
Uo = Emin / average. Office and classroom task areas ask for Uo ≥ 0.60, the immediate surrounding area for ≥ 0.40 and the background for ≥ 0.10. Two designs can share an average and only one pass.
UGRL ≤ 19 for offices and classrooms, ≤ 22 for retail sales areas, back to 19 at the till. UGR is calculated for a room, a layout and an observer position; Annex A covers non-standard rooms.
Maintained illuminance Em on the task area, per EN 12464-1:2021 Clause 7. Read the whole row, not the lux: the plane, the uniformity and the glare limit are part of the same requirement.
| Space | Em (lux) | Reference |
|---|---|---|
| Office, writing / typing / reading | 500 | EN 12464-1:2021, Clause 7 · Uo 0.60 · UGRL 19 |
| Corridors and circulation | 100 | EN 12464-1:2021, Clause 7 · at floor level · Uo 0.40 |
| Classroom, general | 300 | EN 12464-1:2021, Clause 7 · Uo 0.60 · UGRL 19 |
| Classroom board | 500 | EN 12464-1:2021, Clause 7 · vertical · Uo 0.70 |
| Hospital ward, general lighting | 100 | EN 12464-1:2021, Clause 7 · at floor level |
| Hospital examination | 1,000 | EN 12464-1:2021, Clause 7 |
| Surgical field (the luminaire, not the room) | 40,000-160,000 | IEC 60601-2-41 · central illuminance at 1 m |
| Mosque prayer hall | agree per project | no Saudi mandatory table; specify against the task |
Retail and storage per EN 12464-1:2021 Clause 7; roads per SASO 2927:2019, which classes Saudi streets M, C and P. Outdoor work places have their own part, EN 12464-2.
| Space | Em (lux) | Reference |
|---|---|---|
| Retail sales area | 300 | EN 12464-1:2021, Clause 7 · UGRL 22 |
| Retail till area | 500 | EN 12464-1:2021, Clause 7 · UGRL 19 |
| Storage rack gangway, unmanned | 20 | EN 12464-1:2021, Clause 7 |
| Storage rack gangway, manned | 150 | EN 12464-1:2021, Clause 7 · judged on the vertical rack face |
| Packing and dispatch | 300 | EN 12464-1:2021, Clause 7 |
| Road, motorised traffic, M1 to M6 | 2.0-0.30 cd/m² | SASO 2927:2019 · road-surface luminance, not lux |
| Conflict areas, C0 to C5 | 50-7.5 | SASO 2927:2019 · average illuminance |
| Pedestrian areas, P1 to P6 | 15-2 (avg) | SASO 2927:2019 · plus a minimum per class |
Five practical rules that turn a number into a passing installation.
Em is what the installation must still deliver when the interval runs out, so the initial design level is Em / MF: at MF 0.80, a 500 lux target is about 625 lux on day one. The factor itself is computed, not guessed: MF = LLMF × LSF × LMF × RSMF per CIE 97:2005, using the real cleaning interval and the real environment. EN 12464-1:2021 makes stating both the factor and the schedule a duty of the designer (6.3, 8.6).
Two designs both averaging 500 lux: one with Uo = 0.70, one with Uo = 0.35. The second fails even though the average matches. Spacing is not a rule of thumb either: take the maximum spacing-to-height ratio from the luminaire's own photometric file, then prove the resulting grid against Uo in the model.
EN 12464-1:2021 gives reflectance ranges of 0.7-0.9 for ceilings, 0.5-0.8 for walls and 0.2-0.6 for floors (5.2.2). A room with dark surfaces returns less interreflected light, so the same luminaires deliver less to the plane. How much less depends on room proportions, distribution and the direct/indirect split: take the delta from the model at the real surface values, never from a fixed percentage.
There is no Saudi mandatory illuminance table to quote: SBC 401 is the Saudi Electrical Code and contains no lux requirements. So specify it explicitly instead. Name the task (reading at mat level against congregational prayer), name the plane, name the target and the uniformity, and get it agreed before anyone models it.
SASO 2927:2019 classes Saudi roads as M (motorised traffic), C (conflict areas) and P (pedestrian areas). M classes are specified in road-surface luminance, 2.0 down to 0.30 cd/m², not in lux; C and P classes are illuminance. And the class is computed, not chosen: class = 6 − the sum of weighting values over speed, traffic volume, traffic composition, carriageway separation, junction density, parked vehicles, ambient luminance and visual guidance.
We don't quote until we model. Every NLC submission includes a DIALux report showing Em, Uo, UGR per space, against EN 12464-1.
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