What lux level is required for a classroom?

BB101 typically requires 300 lux maintained on desks for general teaching. Higher levels may apply for specialist subjects.

How is maintained illuminance different from initial lux?

Maintained lux accounts for lamp depreciation, dirt, and room surface reflectances. Always quote maintained values on issued designs.

What about emergency lighting lux levels?

Emergency escape routes require minimum 1 lux at floor level (BS 5266). Anti-panic open areas need 0.5 lux minimum. These are separate from general lighting design.

BuildFlo Design Guide · Electrical · BS EN 12464-1

Lighting design lux levels for UK buildings

Maintained illuminance by space type under BS EN 12464. Built-in lux calculator for offices, classrooms and corridors.

Lighting design starts with maintained illuminance - the lux level on the task plane after accounting for lamp lumen depreciation, dirt, and room surfaces.

LG7 and BS EN 12464-1 are the usual references for non-domestic interiors. Emergency escape lighting is separate - BS 5266 / BS EN 1838.

Typical maintained illuminance (indicative)

Space	Maintained lux	Notes
General office ( written/typed work )	500	LG7 open plan often 300-500 per brief
Meeting room	300-500	Dimmable often requested
Classroom ( general teaching )	300	BB101 may specify 300 maintained
Corridor	100
Stair ( escape route )	150 min ( emergency )	See BS 5266
Open-plan escape route	1 lux min floor level ( emergency )	Anti-panic: 0.5 lux
Plant room	150-200
WC	200
Retail sales area	300-500	Depends on merchandise

Always confirm UGRL ( glare ) and UGR limits for offices - typically ≤19 for computer work.

Lumen method - quick sizing

E = ( N × Φ × UF × MF ) / A

Where:

E = maintained illuminance ( lux )
N = number of luminaires
Φ = lumens per luminaire
UF = utilisation factor ( often 0.5-0.7 )
MF = maintenance factor ( often 0.7-0.8 )
A = room area ( m² )

Use the calculator below to size luminaire count or check achieved lux.

Design workflow

1. Room classification - BS EN 12464 category and task type. 2. Target lux - From brief or table above. 3. Luminaire selection - Lamp lumens, distribution, LOR. 4. Lumen method or modelling - Dialux/Relux for final design; lumen method for first pass. 5. LPD check - Part L limiting luminaire efficacy / building LPD where applicable. 6. Emergency lighting - Separate calculation on escape routes and open areas >60 m².

Common mistakes

Quoting initial lux instead of maintained - lamps depreciate.
Forgetting room surface reflectances - UF drops in dark rooms.
Mixing up emergency ( 1 lux escape ) with general ( 500 lux office ) on the same drawing.

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*For full Dialux-level layouts use modelling software - this guide is for first-pass MEP sizing and brief checks.*

Frequently asked questions

What lux level is required for a classroom?: BB101 typically requires 300 lux maintained on desks for general teaching. Higher levels may apply for specialist subjects.
How is maintained illuminance different from initial lux?: Maintained lux accounts for lamp depreciation, dirt, and room surface reflectances. Always quote maintained values on issued designs.
What about emergency lighting lux levels?: Emergency escape routes require minimum 1 lux at floor level (BS 5266). Anti-panic open areas need 0.5 lux minimum. These are separate from general lighting design.