Planning cleanroom lighting

The short answer

Start with the tasks in each room and the light level EN 12464-1 sets for them: typically 500 lx for pharmaceutical production and general laboratory work, and 1,000 lx or more for precision assembly, colour inspection and operating theatres. Then fit the luminaires around the filter fan units and air diffusers, which take priority in a cleanroom ceiling. Choose luminaires that suit the ceiling system and the maintenance route, from the room or from the void above. Plan emergency lighting and controls at the same time, not afterwards.

Light levels for common tasks

EN 12464-1 gives maintained illuminance (Em), the level that must not be fallen below over the life of the installation, for each task. It also sets limits for glare (UGR), uniformity (U0) and colour rendering (Ra). The values below are for the task area, as commonly published from the standard.

Task or area	Em (lx)	Ra	Notes
Pharmaceutical production	500	80	UGR 22, U0 0.60
Laboratories, general lighting	500	80	UGR 19
Colour inspection	1,000	90	Higher CRI matters as much as the light level
Precision assembly (electronics, measuring equipment)	1,000	80
Electronics testing and adjusting	1,500	80
Food production (delicatessen, preparation)	500	80
Operating theatres, general lighting	1,000	90	UGR 19. The operating field has its own surgical light.
Pre-op and recovery rooms	500	90

The 2021 edition of EN 12464-1 also gives higher “modified” values for where the task is more demanding, such as small detail, low contrast or older workers. Many pharmaceutical and hospital clients have their own design guides with higher figures, so check those first. These values are a starting point: always confirm them against the current standard and your client’s specification.

Uniformity and glare

• Uniformity. EN 12464-1 sets a minimum ratio of the lowest to the average illuminance on the task (U0), often 0.60. Even light helps inspection and avoids dark patches between filter units.
• Surrounding areas. The area around the task should be lit to a level related to the task, so the eye isn’t constantly adapting.
• Glare. UGR limits are typically 19 to 22 for these tasks. In laboratories and inspection rooms, where people look up and across the room, low-glare panels with micro-prismatic diffusers (UGR below 19) are worth considering.
• Reflections. Glossy surfaces such as stainless steel benches and glass vials reflect bright luminaires. Matt or anti-reflective diffusers and careful positioning reduce this.
• Maintenance factor. Clean rooms stay clean, but diffusers still lose some light over time, and LEDs depreciate. Use a maintenance factor based on the luminaire’s lumen maintenance data (for example L90 at a stated number of hours) and your cleaning regime.

Working around filters and airflow

In a cleanroom ceiling, air handling comes first. HEPA or ULPA filter fan units (FFUs), terminal filter housings, return grilles and sprinkler heads fix much of the layout before lighting is considered.

• Get the ceiling plan early. Lay luminaires out on the same grid as the filters, and coordinate with the HVAC designer and ceiling contractor.
• ISO 7 to 9 rooms usually have filters at intervals, with room for standard recessed panels between them.
• ISO 5 and cleaner rooms with unidirectional (laminar) flow may have filters across most or all of the ceiling. There’s little room for recessed panels, so linear luminaires fitted to the grid between filter units are often used. Streamlined profiles reduce disturbance to the airflow below.
• Avoid shadows from filter housings and deep grid members, especially in rooms with lower ceilings.
• Check heat. LED luminaires add far less heat than older lamps, but the load still counts in the room’s heat balance.

ISO 14644-4 covers the design and construction of cleanrooms, including how services are coordinated.

Ceiling systems

Ceiling	What to check
T-grid (modular suspended)	Module size (typically 600 × 600 or 1200 × 600 mm), grid profile and whether it is gasketed or gel-sealed. Luminaire size must match the grid, and the luminaire needs to seal to the grid.
Plasterboard or metal panel	Cut-out size and tolerance, how the luminaire is fixed and how the gasket is compressed.
Walk-on (load-bearing)	Panels that maintenance staff can walk on from above. Check whether luminaires are installed and serviced from above, and any load the luminaire itself must take.

Our recessed panels fit modular grid and plasterboard ceilings. Some luminaires in the range open from the ceiling side, for maintenance from above. Check each product page for the ceiling types it suits.

Maintenance from the room or the void

How luminaires will be maintained affects the choice of product.

• Room-side maintenance is simpler to arrange, but opening a luminaire in the room breaks its seal and can release particles. It is usually planned during shutdowns, followed by cleaning and, where needed, requalification.
• Ceiling-side maintenance, from a walk-on ceiling or plenum, keeps the room sealed while drivers and LED modules are changed. It suits rooms that run continuously or where opening the ceiling would mean recertification.
• Long LED life reduces how often maintenance is needed. Check the stated lifetime (for example L90/B10) and driver lifetime separately.

Emergency lighting

Cleanrooms need emergency escape lighting like any other workplace, and gowning rules and airlocks can make escape slower. In the UK and Ireland, BS 5266-1 and EN 1838 set the requirements. EN 1838 asks for at least 1 lx along the centre line of escape routes, 0.5 lx in open areas, and, in high-risk task areas, at least 10% of the normal maintained illuminance and no less than 15 lx. High-risk areas may include rooms with dangerous processes or machinery that must be shut down safely.

Emergency luminaires in clean areas should be as well sealed as the general lighting. Options include self-contained versions with integral batteries and luminaires on a central battery system. Battery maintenance and testing should be planned so they don’t disturb the room. Ask us which products are available in emergency versions for your project.

Controls

• On/off is common in cleanrooms that run all day, and keeps the installation simple.
• DALI dimming suits rooms with variable use, setting levels at commissioning (constant light output), and linking to a building management system. Many of our luminaires are available with DALI drivers.
• Presence detection saves energy in support rooms, stores and corridors. In production cleanrooms, make sure detectors don’t switch lights off while someone is working still, and that the detector itself is sealed and cleanable.
• Keep control gear outside the room where possible, and seal any sensors that sit in the ceiling.

How we can help

Send us room data sheets, the reflected ceiling plan with filter positions, and the class or grade of each room. We can run lighting calculations with real photometric data and propose a layout that fits the ceiling. Start a project.

Sources: EN 12464-1:2021, Light and lighting, Lighting of work places, Part 1: Indoor work places; ISO 14644-4, Cleanrooms and associated controlled environments, Part 4: Design, construction and start-up; EN 1838, Lighting applications, Emergency lighting; BS 5266-1, Emergency lighting, Code of practice for the emergency lighting of premises.