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Emergency Lighting Design
Emergency lighting design proven with DIALux and Relux lux calculations to BS 5266-1 and BS EN 1838, for housing providers and commercial buildings in London.
Every design is modelled with the manufacturer's photometric data, a maintenance factor and direct light only, then checked against BS 5266-1 and BS EN 1838. You receive the lux plots, luminaire schedule and design certificate, and our engineers install from the model.
Most emergency lighting is installed by counting. BS 5266-1 lists where a fitting is needed: at each exit door, each change of direction, each stair, and near every call point and fire extinguisher. Many installers put a light in each of those places and stop there.
Those positions are only the starting point. They do not show that enough light reaches the floor. In emergency mode a fitting runs from its battery at a fraction of its normal output. On recent housing schemes we have worked on, the LED fittings gave 15% to 20% of their normal light in emergency mode. A corridor that looks bright every day can drop below the legal minimum the moment the power fails.
That is why Fire Systems Ltd calculates every emergency lighting design in professional lighting software, DIALux evo or Relux, before anything is installed. The design then becomes the installation drawing, the commissioning record and the evidence you keep for your fire risk assessor, insurer and, in higher-risk buildings, the Building Safety Regulator.
Designed Under Our BAFE SP203-4 Certification
Fire Systems Ltd holds BAFE SP203-4 third-party certification for emergency lighting, covering design as well as installation, commissioning and maintenance. Our design calculations are kept on file and checked during our SP203-4 audits.
Our Commercial Director, Will Mason, has trained in both DIALux evo and Relux, including each developer's emergency lighting course. Our Operations Manager, Milap Patel, also produces and revises designs in DIALux evo. Our installation engineers hold FIA emergency lighting training and City & Guilds electrical qualifications, and we are NICEIC registered.
What a Lux Calculation Has to Prove
Escape routes: at least 1 lux. BS EN 1838:2024 requires 1 lux at floor level along escape routes, and the 2024 edition applies it across the width of the route, not just down the centre line. The brightest point must be no more than 40 times the darkest, so people are not walking from glare into shadow.
Open areas: at least 0.5 lux. Lounges, receptions and other open areas over 60m² need anti-panic lighting so people can find their way to an escape route. Housing specifications often extend this to bin stores, plant rooms and electrical intake rooms.
High-risk task areas: 10% or 15 lux. Where someone must make a dangerous process safe before leaving, emergency lighting must give at least 10% of the normal lighting level or 15 lux, whichever is higher.
Points of emphasis. Exit doors, stairs, changes of level and direction, fire alarm call points, firefighting equipment and first aid points each need a luminaire within 2m, and safety equipment must be lit clearly enough to find and use.
How We Build a Lux Calculation
A model of the real building. We survey ceiling and mounting heights, floor levels, steps and doors, then model the corridors, stairs and landings in 3D. Small errors matter. On one housing block, the client's engineer had us lower some fittings from 2.9m to 2.5m to match the real ceilings, and the calculated average light in one room changed by more than 20%.
The manufacturer's photometric data. Each luminaire is modelled from its LDT or IES photometric file and its declared emergency output, not the brighter figure in the catalogue.
A maintenance factor. LED output falls with age and dirt, so we design with a maintenance factor, typically 0.8. The system still meets the minimum years after installation, not just on handover day.
Direct light only. Emergency calculations ignore light reflected from walls and ceilings, because in a real emergency smoke, dark finishes and dirt mean it cannot be relied on. Only light that reaches the floor directly counts.
Calculation surfaces where people walk. Corridors and landings are calculated at floor level, every stair tread separately, and open areas across the whole room. Final exits are lit outside the door to a place of safety.
Why Some Buildings Need a Calculated Design
Every building needs emergency lighting that works, but in some a design based on guesswork carries a bigger risk.
Hotels and guest accommodation: Guests are asleep and do not know the building. Long corridors, bedroom doors and changes of direction need proven light levels and exit signs visible from every point.
Sheltered and supported housing: Residents may move slowly or need help to leave. Stairs, ramps and changes of level must be lit well enough to prevent falls during an evacuation.
High-rise and higher-risk buildings: The stair is the only way out. Every tread and landing needs to be calculated, and the design forms part of the golden thread.
Converted street properties: Narrow stairs, low ceilings, half-landings and steps in corridors are exactly where counted-in fittings leave dark spots.
Plant rooms, bin stores and intake rooms: Housing specifications increasingly require anti-panic lighting in these rooms, and the light levels have to be shown, not assumed.
Not sure whether your existing emergency lighting was ever designed? We can survey the building, model it and show you where the light levels fall short.
What You Receive With Every Design
Every Fire Systems emergency lighting design is issued with:
A luminaire layout showing the position and mounting height of every fitting and exit sign
Lux plots showing the minimum, average and uniformity for each escape route, stair and open area
A schedule of the fittings, with their photometric data and emergency output
A BS 5266-1 design certificate
The calculation file, kept with your handover documents
Our engineers install from the model, using the exact X and Y position and mounting height of each fitting, so what goes on the wall matches what was calculated. Every installation is then commissioned and certified, and the design stays on file for future alterations, periodic photometric verification and, in higher-risk buildings, the golden thread.
Five questions to ask any emergency lighting installer
Can you show me the lux calculation for my building, and which software produced it?
Whose photometric data did you use, and what is the fitting's output in emergency mode?
What maintenance factor did you design to?
Were the stairs calculated tread by tread, and the escape routes across their full width?
Will I receive the calculation and the design certificate at handover?
If the answer is a layout drawing with no figures on it, the lights have been placed, not designed.
Once the design is agreed, the same team can carry it through: see emergency lighting installation and emergency lighting testing and maintenance.
“Placing lights is not the same as proving them. Every Fire Systems emergency lighting design is backed by a lux calculation.”
Designed in DIALux evo and Relux, reviewed against BS 5266-1 and BS EN 1838, and installed by our own engineers.
In Practice: Engineer-Reviewed Designs for a London Housing Association
On a London housing association's fire alarm and emergency lighting programme, Fire Systems Ltd produced emergency lighting designs for blocks of flats on the programme. Each design was reviewed by the client's chartered building services engineers before installation.
The design. We modelled each block in DIALux evo, calculating both the normal lighting and the emergency lighting for corridors, stairs, entrances, bin stores and electrical rooms.
The review. Each design went through detailed comments: stairs calculated tread by tread, corridors at floor level, anti-panic areas in bin stores and electrical rooms, corrected mounting heights, and final exits lit outside to a place of safety. We revised the models until the engineers confirmed the light levels.
Installation. Our engineers were given the exact position and mounting height of every fitting, taken from the approved model, so the installation matched the calculation.
Self-test systems. Where the client later specified a manufacturer's self-test and web-monitored system, the manufacturer modelled its own luminaires and we checked each calculation against the specification. On recent stairwells the darkest point on each tread and landing was calculated at between 12 and 20 lux, against a minimum of 1 lux.
Emergency Lighting Design Questions We Are Often Asked
Does emergency lighting need a lux calculation?
BS 5266-1 sets out where emergency luminaires should go, but BS EN 1838 sets the light levels they must achieve: 1 lux on escape routes, 0.5 lux in open areas and 10% of normal lighting or 15 lux in high-risk task areas. The only reliable way to show a design meets those levels before it is installed is a photometric calculation using the manufacturer's data. Housing provider specifications increasingly require these calculations in DIALux or Relux.
What are DIALux and Relux?
They are professional lighting design programs used by lighting designers and engineers across Europe. They model a building in 3D, load the photometric files for real luminaires and calculate the light reaching every point on the floor, stairs and walls. Fire Systems uses both to design and verify emergency lighting.
Why is emergency lighting dimmer than normal lighting?
In emergency mode the fitting runs from its battery at reduced output, often 15% to 20% of its normal light for the LED fittings we install. That is expected, and it is exactly why a design must be calculated on the emergency output, not the normal output shown in the catalogue.
Can you check whether an existing system meets the light levels?
Yes. We survey the building, record the existing fittings and their positions, and model them using the manufacturer's data. Where the calculation shows areas below the minimum, we recommend where fittings should be added, moved or upgraded.
Do you design the normal lighting as well?
Where the specification calls for it, yes. On housing projects we have calculated normal lighting levels for corridors, lobbies, bin stores and electrical rooms alongside the emergency lighting, so both are reviewed and approved together.
