We’re often asked, ‘What’s the point of designing emergency lighting? Surely if I install enough emergency luminaires around the building they will give enough light?’
Our response is usually, ‘Yes you can do that, however it’s unlikely to comply with regulations and you will only discover this after construction is complete and the system is tested.’
The reason for this is simple, emergency lighting is not only about providing enough light for people to find their way out of a dark building, it’s about ensuring:
- The correct light levels for the space, e.g. open plan office, escape route, machine room and warehouse all have differing requirements
- Uniformity is within required limits, i.e. there is not too much difference between darker and lighter areas
- The correct signage is used in the required positions, e.g. changes in corridor direction, exit points, extinguisher locations
We regularly see refurbishment projects where the building already has an emergency lighting system. Little thought is given to the impact on the emergency lighting when the layout is changed which often leads to the system failing testing once the project is completed.
This case study demonstrates how we redesigned the emergency lighting for the refurbishment of a large office building to accommodate a major UK company’s global corporate HQ.
The layout of the large open plan floors was changing to include various meeting rooms, kitchens and breakout areas. This involved erecting partition walls and sections of new ceiling to include 600×600 LED panels. It was decided the existing fluorescent fittings (some of which are emergency fittings) would be relamped.
- Audit the existing system
Undertaking an audit of the existing system allowed us to measure the true emergency light output rather than assuming the standard 10% of full brightness. This provided a strong foundation to base the design work upon.
- Calculations for existing system
We created a 3D model in our lighting software and using the light output measurements we populated the model with luminaires that had a light output and spread very closely matching the measured values.
This allowed us to accurately model the new layout and understand the problem areas requiring additional lighting.
Using the model from the previous stage we added new unmanaged emergency luminaires to supplement the existing fittings. After several iterations we produced a design that gave the required minimum light level of 0.5lux and a uniformity of less than 1:40.
The design used the absolute minimum of new emergency luminaires, keeping purchase and installation costs as low as possible.
- Handover to contractor
Following approval of the design we added an emergency lighting layer to the project CAD plan detailing the position of all new luminaires. This ensured the contractor could easily install per the design.
The emergency lighting system was tested towards the end of the overall project and passed for both light level and uniformity.