Geoff Wilkinson looks at the rules relating to emergency lighting in apartment blocks and public and commercial buildings
The Grenfell Tower tragedy has brought the issue of fire safety in buildings to the fore. No one wants to wake up and learn that a product they were involved in manufacturing, specifying or installing may have contributed to such a disaster.
While it is believed that a faulty fridge-freezer sparked the Grenfell blaze, poorly designed lighting can itself play a role in causing fires. A short-circuited light fitting, for instance, was blamed for triggering a major fire at the 63-storey Address Downtown hotel in Dubai in 2015.
Other major tragedies have involved the failure of emergency signage systems. These include the King’s Cross Underground fire of 1987, the Düsseldorf Airport fire of 1996 and the 2003 Station Night Club fire in Rhode Island.
For architects switching from single dwellings to blocks of flats, the need for emergency lighting can easily be forgotten
It is clearly important that the initial specification of lighting products and system design meets the highest standards. Architects, lighting designers and installers may have direct contractual liability to ensure that what they have designed or installed meets any specification they have signed up to – and these may well exceed minimum Building Regulations standards. In the event of a disaster you will almost certainly have to demonstrate your duty of care has been done in a competent and effective manner.
For architects switching (pardon the pun) for the first time from single dwellings to blocks of flats or commercial buildings, the need for emergency lighting can easily be forgotten or misunderstood. So where exactly do you start?
You’ll find the answer in the Building Regulations in Approved Document B Volume 2 Section 5, which stipulates that all escape routes should have adequate artificial lighting. Routes and areas listed in Table 9 (below) should also have escape lighting, which illuminates the route if the main supply fails. Bizarrely this can sometimes result in emergency lighting only being required in toilets in certain buildings.
Lighting safety table
Note that lighting to escape stairs should be on a separate circuit from that supplying any other part of the escape route.
As I mentioned above, the Building Regs are simply minimum standards and so, for example, the Approved Document still makes reference to BS 5266-1:2005, although the standard was revised in 2016. The new version of the standard now also addresses the risks that occupants face if they stay put in premises while there is a failure of the normal lighting supply – even if there is no risk from fire. For example, it may be decided that occupants are expected to stay in place for up to two hours before a decision to evacuate is taken by the fire service. Another example might be an operating theatre or an area requiring task lighting for safety such as operating machinery where failure of lighting could be life-threatening. In cases such as these, the system must be correctly designed and tested to ensure that at least three hours of lighting will be available. This procedure will already be familiar to architects designing cinemas, sports stadia and concert venues.
We are also seeing increased use of technology with lighting being used to direct people away from the seat of a fire through intelligent signage and lighting.
Typically, LEDs are added to a ‘standard’ exit sign to flash in a cycle of four steps to give the impression of a running sequence of lights, reinforcing the directional information provided by the arrow. The flashing cycle is activated only once a local detector is activated, ensuring that building occupants will not become too familiar with the concept and thus reducing the likelihood of learned irrelevance.
Signs may also be illuminated with a red ‘X’ to indicate that an exit route is not to be used. This form of dynamic signage can also be used alongside CCTV in terrorist incidents to direct people away from danger and into safe refuges and is increasingly becoming specified in high-risk public buildings.
Geoff Wilkinson is managing director of Wilkinson Construction Consultants www.thebuildinginspector.org
This article originally appeared in the October issue of AJ Specification