Emergency Lighting Design

Unlike mains lighting schemes which are centered around aesthetics and visual comfort, affording the designer ample opportunity to showcase their individual artistic flair, an emergency lighting system is a legal requirement, and as such, is governed by industry standards and other such legislation. This in turn leads to a much more formulaic and formal scheme.

This may be a common perception; however, emergency lighting designs require a much more detailed eye. They should remain consistent to the criteria set out within the building risk assessment, and not influenced by over-zealous clients and consultants, who in turn may perceive emergency lighting as a necessary but visually detrimental supplement to the mains lighting scheme. By its very description, emergency lighting can be interpreted as a supplement to a lighting scheme, but, in essence, it is a safety critical system which should be afforded the same level of importance as fire prevention, smoke alarm and sprinkler systems. Each of these resources are parasitic and as such, lay dormant for a large percentage of their designed life, but occupants must have the utmost faith that when required, they will operate accordingly to help protect them

Emphasis Points
The risk assessment deems that certain areas within the building are categorized according to their severity of risk or by physical factors. The areas to focus on are; high risk task areas which require increased light levels, escape routes and open areas. Within each of these areas certain points require the focus of an emergency light, these are known as emphasis points. Emphasis points, as the name suggests, require not only light during emergency situations but specific emphasis, this is managed by placing an emergency luminaire within 2 metres of them. Emphasis points vary from way markers at changes of level or direction to focused light upon safety equipment and muster points for people under increased risk.

As all areas require emphasis lighting, this is often the best place to start when designing emergency lighting. Due to the high lumen levels and intensity of modern LED emergency lighting, a room with its emphasis points illuminated often does not require much additional lighting to satisfy the minimum level. The drawback of the previously mentioned emergency luminaire is an effect known as spotting, where the uniformity of a room is lost and it becomes a patchwork of light and dark areas. This is very difficult to manoeuvre through in a true emergency as your eye cannot quickly adjust to the ever changing light level. To combat this effect emergency lighting should have a uniformity level of no more than 40 to 1.

Exit Signage
Once the desired light level is achieved, the designer must also consider emergency exit signs, also known as ‘running men’. These green pictograms are required to direct unfamiliar people out of the building in an emergency situation. Requirements state that the signs must be of the same design and be unambiguous in their instruction. Because of this the designer should imagine themselves at any point of the building in the event that they must escape. To minimise impact on energy usage, areas with occupants familiar and comfortable can be designed to use non-maintained signs which only activate upon loss of mains power. In areas where the occupants do not know the general lay out and will likely have not had a safety induction, exit signs should be illuminated at all times. It should be noted that emergency situations can often happen without the loss of mains power, but this does not change the panic and disorientation that can occur without signage that is easy to follow.

Choosing the right luminaire
Once all of the above has been taken into account, the choice of which emergency luminaire to use can be considered. Standalone emergency luminaires, which can be spaced up to 15 meters apart, are readily available in minimalist designs which provide all the light required whilst maintaining the rooms aesthetics. For truly invisible lighting a mains luminaire can be converted using an emergency conversion kit, these luminaires do suffer when the light distribution is originally intended for mains lighting requirements and not emergency, and can also be prone to a lack of maintenance with regards to cleaning. Design maintenance factors are added to allow for this but designer assumptions versus real life application can sometimes leave a building with impaired emergency lighting.

The emergency lighting designer must therefore do their best to not only design a safe and compliant space on day one, but anticipate the usage of that building for the years to come.