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Blog: Emergency lighting - exploiting the best of LED, PoE and DALI technology to deliver user-centric systems

The evolving technology of LED and Power over Ethernet (PoE) combined with the DALI standard, provide more options than ever before to produce emergency lighting that is not just compliant, but convenient.

The challenge

Emergency lighting is a legal requirement for every commercial and public building. Under the Regulatory Reform (Fire Safety) Order 2005, building owners and tenants must ensure that spaces remain safe in the event of the mains power supply being lost. Emergency lighting is a key element of this and generally considered under three main types:

  1. Escape route lighting – to ensure that building occupants can follow a safe and unobstructed route out of the building
  2. Open area/anti-panic lighting – required in any open space over 60m2 to avoid panic and allow occupants to orient themselves
  3. High risk task area lighting – to ensure safety can be maintained while necessary shut down procedures are followed

An emergency lighting system must provide adequate illumination throughout the designated escape route(s) and at certain key positions, including: corridor intersections; elevators; where changes in floor level occur; at fire alarm points; and where firefighting equipment is sited.

In a large building, this can mean a lot of space requiring emergency lighting provision, and more equipment generally means more expense. The good news is that with LED and Power over Ethernet technology – combined with the DALI standard – we can deliver streamlined and cost effective solutions that exceed minimum standards.

LED and emergency lighting

The low energy consumption and longer lifespan of LED luminaires make them an increasingly popular choice for commercial applications, where reduced energy bills and equipment longevity hold strong appeal for facilities managers. In installations where style is a consideration, the reduced size and greater versatility of LED technology makes it an attractive option when lighting must confirm to the interior design scheme.

In the context of emergency lighting requirements, the ability of LED lamps to deliver a specified light level as soon as they are switched on – without the ‘warming up’ delay of many energy efficient options – is a perfect tool to meet the legal requirement to provide emergency lighting immediately when mains power is lost.

Benefits of DALI

Digital Addressable Lighting Interface (DALI) is a network-based system for lighting control. It’s a system that we use heavily at Prolojik because of the benefits it can deliver for a wide range of clients, including reduced installation and maintenance costs, and greater control over their lighting systems, particularly when partnered with a user-friendly interface such as our Perspective software.

In terms of emergency lighting, a DALI system delivers its greatest benefit when it comes to undertaking statutory testing. Emergency lighting systems must be checked every month to ensure the back-up power supply and lamps are working; and a ‘drain’ should be run annually. This is when the emergency system is brought into operation for the minimum legal duration to ensure that the lighting system works as intended, and that the back-up batteries recharge successfully when mains power is restored.

At its simplest, this testing process can be carried out manually: once the emergency luminaires have been activated, a straightforward floor-walk will identify any lamp faults. When mains power is restored, a second floor-walk checks that all batteries are recharged. In a small building this may be fine. But in most commercial buildings this time-consuming process is a drain on resources and presents a risk of human error either during the floor-walk, or in the records kept of the test and subsequent maintenance.

With a DALI system in place, it becomes unnecessary to floor-walk because, not only does each luminaire report its own light output level and any faults during testing, but a DALI system allows luminaires to be continually monitored, locating and addressing faults without waiting for the next scheduled test. To undertake this type of proactive system maintenance manually would be too resource intensive in most cases. With a DALI system is in place, the only additional cost to consider is the central testing system interface.

The power of a combined approach

The benefits of LED and DALI technology are fully unlocked when normal and emergency lighting are combined within the same luminaires on a single system.

The long life of LED lamps makes them ideal for use in luminaires which will provide both normal and emergency lighting. As an additional bonus, LED lamps can emit required emergency lighting levels below their full power output, extending the back-up battery life required during loss of mains power.

With a DALI system in place, the lighting control network doesn’t require a secondary mains supply, reducing the wiring required as well as the associated costs of materials and installation. No sensors are needed to report how lamps are functioning, because DALI luminaires self-report their activity via the network: another cost avoided.

In this combined approach, the LED luminaires in normal use are driven by the mains power supply and managed by the DALI interface, which is also mains connected. Luminaires are programmed to divert to back-up power whenever the DALI signal is lost with no need for additional signalling to the luminaires, producing a highly reliable system.

Where does PoE come into it?

The combination of Power over Ethernet (PoE) with a DALI lighting system using LED lamps is the pinnacle of efficiency and effective management of emergency lighting.

Constructing emergency lighting on a PoE network delivers further cost savings as there is no need for any copper mains cabling, and the need for specialist electrical installation is reduced. Ongoing costs are minimised as PoE uses around 11% less energy than an LED system powered by a 240V mains supply.

Power over Ethernet technology opens up a range of opportunities to use LED technology in new ways. One exciting possibility would be to communicate dynamic information to building occupants via the lighting system. While emergency lighting is in operation, it could become possible to indicate safe evacuation routes, or unsafe areas to be avoided, by commanding the LEDs to produce a range of predetermined colours.

Emergency lighting is a critical health & safety function and by combining the best features of LED and Power over Ethernet technology, with the DALI standard, we have the tools to create reliable, robust and cost effective emergency lighting that is shaped around, and driven by, the needs of the end user.