The growing sophistication of emergency lighting systems means that as well as being a vital part of a building’s life safety infrastructure they can also save money and reduce CO2 emissions. Julian Bailey of Hochiki Europe explains the advantages intelligent LED based solutions with advanced battery technology have over traditional systems.
Anyone who has had the misfortune of being in an unfamiliar building when a fire alarm is activated or a main lighting failure has occurred will understand the true value of an emergency lighting system. Although we often take these familiar green and white signs for granted, emergency lighting’s role, as part of an overall life safety system, should never be underestimated. Recent years have witnessed significant advancements in the technology deployed in these systems, with the result that they now offer a level of intelligence that combines energy efficiency with reliability and ease-of-use.
The way in which we use energy is constantly in the spotlight and if further proof was required of the need for all of us to address our behaviour it came in a 2013 report by the Intergovernmental Panel on Climate Change (IPCC). It stated that scientists are 95 per cent certain that we are the ‘dominant cause’ of global warming since the 1950s.
This might not come as much of a surprise. However, through greater awareness of the effects of CO2, combined with the financial implications of rising utility bills, organisations are more willing and able than ever to use energy wisely. Growing legislation and regulation means that businesses all over the world are implementing energy reduction measures. The focus is often on adopting renewable energy technologies such as solar photovoltaics (PV), wind turbines and ground and air source heat pumps as ways to generate power, while others are using building management systems (BMS) to gain a holistic view of their energy use and identify ways to lower their consumption.
However, the pressure is on to do even more, which is why building owners and managers are having to drill down and look at individual elements of their building services infrastructures to see whether there any additional savings can be made.
Light years ahead
Modern emergency lighting systems offer the possibility for significant energy and cost savings. This is due to two key factors – the use of light emitting diode (LED) based lighting and advanced battery technology.
Traditional emergency lighting systems utilise crude nickel cadmium, nickel metal hydride or lead acid batteries. They drive the centrally operated system by continually charging, discharging a little and then recharging – a process that uses unnecessary amounts of energy and quickly decreases the lifecycle of the battery. It means that battery life is limited to between one and four years, dependent upon the application.
State-of-the-art intelligent technology, however, only utilises the amount of power needed to fully charge the Emergency Lighting batteries, and then shuts the battery down until an emergency situation occurs. This avoids degradation, prolongs life and reduces energy consumption. Some systems are also available with luminaires that are equipped with integral batteries allowing continued operation for at least three hours, even in cases where the control panel or power cables are damaged. Maintained luminaires can be powered directly from the line so as not to affect any battery capacity therefore leaving the batteries in an “always ready” state.
So what sort of energy savings can be made as a result? It is estimated intelligent battery systems use between 5-10 per cent energy of that of a traditional battery system would use. Consider larger installations of up to 5,000 luminaires – which are not uncommon in hospitals, for example – and the savings soon become apparent.
It is estimated that lighting accounts for more than 19 per cent of the world’s total electricity consumption. According to Green LED Solutions, if only half of worldwide lighting was converted to LED by 2025, power use would be cut by 120GW, saving £66bn a year and reducing CO2 emissions from power plants by 350Mt over the same period.
LED lighting has seen rapid adoption and the global market was worth $25.4bn in 2013, according to a Digitimes Research Special Report. LED technology is both cost effective and environmentally friendly, making it a greener alternative to other systems that are currently available and allowing operating costs to be kept to a minimum without compromising efficiency.
LED technology is now being used in emergency lighting systems and these new luminaires offer some impressive savings. For instance, they consume less than 0.5W, while a similar 8W fluorescent light exit luminaire will use approximately 12W. These systems also come with additional energy saving features, including signage that is connected via low voltage 40V cabling, which is powered and configured on the same loop via a single panel, giving high levels of control via an automatic system.
All emergency lighting systems must be tested on a monthly basis in compliance with BS EN 50172. The test itself usually involves flicking a manual switch, which interrupts the power supply to the luminaire, so that it illuminates. A full record sheet needs to be maintained for each emergency luminaire and entered into a logbook, which must be available for inspection by the authorities at any time. Failure to provide full test records can result in legal action and closure of the building, and if the emergency lighting is defective, the insurance policy for the building may be invalid.
On the surface this all seems reasonable and fulfils the requirements of the standard, however, the testing process itself is flawed and does not necessarily result in a safe and fully functional system. All it does is check that the system works for a few seconds when the manual switch is operated – what happens if the system fails five minutes after the test? It won’t be retested for another month, so could leave a building’s occupants vulnerable in the meantime.
Also, it doesn't test just how long the luminaires will stay on for and whether the battery has enough power to maintain operation for the period specified in the relevant standards. The time required to evacuate the premises depends on its size and complexity. The duration itself is dependent not only on evacuation time but also on whether the premises are evacuated immediately the power and normal lighting fails and/or are reoccupied immediately the supply is restored.
BS EN 50172 states the minimum duration of an emergency lighting system as one hour. However, a minimum duration of three hours should be used for emergency lighting if the premises are not evacuated immediately, as in the case of sleeping accommodation, for example, or if the premises will be reoccupied immediately the supply is restored without waiting for the batteries to be recharged. It should also be noted that to comply with the National Fire Protection Association (NFPA) 101 Life Safety Code, emergency lights are required to stay lit for 90 minutes.
Modern emergency lighting control panels continuously monitor and test functionality in real time. They can also be pre-programmed to carry out specific monthly, six monthly and annual tests and it is also possible to set operational parameters up to alert when batteries are at 85 per cent capacity, providing a high level of reassurance that the system will work correctly under all circumstances.
Right place, right time
Evacuation is usually hindered by a lack of detailed knowledge of the internal connectivity of the building space, along with confusing and poorly thought out instructions. Studies have also shown that in these situations occupants usually make use of familiar routes – typically using the exit through which they entered the building. Even more worryingly, research from the University of Greenwich, as part of its study called Human Behaviour in Fire Network (HUBFIN), found that only 38 per cent of people see passive signage in an emergency.
This is a frightening statistic and only serves to highlight the importance of siting an emergency lighting system in a way that will guide people to a safe location in the event of a mains lighting failure.
BS EN 50172 offers guidance on the positioning of luminaires, provides a minimum standard that should be applied and gives guidance on specific hazards and points of emphasis that have to be accounted for. Points of emphasis are mandatory locations where lighting must highlight specific hazards, safety equipment and signs. These include areas near stairs, near changes of level, at each change of direction, near fire fighting equipment and manual call points, outside and near to each final exit, first aid points, at exit doors, and near safety signs.
Signs are either internally of externally illuminated and the maximum viewing distances for internally illuminated signs is 200 times the panel height, and 100 times the panel height for externally illuminated signs. Luminaires must offer 1Lux of output in escape routes and 0.5Lux in open areas. Emergency lighting should also be positioned in such a way to ensure that people are free from disability glare, which can prevent obstructions or signs from being properly seen.
It is worth remembering that Industry Committee for Emergency Lighting (ICEL) approved products are independently tested and meet the current product and application standards. Therefore, selecting products with ICEL approval will provide reassurance of compliance.
Look to the future
The problems with passive signage are clear from the University of Greenwich’s HUBFIN research, which is why the integration of fire detection and emergency lighting systems is the next step in adding intelligence and greater effectiveness to a life safety infrastructure.
A traditional emergency lighting system does not allow signs to be ‘shut off’, which can allow people to unwittingly travel into the path of danger. In places such as hospitals and care homes, where people often have restricted mobility, time is of the essence and must not be wasted by having to decipher the most appropriate escape route.
By integrating a fire detection system with emergency lighting, and by identifying where a fire is taking place, the correct route can be configured and communicated. For example, by responding to information sent from the fire detectors it is possible to put a red ‘X’ on specific emergency luminaires, which signals to people not to exit via that particular route. This can also be synchronised with the existing PA/VA system, adding another level of safety.
Not only does integration make good sense from a safety point of view, it has a number of cost saving and environmental benefits. It is estimated that it could reduce the entire system’s wiring content by 75 per cent, as there would be only one loop with both functions.
A correctly specified, installed and maintained emergency lighting system is crucial in order to give occupants a way of evacuating a building safely in the event of a mains lighting failure, or if required, a fire. The regulations, standards and guidance on this subject are comprehensive and the advanced LED lighting and battery technology that is now available combines reliability, functionality and usability with another way to save energy.
For more information you can visit www.hochikieurope.com or contact Hochiki Europe's Emergency Lighting Manager, Ian Watts, on 07789 228949.