Chris Slattery, Global Product Manager for Emergency Lighting at Tridonic reviews the current state of emergency escape lighting and considers what needs to be considered when designing fresh solutions. He then goes on to examine in more detail the implications of changes in battery technology and how this can impact on the challenge of reliable emergency lighting provision.
As the construction of ever larger and higher buildings continues and increasing numbers of us live in dense, multi-occupancy urban developments, the emergency lighting market is one that shows no signs of diminishing. However, whilst many aspects of construction appear to embrace the modern technologies and approaches that are influencing the ways in which we live and work in the 21st century, emergency lighting has shown little sign of change. Why is this? Well one reason might be that you can’t take a chance on something that quite literally may make the difference between life and death. Changes to emergency lighting products should only be implemented after the completion of the most rigorous and time consuming test procedures. Changes in regulations must be incorporated into the law of the land, pertinent to the building in which they are being installed. With demands like this there are easier products on which lighting companies may prefer to spend their R&D budget.
Emergency escape lighting is traditionally split into three key areas; the first is the provision of emergency light which will alleviate panic and enable occupants to identify their escape routes. The second is the lighting found along the escape routes, more often than not corridors and stairways, and in locations containing fire-fighting and safety equipment,. The final is known as high-risk or hazardous emergency lighting relating to the safety of people involved in a potentially dangerous process or situation and provides the required levels for the proper shut down procedures to be followed. An example would be a laboratory handling hazardous materials but I remember seeing a lighting scheme where a kettle was considered a “high-risk area”. Each country has their own requirements with regards to illuminance levels and some have differences in the respective applications (e.g. theatres).
Regardless of the type of emergency lighting each of these options has typically relied on either nickel–cadmium (NiCd) or nickel–metal hydride (NiMH) battery chemistries. These traditional chemistries suffer from a high self-discharge and are therefore required to be consistently recharged. Whilst the power usage may seem insignificant per battery, if we then multiply this hundreds of times across a building or suite of buildings then you soon get far more significant figures. This in turn equates to wasted energy, increased heat, and associated unnecessary costs, all things that FM managers are constantly striving to reduce.
Whilst the luminaires and their components may be viewed as products, lighting itself is a service and people need to be able to rely upon it. Improved reliability not only offers building owners and facility managers financial savings it should mean that both they and their occupants can sleep at night, without fear of darkness and panic descending should the unimaginable occur. It seems over the recent years that the lighting industry is following the development path of many other technical industries that form a part of our daily lives. Think about mobile phones; 10 years ago, you could replace the battery in your phone with ease. Nowadays you can’t even get the back off the market leading devices without voiding the warranty. Lighting is moving in the same direction, gone are the days of replacing a failed tube, if an LED fails a common strategy seems to be just install the cheapest edge-lit panel found in the local wholesaler. This is not a strategy we can afford to use when it comes to emergency lighting.
The regulation of the emergency lighting market is now at a tipping point. Regardless of where you are in the world the building regulations and standards, however complex and comprehensive they may be, are lagging behind the latest advances in luminaire and battery technology. At the same time, with images of fires in high rise buildings across several countries, people need to think again about their attitude to emergency lighting. A re-evaluation is long overdue and no longer should emergency lighting be selected solely on a cost per unit basis.
Batteries are the weakest link
In the early part of this century LEDs became far easier to produce and consequently the lighting industry has undergone a revolution in the last twenty years. The decline of the fluorescent tube means more light, for lower cost, in a smaller unit and this is now an accepted norm. Architects are able to specify highly efficient and effective units that have both an aesthetic and functional role. This is great until the luminaire designers try to add batteries into the products that typically have a restricted internal air flow and a body that is acting as a heatsink for the LEDs. Once you get into the realm of >50°C the lifetime of batteries will shrink rapidly. With LEDs now the accepted light source, it became clear to those in the market that an alternative battery solution would be required to take emergency lighting to the next level. Most components inside the luminaire have either a three, five or even eight year guarantee and this had led to a “fit and forget” mentality. However, with NiCd and NiMH manufactures are still only able to offer an emergency luminaire where the battery guarantee is limited (typically only one year), this is quite clearly a safety risk if these products are not properly maintained.
Lithium-ion batteries have been in existence for some time and nearly every other battery powered product, from laptops to cars, are embracing this technology. In fact, in many countries emergency lighting is one of the few applications where NiCd batteries are still permitted to be used. Lithium-ion batteries typically offer a longer lifetime and a lower self-discharge. It is these properties that make it suitable for emergency lighting where we simply want to charge the battery and keep it near full capacity until it is needed.
However, it is not as simple as just choosing an alternative battery type. To find the next suitable battery technology Tridonic has spent the past four years completing some of the most rigorous product and component testing to have been undertaken in the lighting industry. Starting with a choice of multiple different chemistries and cell types, each underwent a stringent review designed to test every aspect of the technology (shown below). After all these had been completed only one cell remained and it is this that has been used in the newest emergency lighting product to have entered the global market.
- Initial safety testing to IEC 62133.
- Accelerated life testing.
- Further technology & safety testing including high temperature resistance, external & internal short circuit, and flammability.
- 3rd party data audit.
- Supplier audit covering both manufacturing and delivery processes
- Generation of battery certificates
- Quality agreements – ensuring no changes would be made to any manufacturing process without prior agreement of Tridonic.
- Electrochemical breakdown – cell breakdown for quality analysis.
- Batch testing including x-ray on every manufacturing run.
- Ongoing internal quality and lifetime testing.
Whilst certain lithium based chemistries gave major advantages in lifetime and temperature rating the only cell that safely satisfied all testing was a specific lithium iron phosphate option. There were further challenges to overcome for example the strict UN regulations around how they, or a product of which they are a component, can be transported.
The new product is a dedicated emergency downlight defined by its compact design and ease of installation. It exceeds all lifetime and safety requirements and offers interchangeable lenses inside the box to meet the different applications. The three testing variants BASIC (manual), SELFTEST and PRO (DALI) can be combined with one or three hours of operation, the PRO unit also offers two hours. Moreover, there is an option of maintained or non-maintained operation. To give that little bit more we have also incorporated the first generation of our BlackBox recording technology that stores and records all operating information and faults that may occur.
But whilst this investment in new battery technology should certainly give a bit of clarity on the future for emergency lighting there are still two areas where there is much needed room for improvement. The first being whilst more and more emergency lights are self-testing, as opposed to manual test, there is still a requirement for someone to record and more importantly review and then respond to what the data is telling them. Even if you are confident in your emergency lighting’s self-test procedures, if no-one is actually rectifying a failure when it is notified then regardless of the battery technology, the emergency lighting will not be there when required. The second area may be to start to encourage building owners to fully test their emergency lighting systems as they do the fire alarms. We’ve all been in buildings where a full fire evacuation procedure is tested but have any of you ever been in a building when the main lights have been extinguished and you have had to find your way, even in a building with which you are familiar, with only the emergency lights? It may be more disruptive but one day that test procedure may prove to be a life saver.
For more information, go to www.tridonic.com