Dr. S. S. Verma, Department of Physics, S.L.I.E.T., Longowal, Distt.-Sangrur (Punjab)-148106.
Emergency lighting
Today we all are almost dependent on electricity driven lighting use rather than natural lighting so power loss to a building can cause un-comfort, loss of time or panic amongst occupants, resulting in anxiety, depression, injury and emotional distress. Emergency lighting is put in place so that when the power supply to ‘normal’ lighting fails, and there is sufficient lighting to allow almost every normal lighting-based desired activity in general. Importance of emergency lighting are: to offer comfort and safety to occupants in an emergency and giving emergency services better visibility. With advances in technology, emergency lighting now offers a range of technologies and features to implement high standards and smart features more regularly seen with general lighting, to provide safety and well-being of building occupants in addition to providing additional benefits. Smarter devices now offer the advantage of better control, efficient operation and aid in on-going maintenance to improve functionality, usability and the expected lifetime of the product. Improvement in the technology of emergency lighting gives businesses the opportunity to further progress the safety of their buildings and the protection of their employees and occupants. The advances and developments in LED and wireless technology for emergency lighting again illustrate the continuing importance of this safety feature in the workplace and other buildings, whether commercial or communal residential areas.
The basic elements relating to emergency lighting are ‘maintained’ or ‘non-maintained’. Maintained emergency lighting is on all of the time and stays on if the power fails. It would typically be used in public places where people may not be familiar with exit routes. Non-maintained emergency lighting only comes on when the power fails and is typically found in workplaces where people are more familiar with escape routes. The emergency lighting is powered by a battery system, which may be self-contained (located in or near the light fitting) or a central battery system serving a number of luminaries. Emergency lighting products can be classified as standalone (e.g. illuminated exit signs or bulkhead luminaries) or converted mains luminaries that contains emergency lighting components to run the luminaries; albeit at a reduced output from the battery if the power fails. Most luminaries’ manufacturers will offer an emergency option within a product portfolio. Aesthetically it looks the same but has the added components for emergency operation.
A well designed, installed and maintained emergency lighting system, combined with a fit for purpose fire alarm system is an essential part of any buildings’ life safety system. In the event of a power cut, fire or any disaster affecting the power supply to the building and endangering staff and visitors the emergency lighting luminaries will illuminate and guide them to the appropriate escape routes and emergency exits, ensuring a safe and efficient evacuation. Utilized throughout all building types, across all industries, the complexity of emergency lighting systems varies greatly depending upon the size, type and purpose of the building. Advances in emergency lighting systems have ensured that full compliance can be maintained without detracting from the interior aesthetic of your premises. In order to ensure the safe exit from a site the emergency lighting system luminaires must maintain a standard duration of lumination. Regular maintenance visits from a qualified Swift Fire & Security engineer ensures that the period of lumination is in accordance with British and European standards.
Recent technological trends
Incorporating light-emitting diodes (LEDs) in red or green exit signs has been one of the most important technological advancements in emergency lighting. “Most exit signs in the industry now use this technology as it has become cost-competitive when compared to other traditional illumination sources, is long-lived, and is more energy efficient,” said Paul Brodowski, product manager for Lightolier. And, because of improved efficacy, white LEDs are now beginning to be bright enough to use for emergency-lighting applications such as pathway lighting, according to Ertz. There has also been a recent increase in using self-diagnostic systems in emergency-lighting applications. These systems can perform a variety of self-diagnostic functions that regularly analyze the unit’s performance, verify its operation and alert the appropriate department of problems. “This trend is being driven by facilities wanting ways to more easily comply with national requirements that 30-second operational tests of units are conducted each month,” said Brodowski. Another technological trend has been the increased use of nickel metal hydride (NiMH) batteries for both pathway and exit-sign lighting. NiMH, according to Brodowski, provides batteries with longer life, higher efficiencies and an operating temperature range between 14 and 113 degrees Fahrenheit. They are also nontoxic.
Implementation of emergency lighting
While advances in the general lighting technology are heavily publicized, it is easy to overlook the similar advances that have been made in emergency lighting. Like most lighting technologies, emergency lighting has undergone some significant changes in recent years; particularly in relation to automatic monitoring and testing, use of LED light sources and the emergence of wireless communications. The basics remain the same though. The fundamental purpose of emergency lighting is to come on automatically in the event of a power failure. This ensures that light levels are sufficient for people to find their way to safety. The major differences between general and emergency lighting, is that safety is paramount and other factors, such as energy efficiency, are secondary considerations. Nevertheless, the introduction of LED light sources for emergency lighting has clearly resulted in a reduction in the power consumption of these systems, resulting in financial and environmental benefits for end users. The main financial savings, though, arise from the introduction of automated systems and their ability to simplify monitoring, testing and ongoing maintenance. Another consideration, and one that is often overlooked, is the visual appearance of the emergency lighting fittings. It is probably true to say that in the past, compliance with emergency lighting legislation has often been achieved at the expense of the aesthetics. Many luminaire manufacturers are now introducing standalone LED emergency fittings that complement their general lighting products so that aesthetics do not need to be sacrificed for the sake of compliance.
It’s vital that emergency lighting systems are implemented in the correct areas of a building and adhere to all relevant standards, to ensure that everyone, no matter which part of the premises they work, can escape safely and appropriately. It’s important to carry out a risk assessment when installing any emergency lighting in order to know which areas of the building are at a higher risk of danger so that all procedures are followed correctly and safely. Emergency lighting is crucial at both the start of an emergency and towards the end. Speed and efficiency will allow many of the occupants to escape unscathed, but a more complicated emergency can cause difficulties. The emergency lighting duration may be dependent upon the premise, with sites such as care homes, student accommodation and hospitals requiring 3 hours emergency output. Different work areas require different emergency lighting requirements, all of which should be consulted on before building work takes place. These include:
Escape route lighting: gives people the chance to identify a means of escape, so they can exit the building appropriately
Emergency escape lighting: allows occupants to leave a building safely and enables people to tackle any danger if required
High risk task area lighting: emergency lighting that is implemented in areas where occupants are at higher risk from danger
Open area lighting: employed to minimize panic and allow occupants the chance to find an appropriate escape route, with minimal anxiety
LED emergency lighting
While incandescent and fluorescent lights are still effective and popular, new advances in technology have led to LED emergency lights becoming the top choice for emergency crews. Benefits of LED emergency lighting include:
Efficiency: Incandescent light bulbs get very hot when they burn and almost all the energy they produce goes to heat making with inefficient. The filament that incandescent bulbs burn to create light also wears out very quickly, resulting in lights that need to be replaced regularly. LED lights don’t rely on burning a filament, so there is no need to worry about heat or wear and tear. In fact, using LED emergency light bulbs often results in energy savings of 30 percent compared to normal bulbs. LED emergency light bulbs function in much the same way as incandescent bulbs, but they are thinner and lighter, making them more efficient and economical. LED lights are highly robust, have excellent low temperature performance, and are easily digitally controlled. This form of lighting is also space-efficient. The light can be much more focused to its exact purpose, leading to significant savings over the installation’s life. Best of all, LED lights rely on their own dedicated optics, drivers, and fittings, allowing for sleek, unobtrusive luminaire designs.
Lifespan: Since LED lights don’t rely on a burning filament to generate light, they can last much longer than incandescent light bulbs—as many as 50,000 hours or more. LED emergency lights bulbs have been used to power exit signs for several years now, with technology continuing to progress and costs continuing to decrease.
Brightness: LED emergency light bulbs are much brighter than other kinds of lights—in fact, they’re some of the brightest types of bulbs available. They usually do have to be clustered in order to maximize their effectiveness, which slightly cuts their efficiency. Even so, their brightness is unparalleled, and they can easily be seen from maximum viewing distances.
Emergency Lighting Benefits
Emergency lighting comes in a variety of types and can therefore provide a variety of functions – that may or may not be used strictly during emergencies. Broadly speaking, the functions are as follows:
- Emergency escape lighting:provides illumination of escape routes, signs and special areas to help people safely leave the premises
- Emergency safety lighting:provides lighting to help people safely move through a premises and/or leave the premises
- Standby lighting:powered by an alternate power supply, this lighting provides sufficient illumination to continue normal operations in the event of a total failure in mains power
The market for LED-based emergency lighting systems is arguably one of the most mature. Although LED devices have been suitable for simple exit signs for about 20 years now, they have only become feasible for use in emergency lighting systems in the last 6 years. Improvements in the efficacy and color consistency of white LEDs, as well as price reductions, have been the catalysts for change. Technology continues to evolve and prices erode, making LEDs steadily more applicable in a wider range of emergency lighting systems. Furthermore, innovative design combined with the advantages of LED technology can provide an important competitive edge for lighting designers. Advances in battery/energy storage systems for back-up operation and circuit protection devices, as well as the LEDs themselves, are creating new opportunities. This article will review the state-of-the-art technology in LED-based emergency lighting systems, with emphasis on new component developments. For example, improved efficiency, cooler running, lower power, and more rugged LEDs are improving reliability and cutting maintenance costs. Circuit protection solutions add peace of mind for emergency lighting in safety-critical applications and especially where there is a risk of fire or explosion. Devices such as LED shunt protectors are popular options here. Finally, battery technology has evolved rapidly in recent years, with the trend towards lithium ion offering smaller, higher-power battery back-up solutions. However, in certain safety-critical applications these are considered a fire risk unless properly protected. An alternative, and sometimes complementary, solution is the ultra capacitor.
Acknowledgement: The use of information retrieved through various references/sources of internet in this article is highly acknowledged.