The revolution being brought by LEDs

White LED luminaires offer many advantages over other types of lamp.
Not only can switching to white LED lighting from other light sources bring big improvements in radically reduced maintenance and increased energy efficiency, but LEDs also deliver many more practical and business benefits. Roy Burton explains what LEDs can bring to the world of modern building services.Maintaining lighting in large spaces can be an expensive matter. First, high ceilings and hard-to-access light fixtures mean that work can be disrupted while maintenance takes place, often involving external contractors. That means you most likely prefer to plan your maintenance schedule to avoid unexpected disruption, so you cannot afford to wait until the lights fail before replacing them. Then there is the lifespan issue. Halogens lamps last about 3000 h at most, some fluorescents will give you up to 15 000 h and high-pressure sodium up to 22 000 h — but they will all fail at some point. For that reason, many organisations plan their replacement schedule based on half the expected life of the light source, and, of course, the maintenance contractors are well pleased. Solid state LED light fixtures can radically improve on these lifespan figures. Not only are they guaranteed for 50 000 h, but they are actually more likely to last for 100 000 h. Even then they do not fail, but simply fade to about 70%. That means you can fit them and forget them for at least five years, so there is zero maintenance cost and zero business disruption. Another benefit is the reduced exposure risk for maintenance workers associated with traditional lamp and ballast replacement. On top of LEDs’ zero maintenance requirements, organisations can also benefit from their lower energy requirements. Dialight’s LED luminaires, for example, are warranted for five years. A 90 W luminaire can replace a 150 W HID lamp, saving 40% on energy. Being semiconductor-based LED luminaires are built for frequent switching off and on, unlike HID and fluorescent lights, so you save even more power by avoiding the need for 24/7 lighting. This ability to turn the LEDs off when no one is in the area or there is no need for artificial lighting makes them ideal for integrating with energy-saving controls and also substantially extends their lifespan to as much as 10 years. Some low-traffic areas such as cold stores can benefit greatly from LEDs’ ability to switch on and off. Cold stores are typically lit with fluorescent lighting, but the lights are left on 24/7 because their tube life is reduced by switching in temperatures of -25°C. Not only is our LEDPAK LED model more efficient in such low temperatures, it can be switched off or dimmed when there is no one working in the area, which is typically from 50 to 90% of the time, and brings a substantial energy saving. In less extreme environments the lower operating temperature of LEDs means there is less heat output for air conditioning to contend with — another winning feature for saving energy. As ‘smart’ lights, LEDs have the further attraction of ‘instant-on’ ability, unlike HIDs which can take a while to warm up when switched on. Their ability to achieve full brightness in a fraction of a second makes LEDs very practical for use as safety lights in areas like walkways and car parks, where they can be left off or dimmed and triggered to come on by proximity switches when someone enters.
LEDs can produce CCTV footage that is more useful for security purposes than light sources with a poorer colour rendering.
As safety lights, LEDs have the added benefit of superior colour rendition over sodium lights, which make everything look a muddy orange, so LEDs will let you find your car easily at night in a crowded car park and produce much more useful CCTV footage for security purposes. In addition, their ability to focus light directionally rather than spraying it around like conventional light sources makes them more efficient and reduces light pollution into the sky or into the windows of adjacent buildings. When it is finally time to dispose of them, LEDs are safe and easy to recycle, as they contain no mercury or other hazardous materials. Current white LED technology produces a bright, high-quality light well suited to large public spaces like malls, concourses, terminal buildings, rail and bus stations, sports and exhibition centres, warehouses and their associated car parks and loading bays. Compact versions are also finding their way into architectural use for coves, cornices and exterior features as well as in retail shelving, point-of-purchase and refrigeration displays. Producing LEDs for offices and more general commercial illumination is a challenge that the solid-state lighting industry is now tackling with vigour. Western office workers are accustomed to the neutral, warmer light produced by incandescent and fluorescent lights, so we have set ourselves a target for 2010 of attaining the same warm white light with the more efficient LED light output and the competitive prices that high volume will bring. Once these objectives are achieved, we anticipate that solid-state lighting will become the general lighting system of choice and that the overall efficiency of lighting will rise considerably. LEDs truly are a revolution in lighting technology. Compared to conventional lights, they are like the iPod compared to the gramophone — light years ahead. Roy Burton is CEO of Dialight
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