White light - Just a choice of colour or more?
There's a new light in town - and on motorways, bridges, pedestrian areas and carparks - and that's white light. For comfort, safety and security the latest white light technologies can offer immediate energy savings on installation and a better respect for the environment.
Historically, outdoor lighting solutions have been dominated by the high-pressure sodium lamp, due to its high efficiencies and reliability. The stats are hard to beat - with an impressive lm/w output that has kept this technology in favour across much of Europe.
Compared with CMH or LED technologies, it's fair to say that high-pressure sodium lamps still hold their own when it comes to energy efficiency. However, their distinctive yellow light gives poor colour rendering, meaning it is difficult to distinguish colours. What CMH and LED can offer above HPS is the option of white light - and it's within the intricacies of what this has to offer, that the benefits start to stack up.
Much closer to daylight, the ambience of white light is perceived as being brighter because you can distinguish colours more easily. This, in turn, makes a person feel more secure and comfortable in their surroundings as it enables easier recognition of people's faces and other details. It also acts as more of a crime deterrent and makes for clearer CCTV images.
In addition, for road users studies have shown that a car driver's reaction time (mesopic vision) is at least six times higher under white light and the higher colour rendering also improves obstacle recognition.
Whilst white light is ideal for creating the best possible surroundings for citizens, in today's climate it would still be difficult to justify the technology on this alone, without a credible environmental stance.
With governmental commitments to the Kyoto agreement, there has been a drive to cut energy usage across all aspects of life - and this has been seen as a key contributor to the move towards white light in outdoor space, as the higher S/P ratios can mean light levels can be reduced.
Recognising this, when using white light for road lighting, designers can drop one CIE lighting class. Of course, the major wins are in the optimisation of white light in application. LED's, for example, are a more directional light source - meaning there is less diffusion of light where it's not required. Luminaires have been developed that achieve 0% upward light, reducing light pollution and light nuisance. This coupled with the general feeling of a brighter, more natural ambience is ideal for carparks in built up areas, for example.
About GE Lighting
GE Lighting invents with the vigor of its founder Thomas Edison to develop energy-efficient solutions that change the way people light their world in commercial, industrial, municipal and residential settings. The business employs about 15,000 people in more than 100 countries, and sells products under the Reveal® and Energy Smart® consumer brands, and Evolve ™, GTx™, Immersion ™, Infusion ™, Lumination® and Tetra® commercial brands, all trademarks of GE. General Electric (NYSE: GE) works on things that matter to build a world that works better. For more information, visit www.gelighting.com.
For more information about GE Lighting's products visit the product pages of GE Lighting Europe.
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