Lighting & Signage
With a new code of practice for emergency escape lighting and incandescent lamps now history, we discuss the implications, report on the impact of developments in LED technology on internal and external lighting and look at the way designers and manufacturers are responding to this.
As the opening and closing ceremonies of the London 2012 Olympic and Parlympic Games showed, lighting is an extraordinarily powerful design medium. Architects would do well to fight tooth and nail to ensure that project cost plan allocations for lighting, especially external lighting, are adequate, if no generous. Of course, this is easier said than done as lighting, and again external lighting in particular, happens at the tail end of projects.
One fundamental that project teams will not be able to skimp on is emergency lighting and it’s a good idea to set aside at least half an hour of quality CPD time to familiarise yourself with BS 5266-1:2011, the most recent revision to the code of practice for the emergency escape lighting of premises.
‘The Standard now contains documentation for small systems that are designed, installed and verified by a single engineer’, says Fire Industry Association trainer Chris Watts. ‘It also includes a checklist for engineers to report on the condition of existing premises where the original documentation is not available.’ The new standard also overhauls references to European Standards, particularly EN 1838, 50171, 50172, and explains their requirements. BS 5266-1 now gives advice on potential problems, along with practical instruction, warning against glare from emergency lighting which can prevent occupants from using escape route or reading signs. High light output luminaires such as beam projector units should be mounted at least 30 degrees from the normal line of sight.
Technical specific values for lighting engineers are still referenced in BS EN 1838. ‘The International Standard for exit signs has been voted positive’, observes Watts, ‘and BS 5266-1:2011 reflects this change to what should now be a single unified format.’ Emergency lighting level standards in BS EN 1838 have changed: the ‘A Deviations’, which allowed 0.2 lux on the centre-lines of some escape routes and 15 second response times have been removed and the minimum level in the UK is now 1 Lux. Emergency lighting is now required within five seconds, in line with other European countries. Guidance for the protection of specialised risks and a checklist for the assessment of existing installations previously issued in BS 5266-10 are now included in BS 5266-1:2011. ‘Hopefully the new format of BS 5266-1 will be easier to understand and will help users to develop emergency lighting systems to match the installations defined in their risk assessments’, says Watts.
As of 1 September 2012, the UK government has effectively banned the production of general use incandescent lamps. ‘Inefficient light sources started to be phased out in the UK in 2009, starting with most frosted lamps and clear incandescent sources over 80W’, explains Artemide technical lighting consultant Luke Locke-Wheaton. ‘Over the past 4 years, ever- increasing numbers of incandescent lamps have effectively been removed from the market.’ Clear incandescent lamps over 7 Watts recently joined this prohibited list. The government has also introduced strict new measures in Approved Document L: conservation of fuel and power. ‘As lighting manufacturers, we need to future-proof existing products and ensure new ranges adopt technology that meet these strict requirements’, says Locke-Wheaton. ’ Artemide has therefore invested heavily in research and development of new technologies, especially light-emitting diodes, known as LEDs.’
Luminaire size has a big impact on efficiency. ‘Traditionally, larger housings allowed big reflectors to be used, maximising and harnessing all the flux emitted by the lamp, but with LED’s it’s the size of the heat sink that is critical’, says Locke-Wheaton. ‘The measure of efficiency was generally taken to be the output of a bare lamp compared with that of the combined lamp and luminaire, but this notion became unclear after LED technology was introduced.’ Heat, and therefore the junction temperature of the LED chip, is all-important when calculating LED efficiency and Artemide has invested heavily in developing heat sinks that draw heat away from LED chips.
Although larger fittings and heat sinks are generally more efficient, they also have greater visual impact. Artemide’s Copernico and Ipparco fittings were developed to achieve a good balance between optical performance and visual comfort, maximising efficiency without compromising holistic design criteria and aspirations to explore formal possibilities and challenge expectations.
Lighting manufacturer Philips’ Designer bulbs offer a new approach to lighting design which separates the optic from the light bulb. Designers can select the brightness and then the effect in combination, exercising more control and able to swap and change at will. As LEDs have such a long life, this helps to build in flexibility. Philips’ Master LED range, with dimmable glow effects, has been developed to radiate warm light in all directions, as a low energy substitute for incandescent lamps, suitable for retrofit projects where they facilitate the switch to LED technology.
Turning to the external environment, Woodhouse lighting development manager Guy Harding says, ‘The industry is undergoing a fundamental change with the advent of LEDs and it is almost as if traditional discharge lamps and luminaires no longer exist, but discharge lighting still has its place and LEDs may not be suitable for all applications.’ Harding emphasises the need to consider LED life, sealing, lens design, efficiency of power supplies and maintenance when specifying LED luminaires. Designers need to check that LEDS can be replaced if they fail prematurely. Unlike discharge lamps, LEDS are not replaced on three or four year cycles and their light output at end of the module’s life must be considered.
‘LEDs behave very differently to traditional light sources’, says Harding. ‘Discharge lamp outputs are indicated on manufacturers’ data sheets and when they are coupled with reflectors of known efficiency, luminaire output is easily measured.’ Harding notes that the luminous flux and lumens per Watt figures on LED data sheets assume low junction temperatures, with LEDs flashed on and off briefly, but these figures cannot be used for real situations with LEDs fitted in luminaires, as junction temperatures, or temperatures of LEDs, are much higher due to heating effects.
‘The photometric distributions now available with LEDs give very different results when trying to design to lighting standards’, says Harding. ‘It’s much easier to achieve minimum lighting requirements now with averages which are significantly lower than for traditional discharge sources, and although both lighting types can meet the standard, the “hot spots” under discharge lamps can be avoided with LED lenses which improve the light spread.’ Harding recommends comparing the energy used in lighting systems with the light obtained on the ground as an essential measure of performance. ‘When cost is factored in, modern HID sources are still hard to beat’ says Harding. ‘Most LED lanterns, even the most efficient ones, are still generally more expensive than their HID counterparts, although we may now be turning the corner, with LEDs becoming the most cost-effective and energy-efficient choice for outdoor lighting.’
The Woodhouse fittings installed as part of London’s Exhibition Road public realm project (AJ Specification 03.2010 and AJ 08.03.12) are an integral part of Dixon Jones’ minimalist design strategy. Another lighting specialist, iGuzzini, is making the most of LED technology to develop discreet luminaires, such as Lun-up and the new Jean Michel Wilmotte-designed Linealuce compact and mini, which combine powerful lighting effects with low energy use.
Arup Lighting specified saturated red LEDs to light the ArcelorMittal Orbit at the London 2012 Olympic Park, designed by Anish Kapoor and Cecil Balmond with Kathryn Finlay Architects. Using Radiance lighting software, this strategy, which Arup Lighting Director Florence Lam calls ‘dark light’, emphasises the Orbit’s distinctive red paint finish and maximises visual impact while using less energy than white light, minimising spillage and sky glow. LEDs do not emit UV light, which would disturb local wild-life such as moths and bats.