Lighting Efficiency
LEDs City’s towering example
One ‘early adopter’ of LED office lighting is Tower 42 – formerly the NatWest Tower – in the City of London (above and left). This iconic landmark has recently completed a major investment and refurbishment of its level 12 office space, which is among the first in the UK to use all solid-state lighting. Although LEDs are not yet as efficient as the best T5 technology, they are, nevertheless, delivering savings against the previous design. The lighting system is controlled using a digital
addressable lighting interface (DALI) protocol so that all luminaires are individually addressable. Multi-sensors are used in the spaces to provide both dimming in relation to daylight levels and occupancy detection with corridor linking. Occupants can also control their own lighting using infrared remote control units.
in the productivity of the staff affected, as well as improvements to their alertness and comfort. An initial study carried out in 2006 demonstrated that work performance was improved, fatigue was reduced and greater alertness noted. The use of high correlated colour temperature lighting, dynamically mixing it with warmer lighting to create variation through the working day to stimulate interest, can be further developed. As scientists research learning, they are finding that even the most basic changes (such as lighting) can improve education environments. According to a recent study by Professor Michael Schulte-Markwort, director of the Clinic for Child and Youth Psychology at the University Hospital in Hamburg- Eppendorf, dynamic lighting systems can improve the reading speed of children by 35 per cent, and reduce reading comprehension errors by 45 per cent. ‘The drop of 45 per cent for the group working under dynamic lighting shows that with the right light in the classroom it is possible to increase pupils’ attention span and concentration significantly,’ said Schulte- Markwort. Such lighting has also been successfully applied in hospitals to the benefit of nurses working the night shift.
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Clearly this ‘blue sky’ approach to lighting, with or
without the dynamic element, is more effective in its purpose than more conventional solutions. The worry, though, lies in whether such innovation will continue if the only objective being pursued is energy reduction. If we can continue to build our understanding of light in the workplace and so improve the way it is delivered, then perhaps we can work fewer hours with the same levels of productivity, thereby also reducing our demands on other energy-intensive systems such as IT, air conditioning and heating. And if industry succeeds in making artificial light emulate daylight, then we must design the next generation of buildings to use as much natural light as possible. Artificial lighting will still be needed but a good control system will integrate it with daylight, so that energy use is minimised while still retaining the qualities of both natural and artificial light and the benefits they deliver. Perhaps this answers the old art versus science debate – lighting is a science, but with creative tendencies. l
John Aston is green marketing manager for Philips Lighting UK
As the Building
Regulations develop there is the danger that energy-saving measures will lead to prescriptive rules
May 2010 CIBSE Journal
41
Redshift Photography
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