Lighting special Street illumination
T
wo years ago, at its concept showcase, Sense and Simplicity exhibition in Moscow, Philips unveiled its Light Blossom solar/wind-powered amenity light. Its
photovoltaic-panel petals slowly open in response to sunlight, moving heliotropically like a sunfl ower to optimise power. On cloudy, breezy days, the petals move to an upward, half-open position allowing them to catch the wind. The rotary movement is transferred to the built-in rotor and converted to energy. As dusk falls, the petals close and the LEDs on their underside and on the stem switch on. In standby mode, they glow at the minimum level needed for safety. A motion sensor registers when people pass by and racks up the light intensity. This was the vision of a street lighting future – not
only low energy but capable of feeding into the grid, and highly aesthetic. The designers were talking of it becoming a reality – subject to testing and modifi cation – in just a few years. It nevertheless seems poles apart from the present-day realities. Talk to most cash- strapped local authorities and their main concern is how to cope with basic upgrades, never mind lighting utopias.
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The use of solar/wind-powered lighting in the UK is currently restricted to applications such as footpaths, car parks and outlying bus shelters where light output is less critical, and for remote sites where the comparative cost of cabling makes them more economically viable. Because of our comparative lack of sunlight, the only way to get enough juice out of fi ttings is generally to combine solar and wind-powered elements. However, the street lighting landscape has seen some
major changes over the past fi ve years and, driven by the need to save energy and money, is set to undergo further radical improvements. ‘There has been a lot of investment through PFI
[private fi nance initiative] in street lighting in recent years and this has led to changes,’ says Alistair Scott, the new president of the Institution of Lighting Professionals (ILP, formerly the ILE). ‘Because contractors have been desperate to reduce
their costs and make as much profi t as possible, they’ve looked for innovative solutions for saving money. This has meant that white light is used a lot more widely – for instance, it is coupled with the introduction of electronic gear to give the ability to reduce lighting levels when usage is lowest.’
November 2010 CIBSE Journal 39
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