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I have often been told that Sweden has the world's highest suicide rate because of its seasonal darkness, with some regions having only a few hours of light on winter days.

Although the statistic isn't true - the nation actually ranks 30th in the suicide charts - it should come as no surprise that the canny Swedes want to make the most of the light they've got.

In April, Gothenburg-based company Parans launched a revolutionary system that transports natural daylight into areas of buildings that windows can't reach. The system has three components: SkyPorts, SunWires and Bj÷rk luminaires.

SunWires, only 25mm in diameter, are made from exible, fibre-optic cables, which are essentially different from reective systems such as Monodraught's mirror--nished aluminium Sunpipes, with diameters from 230mm to 1,500mm .

SkyPorts collect sunlight and are generally placed on roofs, although they can be fixed to a facade. The light is then transported through SunWires to semi-transparent acrylic Bj÷rk luminaries.

The brightness of the Bj÷rk luminaire depends on weather conditions and the SunWire's length. The system inevitably produces brighter lighting on sunny days, while the effect of passing clouds transfers instantly to interiors. The company's technical data states that light intensity decreases every metre by 4.6 per cent, with a maximum SunWire length of 15m. If there is 100,000 lux outdoors, a Bj÷rk luminaire with a 7m SunWire will provide 4,000 lux. Parans products come with a two-year warranty and are designed with a 30-year lifespan. (The case studies opposite show the products in action. ) The system can be turned on and off like conventional lights, but scientists have yet to find a way to store sunlight for later use (see ajplus. co. uk/ news 09.10.06). So why not install other renewable energy devices to power electric lights instead? The Parans system won't top up your tan - all UV and IR radiation is filtered out and no heat is transmitted - but there are other benefits. The company cites medical research to suggest that natural light ameliorates Seasonal Affective Disorder (SAD) and even creates a more alert workforce.

'When we open our eyes in the morning the production of melatonin - the hormone that induces sleep - is blocked and we feel awake, ' says Rikard Eduards of Parans. 'This blockage reaches a maximum when the light's wavelength is 460nm - a wavelength plentiful in daylight, but scarce in electrical lamps.'

Parans' ecologically sound lighting system consumes almost no energy; a single SkyPort uses less than one euro of electricity per year. If integrated at the design stage, atria or lightshafts can be avoided to generate more usable oorspace (could this affect office legislation about window distances? ). The system can also be fitted into existing buildings with minimal disruption. With such green credentials, it surely can't be long until David Cameron puts one on his roof.

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