"I was astonished,” wrote the German diarist Karl Philipp Moritz in 1782, “at the admirable manner in which the streets are lighted up, compared to which our streets in Berlin make a most miserable show.”
His astonishment was common among foreigners visiting London at the end of the 18th century, by which time many streets in the city were lit by oil-lamps. Standing in his breeches, blinking up at the lights above his head, Moritz couldn’t have imagined the incalculable benefits, both economic and social, that lighting up the night would bring to the developed world. Where there’s light there’s less crime, fewer accidents and more incentive to stay out working or spending money – 24 hour economies leave daylight ones in the dust.
But setting the night ablaze has come at a cost, too: London children, for instance, can no longer learn constellations by tilting their heads skywards. Exposure to light at night has been shown to have an adverse effect on sleep, alertness and melatonin levels. It confuses animals, interrupts ecosystems and generally compounds the disruptive effect of urbanisation on the environment. And while lights keep the economy whirring after dark, they’re an enormous drain on electricity.
On average, forty percent of a city’s energy bill goes on street lamps, a large proportion of which is spent lighting deserted streets with bulbs that use most of their wattage on heat rather than light. Billions are wasted globally every year.
But the days of light pollution and hopeless inefficiency may soon be behind us, thanks to the ingenuity of a trio of scientists from Japan. Last year, Isamu Akasaki, Hiroshi Amano and Shuji Nakamura won the Nobel Prize for inventing the blue LED, a tiny light that’s already making a big difference to the way our cities and buildings look after dark. The invention means a full range of coloured LEDs can now be blended to produce the coveted white LED light – a clean, clear beam compared to the garish orange of sodium street-lighting. Viewed from a plane, an LED-lit city looks sharper and better defined than one lit by electric bulbs.
Upward glare is reduced, and there’s none of the smudgy orange halo you get above a city lit with incandescent bulbs. Satellite pictures of Berlin at night show the difference: the west side, lit by LEDs, glows cool blue; the less affluent east, lit by gas bulbs, sears the sky, a hot mess of wasted energy. The invention of the blue LED marked the beginning of what urban planning expert Davina Jackson calls “the age of electroluminescence”.
In her new book, Superlux, she looks back at the first ten years of LED light in cities. She charts how buildings have been transformed from inefficient, light-polluting beacons to clean, high-concept aesthetic assets to urban space.
“LEDs allow cities to be lit with dynamic multicoloured light at night as well as white light,” says Jackson. “Lighting before this has been incredibly hot – flames, oil lamps, gas and then hot electric lamps. Now we have what I call cities of cool light, where you can actually touch the light sources.”
Urban centres the world over are clamouring to get in on the efficient action. LA, New York and Phoenix have in recent years begun converting old sodium- and mercury-based lamps to LED. And after a successful trial of LED lamps in London, TfL has pledged to convert 35,000 of the 52,000 streetlights on its network to LED by next year. Meeting this target will generate annual savings of £1.85m and cut CO2 emissions by 9,700 tonnes per year.
LEDs are also easier to direct, so you can point them down at the street where the light is needed, rather than having the light cascading all around. “To reduce light pollution the first thing to do is to not have light where you don’t want it,” says Jackson, “which requires more control over when lights are turned on, how wide the beams go, and where they’re pointing.
It’s also useful to shield the source of light, so it doesn’t go where it’s not wanted. Don’t go around putting search lights and lasers into the sky 20th Century Fox-style like they do in Hong Kong.”
The ability to accurately aim LED lights has opened up possibilities for architects looking to make an impression with eye-popping designs. The pages of SuperLux are filled with pictures of futuristic buildings lit with pinpoint beams in visages that wouldn’t have been possible twenty years ago. Other technologies, including the ability to 3D map the exterior of buildings and project site-specific projections onto them, are also transforming cities.
“At the moment we’re getting a convergence of different kinds of what I call ‘city screens’, says Jackson. “You can build screens into the internal fabric of a building, like the Dexia tower in Brussels. And you’ve got other technologies for lighting the whole exterior walls of buildings, thanks to developments in projection technology.”
The new technology hasn’t, however, been without its detractors. Some scientists have linked over-exposure to LED light to blindness, and, more recently, cancer (LED streetlamps emit light at wavelengths which studies have linked to depleted melatonin levels; some think depleted melatonin can cause cancer).
Defenders of LEDs say these problems can be mitigated by bulbs’ smart functionality: unlike sodium bulbs, they can be easily dimmed, so when there’s a lot of moonlight for example, the light from LEDs can be turned down, thus reducing exposure. Even if health concerns prove exaggerated – as is likely – there is sure to be a painful period of adjustment as people get used to the new light. Last year the New York Times reported Brooklyn residents were unhappy with the ghostly glow of the new LEDs: “It’s like the Night of the Living Dead,” said one.
It’s safe to say these are just blips. In the majority of places LEDs have been installed, residents have been positive about the change or haven’t noticed them at all. And anyway, it’s not like those New Yorkers have any choice to but to get used to them: within a year all 250,000 of the city’s lights will be LEDs.
The age of hot electric lights lasted 50 years. The cleaner, greener age of electroluminescence looks certain to last even longer. Thanks to the LEDs, the future of urban lighting design isn’t just bright – it’s dazzling.
Superlux by Davina Jackson, published by Thames and Hudson, is out now