The photos above may appear to show a sunlit sky – but they don’t. What they show is a brand new type of artificial skylight called CoeLux that, for the first time, reproduces the physical phenomenon that makes the sky appear blue.

CoeLux won the prestigious Light Source Innovation of the Year trophy at the Lux Awards 2014, and was the standout attraction at LuxLive, drawing queues of visitors to a low-ceilinged stand in the middle of a windowless exhibition hall, where they could look up to see… the sky.

CoeLux’s ‘sky’ is a convincing azure, and the ‘sun’ looks a lot like the real thing – even giving the impression of being distant. The overall effect is that of sunlight pouring into, and bringing life to, a small room.

If you spent more than five minutes on the CoeLux stand, you’d begin to hear the same questions over and over: What void space do you need? Does the ‘sun’ move? What’s the energy consumption? In essence: what’s the catch? It’s human nature when faced with technology this impressive.

The secret is a clear polymer layer containing titanium dioxide nanoparticles that produce Rayleigh scattering – the same process that occurs in the atmosphere, splitting up different wavelengths of light to make the sky appear blue. CoeLux also creates an illusion of depth to make the light source appear far away, rather than just a metre or so above you – but the makers are tight-lipped about exactly how that’s done.

‘It’s not a lamp. It’s not a luminaire. It’s something else’, says CoeLux’s inventor, Italian scientist Dr Paolo Di Trapani.

CoeLux inventor Paolo di Trapani presents the technology at LuxLive

Di Trapani delivered an impassioned presentation at LuxLive about sunlight and colour, pointing out subtle gradations of blacks in a Mark Rothko abstract, or specific brushstrokes in a Van Gogh self-portrait. He barely even mentioned his product, but that didn’t seem to bother attendees, who broke into spontaneous applause as his presentation reached its crescendo.

‘I haven’t stopped talking all day,’ said Kevin Andrews of Ideaworks, the company that is commercialising CoeLux in the UK. Not only was there a steady stream of people to the stand, but once people got there, they were in no hurry to leave.

Ideaworks, which specialises in technology for high-end interiors in the hospitality and residential markets, is hoping to bring (artificial) sunlight to underground spaces that until now have lacked daylight – gyms, for instance, and in London, the new breed of ‘iceberg homes’ with cavernous basements.

Andrews makes no bones that this is ‘version one’, and the technology has further to go. No, the light source doesn’t move… yet. No, the colour temperature isn’t dynamic… yet. The skylight consumes 340W, but that will come down as LEDs improve.

CoeLux is at the beginning of its commercial journey, and if you want to install one, you’ll have to dig deep – in every sense. It requires a one-metre ceiling recess, and will set you back £40,000 ($60,700) from the factory gate, and another £3,000 to £5,000 ($4,500 to $7,500) for shipping and specialist installation.

Still, if the interest at LuxLive is anything to go by, the future of CoeLux is very bright. And very blue.

  • (and a half)  It’s a much overused word, but CoeLux really is awesome. Still, we’re holding back that last half star to see what they do with version 2.0…