CoeLux skylight brings "sunlight" to windowless spaces


June 12, 2014

A complex optical system creates an almost 3D sensation of distance and space between the faux sky and the sun

A complex optical system creates an almost 3D sensation of distance and space between the faux sky and the sun

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For residents living in the north, where sunlight can be a rare commodity during the winter, a psychological condition known as Seasonal Affective Disorder is a very real problem. Light therapy is one way to shake off the winter blues, and although artificial lighting solutions do exist, they are generally available as simple variations on traditional desk lamps. An Italian designer has developed CoeLux, a unique system that delivers artificial light through an intelligent false skylight.

Professor Paolo Di Trapani of Italy’s University of Insubria spent over 10 years working on a sunlight emulation device called the CoeLux system. The concept aims to recreate artificial light as it exists beyond the walls and ceilings of enclosed spaces, and bring realistic illumination into spaces like subway stations, museums, or spaces where people are removed from the feeling of well-being that natural sunlight delivers.

The CoeLux skylight system utilizes three key elements to emulate natural lighting. Using proprietary technology, Di Trapani has incorporated select LED lighting to closely resemble natural light and the sun in the sky. The team then developed a complex optical system which mimics the sun and its rays using nano-structured materials to recreate in just a few millimeters the Rayleigh scattering process that occurs in the atmosphere. But making a ceiling blue with a false sun does not a realistic artificial light source make.

According to Di Trapani, in order to achieve a 3D effect and emulate natural sunlight, the team had to meet a number of design specific challenges. First his team had to develop a photorealistic rendering engine that was capable of accurately simulating sky and sunlight when working with select materials.

“The objective included further developments of the existing Maxwell Render software functionality to include light scattering properties, light polarization effects, custom spectrum data (through spectrum curves or raw data) and light spectrum measurements, by including a virtual spectrophotometer," explains the inventor.

In the new rendering engine, new user interfaces were developed to allow easier interaction. From lighting experts to designers to physicists, the new engine and interface are designed to assist the user in configuring the spectrum profile for their individual purposes.

But the CoeLux not only delivers faux daylight to enclosed spaces, it can also be programmed to emulate three different geographic lighting scenarios, such as northern Europe for example, where the light runs at a lower angle relative to the horizon than at the equator.

The CoeLux 30 system offers a wall mounted "window" that produces a warm, grazing light typically found in northern regions like Scandinavia. By contrast, the CoeLux 60 delivers an equatorial, vertical type light that projects cooler tones and more dramatic shadows. And in the middle is the CoeLux 45 skylight which presents a 45 degree light designed to offer a balance of light and shadow for those Mediterranean residents residing around the 45th parallel.

Because of the psychological healing properties and well being benefits associated with natural lighting, the designer foresees the CoeLux system having applications in healthcare, senior’s facilities, hospitality spaces, retail, residential and even transport. The entire system is incorporated into an elaborate false ceiling is only a few millimeters thick but still manages to very closely resemble an actual skylight. CoeLux is able to recreate the experience of sun and sky and bring the outside world inside.

Funded by the European Union and featured by the European Commission at the 2014 Innovation Convention in Brussels, the CoeLux system was selected as one of twelve upcoming innovative technologies in the EU. A CoeLux installation can be seen in Venice, Italy, at the 2014 Biennale Architettura.

A more detailed project summary of the CoeLux system can be viewed at the European Commission's CORDIS portal.

Source: CoeLux

About the Author
Angus MacKenzie Born on the cold, barren Canadian plains of Calgary, Alberta, Angus MacKenzie couldn’t decide between marketing, automotives or an entrepreneurial path - so he chose all three. With an education in automotives and marketing, Angus has rebuilt the carburetor on his 1963 Rambler Ambassador twice, gotten a speeding ticket in an F430 once, and driven & photographed everything from Lamborghinis to Maseratis to various German and Asian designs. When not writing, Angus has for the past six years been Editor-in-Chief for elemente, an internationally recognized architecture/design magazine. All articles by Angus MacKenzie

From what I've read, seasonal affective disorder (SAD) appears from vitamin d deficiency. (The lower angle of the sun means photons pass through more ozone which absorbs more UV light.) This has an effect on several key endocrines. Unless this light source also provides UV light, it's not going to have any effect on SAD. I couldn't find any mention of UV light in the CoeLux website. I also couldn't find any mention of SAD in the CoeLux website but there are numerous news sites that use it. Was the term added by journalists or is this product actually created to provide UV light and reduce SAD?

Jim Bruin

I think that is really cool.

With the greater appeal, perhaps the cost will be lower since the cost is spread out with amount of ones being made.


With this I can imagine living in Mars.


Not a single detail of how it's done, every one of the photo shopped renderings is not the actual environment. Recreated on every single site linked with this Google it yourself..

To see how the COELUX technology works, go to

COELUX COELUX® is a research project funded by the European Union under the 7th Framework Programme (FP7). The European Commission featured COELUX among twelve innovative technologies showcased at the 2014 Innovation Convention in Brussels in March. COELUX combines three key elements: the latest LED technology which reproduces the sunlight’s spectrum; a sophisticated optical system that creates the sensation of the distance between the sky and the sun; and nanostructured materials, only a few millimetres thick, which recreate the entire Rayleigh scattering process which occurs in the atmosphere. These elements are incorporated into a “high-tech window” system offering an enormous range of opportunities and design possibilities for indoor architectural spaces. COELUX is the result of collaboration between COELUX, owner of the lighting technology (IT),

Next Limit Technologies, owner of the photorealistic rendering engine Maxwell Render (ES) and Ekspobalta, responsible for COELUX large-scale installations worldwide (LT) and research partners Griffin Software Srl, (RO), Eidgenössische Technische Hochschule (CH), Bartenbach GmbH, Aldrans (AT) and Comonext Scpa (IT). For further information please visit

After 5 years still no factual evidence that the prototype actually works at a cost that is realistically affordable.

Bob Flint

Don't forget it has to also recreate that penetrating heat sensation. You get this from a strong long infra-red wave emitter. Heating particular ceramics or clay can achieve this.


Any announcement on turning this into a product?

Julien Couvreur
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