Lighting designers at Licht Kunst Licht have created a unique way to bring a touch of the outdoors to a basement cafeteria, harnessing the power of “artificial daylighting”.

Few people would suggest a basement without daylight as an ideal location for a cafeteria. However, Licht Kunst Licht, alongside Frankfurt-based architectural firm ttsp hwp seidel, has created a biologically effective “artificial daylighting” system that transports employees of a multinational banking and financial company in Düsseldorf to the banks of the Rhine.

The canteen in the financial corporation’s basement was typical for the time of its construction. Yet while the red granite façade of the building, designed by HPP Architekten in the 1970s, still emanates a timeless elegance, the windowless canteen had become visibly outdated. Coupled with the inadequate technology, illumination and functionality, the space had a distinct lack of daylight and flair, which affected the overall quality of the space. A renovation was therefore badly needed.

This renovation saw the architecture and lighting of the staff restaurant and associated kitchen optimised; the crooked and inefficiently used dining area and kitchen plan layouts were fundamentally simplified, and free flowing, interlocking functional areas were established. As a result, the amount of seats could be increased from 150 to 200.

An essential design task in the renovation of the 465sqm space was the introduction of an additional daylight component and a reference to the outside world. Given the canteen’s basement location, this task proved difficult for the architects, and for the project lighting designers, Licht Kunst Licht.

Isabel Sternkopf, lighting designer and project manager from Licht Kunst Licht, explained: “After getting involved in this project, the architect and client gave us an initial briefing that was focused on artificial lighting only, but in the course of the project it turned out that an additional daylight entry was required by the local district government. As a result our lighting design suddenly focused on generating this subsequent daylight input.”

However, comprehensive studies undertaken by the German lighting design firm demonstrated that, with the small window openings that could be established, the daylight intake would be minimal, and the positive effects of natural light and a view to the exterior would be imperceptible.

“We performed calculations and realised that there is no possibility to provide sufficient daylight,” Sternkopf continued. “So we started a discussion with the local district government and tried to convince them that an artificial daylighting concept adds more value to the users than small basement windows.”

Sternkopf and her team argued that the added value for the user could only be established through artificial light that simulates natural light with daytime-related and annual variations, dynamic changes in light colour, light direction and intensity, while simultaneously supporting the circadian rhythm of the occupant.

As a result, Licht Kunst Licht developed the idea of a 22-metre-long, floor-to-ceiling artificial panorama window. Extending across the entire canteen rear wall, it compensates for the lack of daylight by establishing a mimicked relation with the exterior.

Displaying images from artist Stephan Kaluza’s series The Rhine Project, in which he followed the entire 1,233 kilometres of the river Rhine, documenting his voyage with a series of camera shots taken every few minutes, the window was intended to show a view of the Rhine that one might see from a room at ground level. The photograph is printed on a folded plasterboard, which is applied to an existing concrete wall. A floor-to-ceiling glazed window is located in front of the photograph, protecting it from dust and damage, while enhancing the impression of a window to the outside.

Illuminated by iGuzzini’s Linealuce Compact fixtures concealed in the ceiling behind the glazing, the lighting starts at a warm 2,700K in the morning, gradually changing to a cool 6,000K around noon, before returning to the warmer hues in the evening. Similar floor-mounted RGBW-LED profiles, mounted behind the glass wall, allow for an upward grazing light effect on the backdrop, emphasising and intensifying the texture. These fixtures create light colours in orange hues for the scenes during sunrise and sunset.

However, while the panorama window is an impressive, innovative solution to the lack of natural daylight, Sternkopf had to work to convince the district government that the window had no harmful effects on the health of the employees. “We had to prepare countless presentations and meetings, and at the end we needed to provide a medical certificate that confirms that our artificial lighting concept was not harmful to the users,” she said. “We did a lot of technical and scientific research to find out how the artificial lighting could appear as natural as possible, and we had an expert of occupational health and safety, as well as an occupational physician consultant involved in the project.”

Further to the introduction of more natural light, the architects wanted the new-look space to feel “more like a restaurant than a canteen,” according to ttsp hwp seidel architect and project manager Tanja Nopens, and the new lighting scheme was designed to support and respect this impression. “An intelligent lighting control system allowed us to create differentiated lighting scenes to avoid the homogenous and uniform lighting atmosphere often experienced in canteens,” Sternkopf explained.

Functionally, the space is organised into four ‘zones’, each with distinct lighting approaches, ceiling heights and furniture. The largest area, with long wooden benches under an open white ceiling, is the central meeting point for larger groups to eat and exchange ideas. The wooden furniture designed for the project creates punctual warm accents that contrast with the black seating.

The focal point for visitors is the free-flow area with the food counter. Designed entirely in black, its ‘spaceship-like’ counters extend to the kitchen partition wall. Towards the exterior wall is a narrow zone with a group of four-person tables, which is surrounded by building columns and a lower ceiling, making it suitable for quiet and more confidential conversations.

The illumination for these different zones is, as intended, more akin to a restaurant than a canteen: warm and inviting. Some of the seating areas are accentuated by pendant luminaires, courtesy of XAL and Artek, while the large flex-use seating zones at the centre of the dining room are more evenly illuminated with Soraa spots embedded into a custom-designed, grid-like structure. iGuzzini’s Laser Blade High Contrast provides vibrant accent illumination above the buffet stations, complemented by the Italian manufacturer’s discreet Pinhole Adjustable Round recessed luminaires in the circulation areas.

The colour temperature of the circulation lighting and the illumination of the adjacent open kitchen area is also variable, and is controlled in sync with the panorama window wall. All luminaires are programmed to create an atmosphere similar to daylight, with gentle light transitions intended to create the impression that occupants are in a room illuminated primarily with daylight and only supplemental electrical light. “Together with the architect we have developed a concept that makes the room appear spacious, friendly and inviting,” Sternkopf said.

While the project may have presented some difficulties to Sternkopf and her team, she feels that any problems that they encountered only helped lead them to the end result. “Sometimes I still wonder what twists the project has taken over time,” she said. “In the end, we can even be grateful that the district government demanded the entry of daylight, and allowed it to be interpreted through the artificial panorama window, as it enabled us to pursue this innovative approach.

“There is no study or hormone examination yet, but there is feedback from the client that the occupancy rate of the canteen has increased significantly. Of course, this is not only due to the lighting, but the client also mentioned that the seats at the window are always occupied first, which is an indication of the successful implementation of the concept.”

Since completion, Sternkopf and Licht Kunst Licht have received a lot of positive feedback, with Sternkopf going on to present the project, and particularly its use of ‘artificial daylighting’, at last November’s IALD Enlighten Europe conference in Barcelona. “Many people were surprised by the result, and that we put so much effort into the project,” she said of her presentation.

“A lot of them were very interested in the topic of human centric lighting, especially because it is still relatively rare to work on such projects. Even though this was only a small project, it shows what added value a human centric lighting concept could generate for users.”

www.lichtkunstlicht.com