A network of light

Published on 26/05/2022

Beat Grossniklaus leans over one of the 10000 or so panels that will soon adorn the roof of the Novartis Pavillon. The experienced foreman of the Basel-based technology company iart screws one of the rhomboid panels onto a specially developed steel framework that mimics the idiosyncratic shape of the Pavillon.

Each individual panel, as well as the steel structure on which the individual elements are attached, is tailored to the shape of the curved roof. In future, it will not only guarantee that the building is supplied with electricity, but will also communicate with the city. The panels have a dual function: They produce electricity, and the LED lights screwed onto each of them will be used for discreet light displays.

“The panels are an innovation that iart developed especially for the Novartis Pavillon,” says Grossniklaus, who is carrying out the work with his colleagues in a spacious warehouse on Campus. “There is no such media façade anywhere else in the world – it’s actually an experiment.”

Media mesh

The network, which iart refers to as a media mesh, consists of a complex load-bearing steel structure, organic photovoltaic (OPV) panels and LED units that only consume as much electricity as the solar panels produce – a so-called zero-energy media façade.

The panels are integrated into the steel structure, which has been specially developed for this project. The structure holds the elements in place at a distance of around 40 centimeters from the actual sheet metal roof, which also serves as a reflective surface for the artificial light. The construction integrates the necessary cabling through which electricity and signals flow, connecting all the LEDs so they can be used by artists for future lighting animations.

Reto Weljatschek, the industrial designer responsible for the project at iart, designed the media façade: “At first, it was about fundamental questions: How many of the freely shapeable OPV elements should be accommodated on each façade section, or how many LEDs are needed to be able to display text in the lower section? And what are the best proportions for the 480 large rhombus elements that currently carry a total of over 10000 OPV cells?”

Weljatschek developed five different rhombic shapes for different positions on the curved building shell. They in turn consist of 102 different tubular elements and are held together by 30 different node types. All of these elements were bolted, so that they could be handled during flexible pre-assembly, assembly and operation.

The ultimately homogeneous second skin of the Pavillon thus consists of numerous custom-fit individual parts, which were specially developed by iart. The load-bearing steel frame, says Weljatschek, consists of “a whole family of mesh elements.”

For installation on the façade, the larger mesh elements, which are made up of 16 panels each, are pre-assembled, tested and then hoisted onto the roof by crane, where they are mounted by a team of specialists.

When designing the panels, the iart development team drew inspiration from cell structures: “The idea was to see the Pavillon as an organism, which should be reflected both in its shape and in the light displays that are shown there later,” explains Christian Reimann, who is managing the project on behalf of iart.

Another important innovation are the solar panels, which are not based on traditional silicon technology, but on organic photovoltaics. With this technology, which was developed and produced by French technology firm Asca, panels can be designed flexibly and, with regard to their shape, almost freely.

By choosing organic solar panels, iart was also able to operate in a more environmentally friendly manner, as traditional silicon panels have to be produced in a very energy-intensive manner.

“The manufacture of inorganic solar cells involves an enormous amount of gray energy,” says Michael Stucki from iart, who developed the electronics for the media façade. “This can be significantly reduced with the use of organic photovoltaics.”

Organic photovoltaic technology is based on carbon compounds instead of silicon. The term “organic” refers to organic chemistry, which is based on carbon molecules.

One disadvantage of OPV panels, however, is their comparatively low efficiency, especially when exposed to strong sunlight. Under weak lighting conditions, on the other hand, OPV panels are more efficient than conventional panels.

The main advantage of the organic panels is their adaptability due to the so-called thin-film printing technology. “The OPV panels are printed onto a thin film in France and then cut to size in Germany,” says Stucki. “This means we can be relatively free in selecting the shape and size of the individual panels.”

Because the thin OPV layer must not come into contact with water or air under any circumstances, the OPV film is bonded between two diamond-shaped polycarbonate sheets in a sandwich configuration that provides an airtight seal.

The individual panels are then delivered directly to the Novartis Campus to iart’s temporary manufacturing hall, where the LEDs are attached to the cells using a bayonet connector. This procedure also simplifies the subsequent replacement of the lights.

“The panels are bendable to a certain degree,” says Grossniklaus as he demonstrates the elasticity of a panel. “This makes it possible to adjust the shape optimally when the panels are screwed into the metal mesh.”

This is important. Because of daily and seasonal temperature differences, as well as the movement of the various materials on the façade, the panel construction also had to be flexible. “With the construction of 16 elements and the special design of the mesh, we were able to ensure this,” says Weljatschek.

However, there are more innovations of the media façade, including the light itself. The individual panels are semi-transparent and have a bluish color. Due to the double-sided use of the LEDs, they not only emit light away from the façade, but also onto the sheet metal façade behind it.

“This type of lighting generates a specific translucency that enhances the organic character of the building and gives the façade a kind of membrane effect,” explains Reimann from the project management team.

Furthermore, to minimize light pollution, the LEDs only operate with a slight contrast to the existing light. “The intensity of the luminosity is varied and dynamically adapted to the surrounding lighting conditions,” explains Reimann.

The highly innovative façade of the Novartis Pavillon, for which iart received a Media Architecture Biennale Award 2020, thus contributes to environmental protection not only in terms of energy efficiency, but also by reducing light emissions.

“Of course, it would be great for us to see a similar technology being used on other buildings in future to generate the impressive lighting effects in an environmentally friendly and sustainable way,” says Reimann.