© William Pryce

More than just a façade

The London headquarters of the Reiss fashion label is clothed in a floating curtain of light.

Both the collection and the Reiss flagship store are unusually striking. With its out-of-the-ordinary fashions, the company underlines the uniqueness of the people who wear its designs. But it also displays its own individuality: its headquarters in the City of London is wrapped in an extravagant façade, which reflects the label’s many facets and its philosophy, as well as fulfilling practical functions.

The project competition made clear specifications. The façade was meant to be eye-catching and indicate that fashion is created and sold in the building behind it. The aim was to achieve optical unity between the various areas such as salesrooms, offices, cutting rooms and design studios, as well as the penthouse apartment on the top floor. At the same time, the façade was intended to meet demands for modern building management and create a pleasant climate inside the building.

Fashionistas strolling down London’s Oxford Street walk straight towards the building in Barrett Street. It is noticeable from far off because it glitters and shines in the sunlight, creating a gigantic bar code effect, then suddenly takes on a completely different appearance when the light changes. At night, this impression is reinforced. Then it appears as if the building were wrapped in liquid light that imitates the folds of an enormous silk curtain.

British architects Squire and Partners came up with the idea for this opaque but dynamic light-transmitting curtain. To create shifting effects, the translucent elements of the curtain had to be machined. Vertical routing to different depths combined with matte and polished surfaces makes sure the light is refracted in a multitude of ways. The changing incidence of light in the course of the day supports this effect. The façade material for this purpose had to be light-transmitting and stable. “At the start of the project, all that was clear was that the building was to be surrounded by a curtain of light,” reports Thomas Ries who was responsible for the project at Evonik. “The decision in favor of the material was only made once the project was underway.”

At the start of the project, all that was clear was that the building was to be surrounded by a curtain of light.

Thomas Ries
Project Manager, Evonik

Idiosyncratic curtain

British architects Squire and Partners came up with the idea for this opaque but dynamic light-transmitting curtain. To create shifting effects, the translucent elements of the curtain had to be machined. Vertical routing to different depths combined with matte and polished surfaces makes sure the light is refracted in a multitude of ways. The changing incidence of light in the course of the day supports this effect. The façade material for this purpose had to be light-transmitting and stable. “At the start of the project, all that was clear was that the building was to be surrounded by a curtain of light,” reports Thomas Ries who was responsible for the project at Evonik. “The decision in favor of the material was only made once the project was underway.”

Glass was ruled out right at the beginning because it is too heavy and unstable for this project. In their search for the right material, Squire and Partners came across PLEXIGLAS®. “They decided to use block elements,” Ries
reports. “These are ideal for the project because they can be machined in different ways and thus enable variable material thickness without losing their stability.” The material’s UV resistance also ensures that the panels do not yellow or become fragile. The light transmission and effect of the façade are preserved on a durable basis.

Profiles help to ring the changes

Seventy-three PLEXIGLAS® blocks had to be cut to size to completely clad the five-storey building. The initial sizes of the PLEXIGLAS® blocks were 5 by 2 and 3.8 by 1.8 meters at a material thickness of 50 mm. Few companies can machine such large workpieces. With the neces­sary equipment, like a special CNC mil­l­­­ing cutter, and a large dose of experience, Heinz Fritz Kunststoffbearbeitung converted the blocks to the required shape and size, and profiled them to different depths. The installation length is between 4.2 and 3.4 meters, and the width is between 1.6 and 1.4 meters. The thinnest sections were machined down to a residual thickness of 20 mm. The routing depths vary between 10 and 30 millimeters.

Polished or matt

Before and after routing, the blocks were evenly heated in an annealing oven to remove any stresses from the material. This equips it in the best possible way for durable outdoor weathering and the related stresses. To reinforce the lighting effects, certain parts of the panels were polished or dulled. Depending on the way light falls on the façade, viewers see a constantly shifting play of light because the rays are refracted differently by the routing patterns. The heterogeneous surface treatment also provides pleasant glare-free light, which is especially important for work in rooms such as studios and offices behind the façade. These also require a pleasant climate with acceptable temperatures.

Fascination combined with function

Especially the rooms facing south have to be kept cool by the façade. Although PLEXIGLAS® intercepts a portion of solar heat, the architects decided to back up this cooling effect. To do so, they installed the façade at an accessible distance from the wall of the building, leaving room for air to circulate and maintenance work to be carried out. The PLEXIGLAS® panels are thus spaced 40mm apart and about 60 cm from the wall of the building. Each individual panel is mounted on two T-shaped steel consoles and on vertical stainless steel rods that are fastened to the façade structure at individual points concealed by routed recesses. Since wind can easily be trapped between the façade and the building, the connections with the façade structure are slidable. The spacing of the panels ensures that wind loads are dissipated. “That works even if the panels expand longitudinally due to heat,” Ries explains. “Special attention was paid to fastening the sheets to the structure so that differences in linear thermal expansion and extreme wind loads can be durably dissipated.”

A glowing face at night

The almost invisible fastening makes the façade appear to float independently of the building. It is an eye-catcher that can be seen from afar, not just during the day, when sunlight is refracted in the panel profiles, but also at night. “LED strips are mounted behind the PLEXIGLAS® blocks,” Ries explains. “They can be separately controlled and are programmed to make the façade shine in a cold white light at the bottom, that becomes warmer on the way up.” The optical brilliance of PLEXIGLAS® causes the curtain of light in the City of London to ripple and shimmer, and gives the Reiss flagship an unusually striking outfit.