A small reception building on an unremarkable industrial estate has a visual surprise up its sleeve. Its upper storey is covered with a so-called retro-reflective foil, that looks black from all directions except from the angle of the light shining onto it.

NL Architects were assigned to refurbish an existing gatehouse, and have done so in style. The building is the main entrance of the IPKW estate in the Dutch town of Arnhem. It looks like a shiny black box suspended above a delicate layer of glass. This is an interesting architectural contrast, made powerful by angular lines and the application of a high-tech retro-reflective material.

The focus is on the tightly constructed box that is the upper floor. The retro-reflective or ‘cataphotic’ film is a prismatic Scotchlite film made by 3M. This means that, unlike a reflective film, reflected light is emitted at the same angle as it is projected onto the film. The flexible black foil has a doubly refractive layer (200 µm) applied to it, in front of a highly reflective backing. This is the same principle use in some safety clothing and road signs. The sheeting is adhesive so it’s simply stuck onto the façade.

The effect is particularly visible at night: an approaching lorry would see the building light up ahead, but that light wouldn’t trouble people or vehicles in the surroundings. And why have a whole storey of a building clothed in darkness? The answer is simple: the building contains a data warehouse that needs neither daylight nor a view.

The black box rests upon a lobby made of slender steel and single layer, highly see-through glass. Gatekeepers are kept warm behind a second layer of glass, so the public part of the lobby is, technically, cavity space. The all-round glass allows the gatekeepers an almost panoptic view, which is enhanced by raising them on a slight podium in the middle of the lobby. This in turn means a higher ceiling is needed, which is achieved by suspending a thin fabric close to the underside of the upper floor. That fabric is top-lit, so the gatekeepers are bathed in a halo of light.

Light clearly plays an exceptionally important role in NL Architects’ work here. It serves as an example of how smart technology, architectural insight and clean design can really transform a simple, unassuming shack into a shining little gem of a building.

Images: Jeroen Musch.