Night Vision

During the day, 10 Exchange Square blends in seamlessly with most new office developments in London’s financial district. But at night, the building is transformed. “We have finally achieved our vision of glowing lines of steel, using a luminaire that can’t be seen in daylight,” says Tapio Rosenius, senior designer at Maurice Brill Lighting Design – who, together with architects Skidmore Owings & Merrill, has been responsible for the lighting scheme.

The 14,000 m2 office is the latest addition to British Land’s Broadgate development. The idea behind it was to create a strong entrance and an interesting night-time impression of the building – key to achieving this was the integration of a linear lighting detail within the 80 mm-wide stainless steel spandrel channels running along the curving south facade. Multiple point LED sources were chosen for their reaction with the superbrushed steel – the entire facade lighting consumes just 3 kW.

The subtle nature of the scheme belies the work that has gone in to it. It took over six months and five full-scale mock-ups to develop the flush, linear detail. “British Land wanted us to prove that it would work,” explains Rosenius. “A lot of people think LEDs are fit-and-forget technology, but that isn’t the case. We had to address the maintenance issues at the outset”. Working closely with the facade designers and electrical contractors, they developed a fixing system to allow for thermal movement of the facade and ensure minimal interference with the lighting.

Another key visual element is the walls flanking the entrance steps which have varying curvatures and vertical tilts. These are lit with a series of custom-modified 20 W CDT-TC recessed uplights. LED lighting with a cooler colour is integrated into the handrails to create a brighter route down the steps. Inside the building, the external walls are mirrored inside the entrance lobby. The wall lighting here forms a key part of the exterior lighting strategy, enhancing the transparency of the curtain wall, which appears silhouetted against the cast glass walls.