The life and works of St Botolph

At 500,000 sq ft, the St Botolph Building at 138 Houndsditch is one of the latest and largest office developments in the City of London’s EC3 insurance district. Lighting consultant Speirs + Major has created subtle and superbly controlled lighting to add a people-friendly ambience to this fast-paced working environment. Amanda Allen reports

Purpose-designed with City workers in mind, the St Botolph Building on the edge of London’s financial hub is built around the effective movement of its users. With speed of the essence in the financial world, every element of the building’s design aims to facilitate the circulation of people around the 500,000 sq ft building.

This includes the lighting scheme, designed by Speirs + Major, which guides workers from the shared entrances to their individual office receptions, illuminating key elements of the building along the way. “The internal space was very much built around the circulation of people around the St Botolph Building,” says Andrew Howis, associate director with Speirs + Major. “We therefore looked carefully at how we could improve the worker’s journey around it.”

The journey begins

People enter the building through revolving doors, which are highlighted with Erco metal halide downlights. Moving into a colonnade, the same Erco fittings were used but here they are customised with a half-frosted glass. “This means that the downlights provide a very soft wash that goes all the way to the top of the columns. Because the wash is very soft, you don’t get any of the scalloping you might normally get,” says Howis.

From here, people move into a split-level reception that was designed around the loading on two floors of the lifts. The high-tech lift system incorporates four different shafts with two independently moving cars in each shaft.

“For us, there were various issues with having a split-level reception,” explains Howis. “We felt that, for people intending to go upwards in a lift, it would be counter-intuitive to first go down escalators to get to the lower ground floor. We really had to look at how we would pull people down into that area.”

Customised cladding

Another issue Speirs + Major identified in the split-level reception was that some areas at the rear had a somewhat ‘depressed’ atmosphere. “Most of the space is double-height, if not triple-height, but at the back there are some single-height spaces and we had to consider those areas carefully,” says Howis.

The solution was to emphasise the vertical surfaces. Rather than simply wash the walls, the lighting design team decided to clad the entire reception in light and, in conjunction with the architect, developed a cladding system of fins with fully integrated lighting and textured detail panels for light to wash.

“It was very important for us to integrate the light seamlessly and to achieve consistency across the large number of fittings,” Andrew Howis, Speirs + Major

“We used 2,500 ACDC custom LED fittings incorporating Cree LEDs, and 8km of extrusion,” says Howis. “It was very important for us to integrate the lighting seamlessly and to achieve consistency across the large number of fittings. We wanted to make it integral to the fabric of the reception area so you don’t know where building ends and lighting begins.” While the finished solution appears quite simple in appearance, it was not without its challenges, and testing took several months. “It was quite an undertaking to actually try and match 2,500 white LEDs and we knew it was always going to be a challenge,” Howis recalls. “We went through a very substantial period of testing and experimenting with ACDC to achieve the finished result.”

The central atrium

The tone of the central atrium of the building is set by four huge glazed cores positioned around the perimeter, which contain the stairs and lifts. Here, the concern was that the lift structure would be too imposing and create a heavy presence in the atrium. To counteract this, glazed floors were introduced on the advice of the lighting design team. “Early in the design process we persuaded the architect and client to invest in glazed floors, which we uplit using a custom-designed integrated profile system from Zumtobel that uses high-efficiency T5s,” says Howis. “Because it’s such a big structure and there is a lot of metalwork, we felt it was necessary to maximise the lighting running through the atrium. We didn’t want this space to feel too heavy and we felt that there was a danger that the metalwork could really predominate and feel quite aggressive.”

The upper storeys

The next stage of the journey is taken by lift. It was felt there was a need to make these potentially alienating spaces more welcoming, so they are lit in a contrasting warm tungsten light, which is switched off when the cars are unoccupied.

On exiting the lifts, the upper-storey lobbies and bridges are under-lit, to be consistent with the rest of the lift core, while the atrium roof structure is uplit to ensure that the space appears light and airy, regardless of the tenants’ lighting. To give the building presence from the outside, it was crucial to illuminate the glazed external stair cores. The general lighting provided in the building was more than sufficient to achieve this; the challenge was rather to reduce the energy usage and significant light spill that would otherwise result from the high proportion of glazing.

Controlled responses

“What we actually developed was an integrated set of fittings and a control solution that responds both to natural light and movement,” explains Howis. “When natural light levels fall, the lighting adopts a very low-level resting state, at about 10 per cent output, so for the most part the stairs have a nice lit presence, but still don’t use much energy.

“When a person enters the stair core, the activity is sensed and the lighting picks up rapidly, illuminating the space as well as the adjacent half-landings. “Picking up on the building’s user activity creates a human element to the building and, because it’s also visible from the exterior, it gives a nice level of animation on the outside of the building.”

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