One Great St Helen’s, London EC3

JRA is refurbishing and extending One Great St Helen’s, an office building originally designed by the studio in 1998, which sits at the centre of the City of London. Following the vacation of the tenant, the team is bringing the 4,500m2 building up to contemporary standards by extending the building two storeys, opening up the entrance and finishing all floors to renewed CAT A standards. JRA is also providing a suite of new amenities and dramatically improving the sustainability of the building. The original, striking curved façade and colour palette is being maintained, cementing One Great St Helen’s as an iconic development amongst the skyscrapers of the Eastern Cluster and a bridge between old and new.

JRA originally designed One Great St Helen’s, taking design inspiration from the surrounding context and materiality of what was Crosby Square, and the nearby 13th century church, St Helen’s Bishopsgate. At the time, it was one of the first office buildings to be designed to the newly published British Council for Offices Specification and it was a BCO Award winner in 2000. Upon completion, One Great St Helen’s became Hiscox’s HQ, and they occupied the building for 25 years. During this time, Crosby Square became home to skyscrapers including 22 Bishopsgate, the tallest office building in London, the Leadenhall Building, and 30 St Mary’s Axe, forming the Eastern Cluster in the City.

Externally, JRA is retaining the distinctive curved glazed façade that sits between two red sandstone ‘bookends’ and replicating it at the extended 11th floor. Internally, the reception will be fit out in a palette of timber and terrazzo, creating a high-quality, contemporary entrance space with a new lobby area for touchdown and informal meetings. A new lightwell will be created at ground floor level to bring light down into the lower ground floor offices, and all office floors will be renewed with efficient, exposed services. The floor plates will be finished to CAT A, maximising space, light, and flexibility.

A new landscaped roof terrace and winter garden will be located at level ten, creating a mix of indoor and outdoor amenity space for year round use shared by occupiers. A new plant floor has been built at level 11 to maximise the terraces’ available space and the existing passenger lift has been extended to ensure accessibility for all. At basement level, JRA is creating new cycle storage and end of trip facilities in the former car park, repurposing the existing car lift for transporting cyclists down from street level.

One Great St Helen’s prioritises sustainability. Retaining the existing building saved significant carbon and its original design features, including the modulation of the curtain wall and the fins between cladding panels, reduce solar gain. New measures include efficient upgraded MEP services, improved insulation, and reuse of the existing raised floor. An all electric strategy implementing air source heat pumps and VRF systems for heating and cooling will exceed the requirements set out in the London Plan and the building will achieve 57% improvement against the Building Regulations Part L carbon emission target. One Great St Helen’s is predicted to attain BREEAM Excellent certification.