Successful integration into the city cluster

52 Lime Street, also known as “The Scalpel”, is a prime example of the successful integration of modern project architecture into the historic structure of the City of London.

The impressive 190-metre-high office tower, designed by architects Kohn Pedersen Fox (KPF), is viewed extremely positively by Londoners, as it improves the north-south connection through the district and creates an attractive public square at its base, reminiscent of the historic Lime Street Square, which was lost in the 1940s.

The geometric shape of the building cleverly leans away from the Leadenhall so that it is virtually invisible behind St. Paul’s Cathedral – the roof line slopes steeply to the south in recognition of the existing overall composition of the surrounding architecture. To support the geometry of the building, facade builder Scheldebouw used bright, metallic rebate lines and the “ipasol shine 49/28” solar control glass on Clearvision white glass from AGC Interpane, which has a silvery-blue effect with increased external reflection.

Lime Street is a side street in the City of London, between Fenchurch Street to the south and Leadenhall Street to the north. This is where the striking new office tower “52 Lime Street”, known as “The Scalpel” due to its sharp shape, was built. Despite its impressive 42 storeys, this addition to the city cluster, which is popular with Londoners, manages the feat of perfectly maintaining the close-up and distant views in the historically grown district. The geometry of the building recedes at key sight lines, leans out of view and at the same time impresses from another position with its radiantly bright glass facade. The silvery-blue reflective solar control glass ipasol shine 49/28 was used on the particularly low-iron and neutral white glass “Clearvision” to give it an aesthetic that always adapts to the sky in the different lighting moods of the day. The double silver coating has a discreet external reflection of 23 percent and protects the building – also important for climate resilience – from overheating in the warm season with a low g-value of 28 percent, which reduces the climate load. At the same time, 49 percent of visible daylight is still transmitted to reduce energy costs for electric lighting and increase comfort for building users. Facade manufacturer Scheldebouw was responsible for the development of the more than 20,000 square meter double-glazed facade, which, as structural glazing, corresponds perfectly with the bright metallic fold lines of the structure. With a Ug value of 1.1 W/(m2K), it reduces heat loss in cold outside temperatures. For the glazing of the two-storey lobby, AGC Interpane manufactured so-called “Giga Lites”, i.e. oversized insulating glazing, in this case with a height of 7.70 meters. To ensure the necessary safety, laminated safety glass (55.4 laminated toughened low-iron float) was used for the interior panes in the structure.

With the successful integration of “The Scalpel”, the architects at KPF impressively demonstrate how important it is for buildings not to stand in isolation from one another, but to interact with their surroundings and make a meaningful contribution: The office building does justice to both its urban surroundings and the growing climatic requirements, as KPF placed particular emphasis on clever “passive” design principles: The strategic arrangement of the building core on the south facade ensures that the interior spaces are largely protected “per se” from extreme solar radiation. The fully glazed building’s carbon emissions from its operation are therefore around 25 percent below local regulations. KPF also optimized the use of resources and saved 700 tons of steel during construction by carefully calculating the design of the floor beams. Pre-stressing the vertical core of the building allowed the construction of slimmer core walls, which ultimately saved another 1,800 cubic meters of concrete. The 52 Lime Street building has been shortlisted for the “Building of the Year” award by “The Architects‘ Company”. The award recognizes completed buildings that make a positive contribution to public life in the City of London and are characterized by innovative design, high environmental standards and an adaptation to the history and changing context of the city. “The Scalpel” also received the BREEAM ‘Excellent’ certificate.