The new building in the City of London is also called "The Scalpel" because of its sharp-cut shape. The building's form creates an attractive public square at its base, reminiscent of the historic Lime Street Square that was lost in the 1940s. The geometric form of the building cleverly leans away from Leadenhall, making it virtually invisible behind St Paul's Cathedral.
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To support the building's geometry, facade builder Scheldebouw used bright, metallic fold lines and "ipasol shine 49/28" solar control glass on Clearvision white glass from AGC Interpane, which has a silvery blue appearance with increased external reflection.
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The building geometry recedes at crucial sight lines, leans out of view and at the same time impresses with its radiantly bright glass facade from another position. In order to give it an aesthetic appearance that always adapts to the sky in the different lighting moods of the day, the silvery-blue reflective solar control glass ipasol shine 49/28 was used on the particularly low-iron and neutral white glass "Clearvisi-on".
What are the technical values of the glasses from Interpane?
The double silver coating has a discreet external reflection of 23 per cent and protects the building - important also for climate resilience - from overheating in the warm season with a low g-value of 28 per cent, which reduces the climate load.
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At the same time, 49 per cent of visible daylight is still transmitted to reduce energy costs for electric lighting and increase comfort for the building's occupants. Facade builder Scheldebouw was responsible for the development of the more than 20,000 square metre double-glazed facade, which, as structural glazing, corresponds excellently with the bright metallic fold lines of the structure.
With a Ug value of 1.1 W/(m2K), it reduces heat loss in cold outdoor 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 m each. For the required safety, laminated safety glass (55.4 laminated toughened low-iron float) was used for the interior glass panes in the structure.
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With the successful integration of "The Scalpel", the architects of KPF impressively demonstrate how important it is that buildings do not stand isolated from one another, but interact with their surroundings, meaningfully integrating themselves: The office building does justice to both its urban environment and the growing climatic requirements, because KPF placed particular emphasis on clever "passive" design principles: The strategic arrangement of the building's core on the south facade ensures that the interior spaces are largely protected "per se" from extreme solar radiation.
The carbon emissions of the fully glazed building from its operation are therefore about 25 per cent below local regulations. KPF also optimised the use of resources and saved 700 t of steel during construction by carefully calculating the design of the floor beams.
Pre-stressing the vertical core of the building allowed for the construction of slimmer core walls, which ultimately saved another 1800 cubic metres of concrete.
The building at 52 Lime Street was shortlisted for the Building of the Year award by The Architects' Company. The award recognises completed buildings that make a positive contribution to the public life of the City of London through innovative design, high environmental standards and an adaptation to the city's history and changing context. "The Scalpel" also received the BREEAM certificate "Excellent".
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