Climate protection in construction also includes reusing entire buildings and their building materials

Rendering of the refurbished building.The building with British Telecom as its resident.

The city can become a quarry, as the architects from Kohn Pedersen Fox Associates (KPF) are demonstrating with the “Panorama St. Paul’s” building

Update: The Circularity Gap Report examines the state of the circular economy every year. The figures in the current edition are sobering: the proportion of secondary material has fallen from 9.1% in 2018 to 7.2% (2023).
https://www.circularity-gap.world/global/

 

“Reusing buildings” is a buzzword that is appearing more and more often in current architectural discussions. In practice, this means “continuing construction”, i.e. adapting the existing structures and areas to the new requirements, combined with the well-known recycling of building materials. A current example of this is the “Panorama St. Paul’s” building in the City of London with an exclusive view of the famous cathedral.

It is an 1980s office complex covering an entire block and originally housing the British Telecom.

The renovation was carried out by Kohn Pedersen Fox Associates (KPF); upon completion, planned in the second half of 2025, there will be staircase-like façades with ample greenery, a large screen on the ground floor for artistic presentations, a passage through the block towards St. Paul’s and a roof garden with restaurant on the upper floor.

Structure of the building: old-new.

All of this will be open to the public – one can already predict that the new view of the cathedral will be a highlight for Londoners and tourists.

“It is the first net zero carbon-enabled office development in London,” says John Bushell, design principal at KPF.

As far as the recycling of stones is concerned, the buzzword “urban quarrying” appears in a report in the Architects’ Journal (May 13, 2024), i.e. the removal of new building materials from existing old ones. The ancient Romans did it that way.

KPF has had reuse and repurposing in mind for some time. There is a “Adaptive Reuse” section on the architecture firm’s website.

At Panorama St. Paul’s, formerly known as 81 Newgate Street, around 70% of the existing concrete structure was retained. Almost 100% of the natural stone from the façade was reclaimed and reused. A total of around 1500 t of Portland limestone and granite were involved:
* A zero-to-landfill policy was implemented, which means that no construction waste was generated for disposal in landfills;
* Resources were saved by reusing the natural stone;
* By continuing to build, compared to a new building, considerable construction time was saved and costs were also reduced;
* the greenery on the terraces will improve the city climate.

The experiences with reusing the façade stones are presented in detail in the article in the Architects’ Journal. We link to the magazine below and discuss individual aspects here, as KPF informed us.

Reusing the stone cladding at the facade.Reusing the stone cladding at the facade.

The project showed that reusing architecture is easier said than done. Because: Panorama St. Paul’s got thermal insulation in the façade, and the windows, for example, were larger. Even if the façade grid was generally retained, this meant a new layout for the façade panels, unless they wanted to be recut and thus create waste again.

This was no easy task, especially in the case of the corner pieces.

Special stonemason know-how was needed to hang the stones from the old façade. This is simply because there was no documentation from the 1980s and you had to be careful not to damage the stone plates. The craftsmen often did not initially know what the quality of the individual stone slabs would be after almost 40 years in London’s smog.

In the end, however, it became clear that the goal of continuing to build and reuse is achievable: in the case of natural stone, “the waste was very small,” according to KPF.

The company Grants of Shoreditch, based in Chelmsford, around 50 km from the construction site, took over the cleaning and refurbishment of the stone slabs. The new large elements for the façade were also created in their factory.

Another important experience was actually banal: every building is different, and so you find yourself at the very beginning of continuing to build and reuse with every new project.

Kohn Pedersen Fox Associates (KPF)

Architects‘ Journal

Grants of Shoreditch

Photos/Renderings: Kohn Pedersen Fox Associates (KPF)

“Panorama St. Paul’s” (left) and St. Paul’s Cathedral (right).