The SFE Façade Design and Engineering Awards recognise excellence and achievement in façade engineering. We will be using the SFE newsletter as a platform to showcase some of the winners from 2023.
WSP's Paddington Square was awarded first place for the New Build UK category.
- Client: Sellar
- Architect: Renzo Piano Building Workshop, Adamson Associates
- Facade Engineering/Consultant: WSP
- Facade Contractor: Focchi, Mace (main contractor)
Paddington Square in West London stands as a testament to modern craftsmanship and engineering excellence. Designed by the Renzo Piano Building Workshop, this 17-story building features 350,000 ft2 of office space, 80,000 ft2 of retail and dining areas, and a public piazza. Its design not only emphasizes aesthetics but also incorporates significant advancements in sustainability and occupant wellbeing.
All pictures copyright of Hufton + Crow Photography
The building's façade, engineered by WSP and constructed by Mace, embodies transparency and efficiency through a combination of bespoke unitised and stick curtain walls, and a travertine rainscreen. The use of low-iron glass and ultra-clear interlayers, alongside alternative solar-control options, allows for ample daylight penetration, reducing the reliance on artificial lighting and enhancing occupant comfort.
One of the standout features of the façade is its innovative use of Vierendeel-type mullions and transoms. These components support large spans without vertical members, creating a seamless and unobstructed view. This approach was further enhanced by incorporating Brunel-inspired external fins, which act as structural elements, reducing the mullion sizes and improving the perceived transparency.
WSP Facade Engineering team faced several challenges, which they overcame with precision and ingenuity. The façade's double-skin structure includes a vented cavity, integrated blinds, and an external brise soleil. This configuration helps control solar gain and reduces cooling loads. Detailed computational fluid dynamics (CFD) analysis and finite element method (FEM) structural models were employed to ensure the façade met stringent thermal performance targets and maintained safe temperature control for annealed glass.
A key innovation was the use of castellated mullions, where the external fins act as structural supports. This design choice significantly reduced the size of the mullions and improved the façade's transparency. The inner and outer skin mullions are connected via moment connection brackets hidden within the spandrel zone, while two simple struts connect the two skins, limiting mid-span deflections. A bespoke gasket ensures natural ventilation of the cavity while sealing against rain and noise.
To maintain efficiency and minimize the carbon footprint, the project utilized remote camera monitoring, 3D printing, prefabrication, and large-scale installation. Prefabricated elements, such as the scenic lift pulley-room enclosures, were assembled offsite, ensuring high build quality and reducing on-site construction time.
The façade's performance was optimized to avoid the need for heat-treated glass, further lowering embodied carbon. The use of a double-skin structure with integrated blinds and external shading devices effectively controls solar gain, enhancing energy efficiency and occupant comfort.
Paddington Square's innovative façade is a benchmark for future developments, combining aesthetic appeal with high performance standards and sustainability. The project's success lies in its meticulous design, advanced engineering solutions, and the seamless integration of cutting-edge technologies. This building exemplifies how thoughtful design and engineering can create sustainable, efficient, and visually striking urban spaces.