Interview with Tristram Carfrae of Arup
We know the architects behind the design of such icons as the Sagrada Familia in Barcelona and the Sydney Opera House, but such demanding projects are not without the support of engineers. Tristram Carfrae, an engineer from Arup, talks about the challenges they face in their construction.
The Sagrada Familia in Barcelona
Photo: Canaan | Wikimedia Commons © CC BY-SA 4.0
Sagrada Familia construction is 2 years away from completion
Ola Kloc: You are currently helping to complete the construction of the Sagrada Familia in Barcelona, what are the challenges involved?
Tristram Carfrae: Antoni Gaudi's Sagrada Fam ilia Cathedral in Barcelona is scheduled to be completed in 2026, one hundred years after the death of its creator. When the project was about 60 percent complete, however, there was a problem with the weight of the structure. Building the remaining six towers, dedicated to the four evangelists, the Virgin Mary(Mare de Deu) and Jesus Christ, could make the structure too heavy for the foundations and crypt below. As a result, the Sagrada Familia Foundation turned to Arup for help with the rest of the structure's design.
We developed a scheme using the stone itself as the structure, which reduced the weight of the towers. The introduction of this solution also had a positive impact on construction costs, sped up operations and made the work less carbon intensive. The project usedpre-stressed stone masonry panels as the basic structural element. Using a combination of modern digital technology and traditional craft methods, the stone panels are precisely made in the workshop and transported to the construction site, where they are assembled like "lego blocks." The assembly looks spectacular, so passersby who witness this "construction spectacle" are eager to watch. This solution also strengthens the structure in case of possible earthquakes or strong windstorms.
© Arup
Arup's previous experience
Ola: By the way, this is not the only one of the icons to which you have put your hand. Which projects required the most engineering gymnastics and why?
Tristram: A challenging project in terms of construction was the Water Cube created for the 2008 Beijing Olympics [the CSCEC International Design studio is responsible for the design of the Beijing Olympic Swimming Pool - editor's note]. The form of the building is inspired by the natural formation of soap bubbles. We also implemented sustainable solutions - we used ethyl-tetrofluoroethylene (ETFE) for the facade, which makes the facade weigh just 1 percent of a potentially identical glass structure and is an excellent thermal insulator. It also provides ample access to daylight, saving about 55 percent of the energy needed to light the recreation halls.
Water Cube in Beijing
photo: charlie fong | Wikimedia Commons
Also significant was the Sydney Opera House project [design: Jørn Utzon - editor's note], which pushed the boundaries of engineering, forcing engineers and architects to develop then-unknown solutions. As many as 12 schematics of the iconic design of concrete sails holding 1,056,006 ceramic tiles were created. The effect of the wind on the curved surfaces of the sail had to be thoroughly tested through wind tunnel tests for buildings, something that is now commonplace in the design of large buildings around the world. The design of the opera house's glass walls, on the other hand, forced our team to undertake research into the behavior of laminated glass in objects. This made it possible to use glass as a structural material on such a large scale for the first time.
Sydney Opera House
Photo: Windmemories | Wikimedia Commons © CC BY-SA 4.0
we need consistent global standards
Ola: During your meeting at Arup, you talked about strategies to reduce carbon emissions in structural components. What actions and design decisions should we take to realistically reduce the environmental impact of construction activities?
Tristram: Clear global definitions and certifications for decarbonization would be very helpful. Currently, each region separately strives for climate neutrality, creating its own standards that are often inconsistent with the others. This causes complexities in global systematization and hinders the development of sustainable construction. This is described in detail in the Arup report "Net-zero operational carbon buildings: state of the art." We also need a change in the approach to design to one that puts the well-being of people and nature at the center. Such an attitude will result in low-carbon components being chosen and materials being reused to reduce waste. Renovation of existing buildings is also seeing increasing value. Rather than building new, there is value in retrofitting, improving energy efficiency, reducing greenhouse gas emissions and positively impacting occupant health and comfort. Our analysis at Arup shows that creating new construction can have carbon emissions as much as 180 percent higher and overall greenhouse gas emissions 47 percent higher than retrofitted buildings, counting lifetime emissions. This means that retrofitting is much more environmentally friendly.
Ola: Thank you for the interview.
