The Quay Quarter Tower in Sydney has set new standards in building refurbishment. Through an “upcycling” process, the 1976-vintage skyscraper was completely renovated, and the amount of usable floorspace was doubled. The combined benefits of economy and sustainability are a boon for users and owners alike, as well as for the environment and for society. We interviewed the architect, Aleksander Kongshaug from 3XN, about the underlying concept and the significance of this beacon project.

Circular Quay, Sydney, Australia
Image: Circular Quay, Sydney, Australia

With its unusual shape and futuristic design, the Quay Quarter Tower (QQT) has become a striking landmark in Sydney’s Circular Quay quarter. On the outside, there is nothing to remind us of the former AMP high-rise that took shape at this site in 1976. And yet the present-day QQT owes a lot to the original structure – about 95 percent of the building core was retained in this gigantic upcycling project. The refurbishment and retention of more than 20,000 cubic meters of existing concrete greatly reduced the burden on the environment. Sika’s solutions made this pioneering project possible, thus extending the building’s lifespan by another century. 

Many people recycle their waste. But whole skyscrapers? Is the new Quay Quarter Tower (QQT) in Sydney the biggest recycling project in human history?

I don’t know about that, but it’s definitely a massive one within architecture. The QQT has become the new baseline for architecture, how we view the built environment, and what’s doable to extend the longevity of an existing building. Around 90% of the time, when architects begin a project, there’s already something there to be handled. The response that the QQT has received over the last half year shows that the whole architecture industry – and demand for this approach – is pushing in this direction. 

We must become far more aware of what’s around us. There’s certainly an economic driver for this kind of work, but there’s also a social driver. This means being a good citizen and giving something back to the city. The adaptive refurbishment of the QQT doubled the area of the floor plate. This is fantastic, but our responsibility to the city doesn’t stop there. It also means minimizing the time on site, and reducing the pollution and noise created by trucks driving in and out. 

Aleksander Kongshaug, architect working for 3XN/GXN Architects in Copenhagen
Image: Aleksander Kongshaug is an award-winning Danish architect working for 3XN/GXN Architects in Copenhagen, the studio responsible for the new QQT. Trained at the Royal Danish Academy of Architecture and ETH Zurich, his career has also taken him to the US, the UK, Latvia, and Oman. He is a published expert in areas including circularity, green building, and extreme environments.
Readers will see how cool the building is from the magazine. But it’s even cooler when you understand the construction process. Can you briefly explain it? 

We took an existing skyscraper built in downtown Sydney in 1976 and completed an adaptive refurbishment. The floorplates in many old towers like the QQT are 1,000 to 1,500 square meters max. These days most tenants are looking for a minimum of 2,000. 

Just because the QQT was no longer fit for purpose didn’t mean there weren’t substantial portions that could be recycled. We reused two-thirds of the existing building overall and two-thirds of the columns and beam slabs. We kept 95% of the core, which allowed us to solve the problem of increasing the floor space. Even with double the square meters, the new QQT doesn’t overshadow the surroundings any more than the existing building did.

Was it difficult to sell such an unusual idea to the client? What persuaded them?

The fact that we could double the floor space and let in more sunlight was very persuasive.

We can talk a lot about circularity, reuse, upcycling, and so on, but we won’t be able to convince any developer to recycle like this unless there’s a strong economic case. Because we were able to reuse so much material, our proposal for the new QQT saved the client money. This money could be invested back into the building, for example by creating large atriums that are more attractive to tenants and create a neighborhood feel. Our approach ended up saving nine months of building and demolition work, labor costs, and pollution. That alone amounted to savings of around 86 million Australian dollars.

But alongside financial considerations, another motive was good citizenship: Any developer has a responsibility to the city where they build. They must show that they’re good citizens by giving back to the area and creating life in it.

Did the project pose any special challenges for you? Or the building contractors?

The biggest challenge was in the planning phase of the construction. Retaining the core isn’t easy, and it’s something we to some extent had to learn while doing. Our plan involved reinforcing the existing concrete and inserting a new steel structure to double support the old floorplate. This is a building for people, so we had to convince the city authorities that it would be functional and safe. Engineers had to be confident in the fifty-year-old concrete that was retained and reinforced to sign it off as capable of standing for the next hundred or hundred and fifty years.

Is there much potential for this kind of adaptive reuse as an alternative to demolition and new build? In what percentage of cases worldwide do you reckon this type of upcycling could be a viable alternative? What kinds of buildings make suitable candidates?

I couldn’t name an exact percentage, but the answer is a big Yes. We need to keep pace with population growth, so the demand for adaptive reuse will remain strong. In a city like London, for example, many buildings have a long life ahead of them, but they cannot meet existing market demands. So, developers want to tear them down and erect new buildings. The same thing in New York: there are sites where it will take years to demolish and rebuild new structures, and doing so is a messy process that generates lots of chaos and pollution. 

The Quay Quarter Tower in Sydney, Australia
"We must start asking ourselves where we can save not only carbon emissions, but also time, money, and materials. There are vast numbers of office buildings from the 60s, 70s, 80s, and 90s out there that nobody really cares for. We need to upcycle the value embedded in them." Aleksander Kongshaug, 3XN/GXN Architects in Copenhagen
The Quay Quarter Tower in Sydney
Image: Thanks to its expertise, Sika makes flagship projects such as the Quay Quarter Tower in the heart of Sydney possible: Sika solutions have played a significant role in the renovation of this building, which dates from 1976, and have allowed the amount of usable floorspace to be doubled.
Can you say more about the environmental benefits of the way the QQT was built? 

We saved 12,000 tons of CO2  with the refurbishment of the QQT, so carbon is obviously a massive driver. Life cycle assessments and measurements of the carbon footprint are often only done after the design. But because we were working within the constraints of an existing site, we adopted an iterative approach that involved measuring the carbon footprint of each layer so we could make the right decisions as we went along. 

What role did Sika’s products and expertise play in the design and construction of the building? 

Without Sika’s products and expertise, we wouldn’t have been able to retain the 23,000 cubic meters of concrete, which is basically the entire core of the building.

Without that know-how, we couldn’t have reinforced it to extend its lifetime by another 100-plus years.

The architecture of the QQT has earned many awards. Has it also generated interest from prospective clients interested in novel approaches to building or rebuilding? Can you reveal whether similar projects are already in the pipeline?

I can’t mention names, but at the moment we’re working on a tower in London where there’s already an existing structure. Our first goal is to convince the client that we can retain the existing tower but change the facade. To compare, we’re also designing a new tower on the same site so that we have these two set against each other. We’re doing this so we don’t miss any points of keeping the existing structure. 

Do you think this approach can go even further? Can you imagine other ways to increase material, resource, time, and cost efficiency as well as sustainability in construction?

Yes, it’s all about adaptability and design for disassembly. Our approach is to think of buildings in terms of layers. Each of these layers has a different lifetime, starting with the facade, which has a life of maybe 35 years, all the way to the structure, which may live over 100 years. To be able to reuse the different layers and service the building at the easiest level, we need to be able to access these layers.

We’re going to design buildings increasingly on an intelligent modular basis so that they can be reused without huge amounts of expensive demolition work.

Removing concrete to modify a building is messy and energy-intensive work. So, if you’re using concrete in the design of an adaptive building, then you must use it intelligently. In one design, for example, we’ve used concrete modules screwed together with mechanical joints. It’s a bit like Lego bricks. We could have designed that building with wood, but we wanted to prove our point that it’s also possible to use concrete for flexible buildings and doing so saves time. Later on, you can add or remove modules as required. So, if you want flexibility, you don’t have to go for wood.

How do you see the construction industry evolving? What role do you think circular economy and digitalization will play?

When starting work on an existing building, we usually have no idea what’s in it. New digital technologies allow us to integrate data into our designs, which help us get an overview. The more information we have on our buildings, the easier they’ll be to maintain, service, and reuse – and adapt over time. A digital material passport will enable us to do things more intelligently and access the relevant information more easily.

Circular economy and digitalization are important. But given that there are so many stakeholders, manufacturers, demolition experts, and consultants involved, it might come down to finding the right team and making sure that everyone along the value chain is on board. Because if just one player isn’t working with the same principles or doesn’t understand the value of circular building, the whole thing can fall apart.

What is the vision of your company?

We believe that architecture shapes behavior. This informs all our work as we continue to explore ways for enriching the lives of people living in our buildings.

This means that for the last decade, we haven’t been too focused on where the market is going, but instead have pursued our vision for how we want it to go. We want to continue as a research and science-driven studio that remains at the forefront of construction industry trends.