The world’s first ‘upgraded recycled’ solar building

The new 206-meter-high building was built into an old building that has existed for decades, saving up to $102 million and reducing CO2 emissions.

Once the tallest building in Sydney, AMP Center is now obsolete with a structure from the 1970s. The owners wanted to replace the building with a larger, better and more energy efficient building.

However, the demolition of high-rise buildings has many environmental impacts, from construction waste to the CO2 emitted by heavy machinery. So, in 2014, the Australian company AMP Capital held an architecture competition with a unique request: Build a new skyscraper without destroying the old one.

As a result, a new building called Quay Quarter Tower was born and is considered the world’s first “upcycle” high-rise building. Quay Quarter Tower opened earlier this year and was selected as the World Building of the Year 2022 at the 15th World Architecture Festival (WAF) on December 2. With 49 floors and a height of 206 meters, the new building retains more than two-thirds of the old structure, including beams, columns and 95% of the core.

After removing the unused parts of the AMP Center, the workers erected a new structure next to it, then “assembled” into the rest. A modern glass exterior wraps around both to form a seamless building. The new design doubles the old floor area, the capacity increases from 4,500 to 9,000 people.

The architects believe that this method helps to reduce 12,000 tons of CO2 compared to demolishing the AMP Center and rebuilding it from scratch. In addition to reducing the use of carbon-intensive materials such as concrete, the project also saved construction time by up to a year and cost savings of up to $102 million.

Danish architecture firm 3XN, British engineering firm Arup and Australian architecture firm BVN collaborated on this challenging project. One of the first challenges was to determine if the old building would match the original design.

High-rise buildings often shrink under their own weight, especially during the first few months after completion. As a result, the AMP Center is slightly different from the old drawing, the concrete expands and falls down when completely dry, according to Fred Holt, architect at 3XN.

Only when construction begins in 2018, architects and engineers will be able to take a closer look at the old building. They used concrete samples to calculate how to add structural loads.

Buildings shrink over time also leads to another problem: What if the old and new structures become misaligned as the old structure shrinks?

To fix it, the team of engineers installed hundreds of sensors around the building to monitor the smallest movements. The data is fed into a computer model – a digital replica of the building. Based on that, experts will make real-time adjustments. The workers also left a 4m gap between the new and old structure until the final stage of construction, giving the new concrete time to settle.

The design of Quay Quarter Tower consists of 5 large blocks stacked on top of each other, twisted and reaching to the sky. Described by the architects as a “vertical village”, the building features multiple terraces, retail and office spaces overlooking the Sydney Opera House. The old and new structures blend seamlessly to the point of being undetectable from both the outside and the inside.