Winner of the prestigious International Highrise Award 2022, the Quay Quarter Tower overlooks Sydney Harbour and the iconic Sydney Opera House while actually concealing a 1970s office building. Located in fact in the central business district of the Australian metropolis, the tower was originally built in 1976, but in recent years it was beginning to lose tenants to newer towers. An international competition was therefore launched in 2014 to redesign the building, on the condition that the existing architecture would not be demolished and any new design should retain as much of the original structure as possible.

The winning design by the Danish firm 3XN, retained most of the structure and concrete core of the original building-saving 65 percent of the concrete floors, beams and columns, as well as 95 percent of the concrete core housing the elevator shafts and emergency stairwells-but drastically reshaping the rectangular floors into a series of rotating trapezoids totaling 49 stories.

Inside, however, spaces are built around large atriums on various levels that create hubs of activity and emphasize the building’s sense of community, opening lines of sight and communication between floors and functions, and helping to bring natural light into each floor of the 21,000-square-foot building.

Materially, a projecting brick facade treatment acts as passive solar shading, sheltering the building from 30 percent of solar gain and eliminating the need for blinds to obstruct views.

In addition to the interesting design approach, these reuse choices helped significantly reduce the site’s environmental footprint in the construction of a building that also anticipates operational carbon emissions will be significantly lower than those of the original building, despite its larger capacity.

“In terms of adaptive reuse, I think ten or even five years ago you would have thought that there is always a trade-off with commercial viability,” says Fred Holt, 3XN partner in charge of the project. “What we’ve demonstrated with the Quay Quarter Tower is that you don't have to compromise to be environmentally sustainable with upcycling, and you actually save money.”