How one40william shaped Perth’s skyline and the future of our sustainable urban developments

Take a closer look at three design approaches proven to stand the test of time — for people, places and the planet.

More than a decade on, we consider the legacy of one40william in Perth, Australia - a landmark CBD development by Cbus Property, and reveal the forward-thinking design directions that defined this project while propelling our award-winning urban developments into a sustainable future. Projects that continue to give back to the city and its inhabitants.

People flow through and gather at one40william making it both a destination and CBD gateway. All images: Peter Bennetts.

Downtown desert to upscale destination

One40william occupies a prime inner-city location adjoining Yagan Square and the Perth Underground railway station to the CBD. The challenge wasn’t just to integrate a large-scale office and retail complex into streetscapes studded with heritage buildings over an underground Perth Metro station. It was to create a vibrant village that would attract and connect visitors and workers into the heart of the CBD, where they can enjoy the best of retail, food and entertainment as well as forward-thinking workplaces. 

Taking inspiration from Melbourne’s bustling city laneways, one40william’s lower two levels have been reimagined into laneways and public squares studded with retail and food outlets. Accessed by several entry points, the building is porous by nature, creating linkages with the surrounding city, and blurring the public and private, social and workplace boundaries. Capturing footfall from multiple vantage points and funnelling it back into the CBD has led to the reinvigoration of the site and channelled much-needed vibrancy back into the city.

What makes one40william stand out is that it is so publicly accessible rather than completely privatised. Permeable links allow people to easily flow around, through and under the building while exploring one40william’s variety of retail, hospitality, workplace and landscaped spaces. 

The result,” noted judges for the Australian Institute of Architects (AIA) Awards, is a commercial project that delivers heritage, sustainability, urban and workplace outcomes that create a new benchmark for commercial projects in Perth.”

Extensive, accessible roof top gardens activate one40william’s fifth façade’ and are an important environmental buffer.

A place in the sun… and shade

Creating inviting winter gardens and and roof terraces were key strategies in delivering our biophilic workplace environment. These green spaces both celebrate and mitigate Perth’s frequently harsh climate conditions.

When the Western Australia Department of Transport relocated to one40william a decade ago, the winter gardens located on the northern side of the building held immediate and ongoing appeal for employees. 

Building Management Officer Alan Davidson says that staff remarked that they enjoy the fresh air, natural greenery, warmth in winter, and coolness in summer. They also appreciate the ability to hold meetings in an area that makes you feel that you are not in an office environment. It is a staff favourite for lunchtime catch-ups with colleagues.”

Extensive and intensive roof top landscaping on the seventh and 14th floors feature water-wise drought-tolerant plants, pebble tracts, and angular beds to complement the city’s striking skyline. These contemporary gardens have been designed for both maximum visual and sustainable impact.

Hassell’s recent projects in Perth and beyond take cues from the success of these landscaped exterior and interior spaces, notably in the climate responsive façade at Fiona Stanley Hospital in Perth and the cascading green terraces of Park Avenue Central in Shanghai. 

As we’ve seen through our research into Time Well Spent and Magnetic Workplaces, COVID-19 has reignited the discussion on the benefits of abundant green spaces — indoors and out — that become vibrant places to work, play and connect.”

— Principal Peter Dean

The 5-Star Green Star one40william sets new benchmarks for commercial projects’ according to AIA judges.

Sustainable beacon

One40william was one of Cbus Property’s first office buildings, blazing a trail in the industry for sustainable development.

When it opened, one40william was the largest commercial building in Western Australia to receive a 5-Star Green Star Office Design rating and a 5-Star Green Star Office As-Built rating. Since then, it has also received a 5.5-Star NABERS Energy rating for the office tower and exceeded the original 4.5-Star NABERS design rating. 

The robust design was best practice at the time and its strong fundamentals have enabled us to continually evolve its environmental performance, improving its credentials such as NABERS and Green Star Performance, so it is one of the most sustainable office buildings in our portfolio,” says Cbus Property’s Chief Executive Officer, Adrian Pozzo.

The sustainability principles implemented have since become a core pillar of our business, driving our sustainability strategy and informing how we develop our new commercial office buildings in the intervening years.”

— Cbus Property’s CEO Adrian Pozzo

Standing tall: one40william recognised as an industry exemplar and city-shaper in four major Australian Institute of Architecture Awards

Shining light

As well as being a beacon for sustainable development, one40william progresses social responsibility goals by celebrating heritage, developing new links between workplace, retail and public transportation, and creating a positive new shared, civic space.

One40william demonstrates that office buildings… can incorporate the demands of contemporary office planning while also responding to the finer grain of the city fabric, and in so doing create a successful mix of uses that is invigorating the city of Perth.” 


At the 2011 awards, the Australian Institute of Architects’ judges described one40william as one of Perth’s most significant and influential new buildings. The project won four major awards.

  • 2011 AIA (National) Walter Burley Griffin Award for Urban Design 
  • 2011 AIA (WA) George Temple Poole Award for overall winning architectural project 
  • 2011 AIA (WA) Ross Chisholm Award for Commercial Architecture 
  • 2011 AIA (WA) John Septimus Roe Award for Urban Design

Presenting the George Temple Poole award, the judges noted the links between one40william and neighbouring buildings, including the GPO Building on Forrest Place and the heritage buildings on Wellington St. Hassell was commended for changing Perth’s skyline and helping to establish a deeper north-south alignment in the CBD. The integration of winter gardens and roof terraces was highlighted and an overall design that minimises energy and water consumption while maximising natural light.

The real success of the project from an urban design perspective is at the ground plane where the building blurs the boundaries between public and private, social and workplace, circulation and interaction.” 

— AIA judges

One40William has achieved these sustainability ratings.

  • 5-Star Green Star Office Design
  • 5-Star Green Star office As-Built
  • 5.5-Star NABERS Energy rating for the office tower
  • 4.5-Star NABERS Design rating (exceeded)

In the past five years, Cbus Property reported a 12.27 percent decrease in electricity consumption and a 27 percent decrease in water consumption. The project’s sustainable features include:

  • high efficiency low temperature VAV air conditioning
  • heat recovery (a heat exchanger in the mechanical system that extracts heat from the AC return air and uses it to power the cooling system)
  • peak load’ generator topping, which enables the building operations to run independently from the main electricity grid reducing the demand on the network preventing brownouts
  • waterless urinals
  • transport options that promote a reduction in car use and increase in physical exercise (public, bicycle, end-of-trip, reduced car parking).

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