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505 George Street Sydney

Lofty ambition: setting a green agenda for a 270m high residential project

In recent years, we have seen significant innovation in sustainable building design in the commercial sector, but are we doing enough in the residential sector?

On track to become one of the tallest zero-carbon ready residential buildings in the world, Architectus Senior Associate, Gary Henighen, explores how future project 505 George Street will contribute to new sustainability benchmarks in the residential sector.

We are experiencing the effects of a climate crisis and, finally, it seems to be on everyone’s agenda. Forcing change and realising the ideals of sustainable design represents the most significant contemporary challenge faced by our industry. It calls for us to experiment, collaborate and learn quickly, to design places that respond to their climate and surroundings, and, finally, to be innovative and bold.

In mid-2019, Architectus was among 700 architects around the country who became signatories of Australian Architects Declare Climate & Biodiversity Emergency, a statement conceding the need for aggressive, industry-wide change in our approach to designing buildings.

Rapid urbanisation of cities is compounding the catastrophe. According to the Intergovernmental Panel on Climate Change, the world’s cities account for approximately 75 per cent of energy-related CO2 emissions, a figure far exceeding the 55 per cent of the global population who are urban dwellers. Within these metropoles, buildings are the single largest users of energy with most still powered primarily by fossil fuels. In short, city buildings are punching far above their weight as major contributors to climate change. If cities are to remain liveable through unprecedented population growth, they will have to rapidly adapt to become considerably more efficient, with Copenhagen leading the way as one of the world’s first carbon neutral cities.

There is an awful lot to be done, but some encouraging progress has already been made. Technological advances in the last decade have been a catalyst to a new age of intelligent and environmentally responsible buildings around the world. We are now starting to witness the first net-zero energy buildings, sky-scraping urban forests and a shift towards buildings that do not rely on burning fossil fuels for energy.

However, while cities have given rise to ever greener commercial and public buildings, comparable projects in the residential sector – with a few noteworthy exceptions – have often lagged in their application of passive design principles and uptake of renewables or energy-saving innovations.

Leaders in sustainable design

In early 2018, Architectus and Germany’s ingenhoven architects identified the design competition for the residential development at 505 George Street as an opportunity to challenge this status quo. This project is being undertaken by Coombes Property Group as owner and developer with Mirvac as development manager. Together, the two practices conceived a 270-metre tower – Sydney’s tallest residential development – with the infrastructure to fully transition to renewables by 2030, a feat yet to be achieved in an Australian development of anything close to this scale.

Ingenhoven architects and Architectus came to this project with shared history. Opening in 2011, the two practices’ first collaboration, 1 Bligh Street was applauded as a global example of well executed sustainable design principles. That building was Australia’s first office tower with a full double-skin facade and a bold approach that provides natural ventilation, social interaction in the atrium spaces and natural daylight to office spaces. With its innovative and elegant design, the tower won a sweep of prestigious awards, including the 2012 Australian Institute of Architects NSW Awards’ Milo Dunphy Award for Sustainable Architecture. In 2019, it was named among the world’s 50 most influential tall buildings of the last 50 years by the Council on Tall Buildings and Urban Habitat.

Pushing the boundaries of green design

In the years since, both practices have continued pushing the boundaries of green design. Ingenhoven architects are global leaders in the field of sustainable architecture. Their substantial portfolio includes landmark projects such as Freiburg Town Hall, the world’s first public net-surplus-energy building, generating more energy than it consumes. Ingenhoven architects also championed the Architects Declare movement in Germany and is one of the ten founding members of the Architects Declare in Germany.

Among other breakthrough projects, Architectus is currently working on another significant collaboration with Singapore practice, WOHA to design a first principles green residential tower at Brisbane’s 433 Queen Street (Cbus Property). A thoughtful and specific response to Queensland’s sub-tropical climate, artists impressions of the proposed 5 Star Green Star development depict an almost utopic building, cooled by ocean breezes and draped head-to-toe in tropical greenery. Both practices’ achievements have been underpinned by a utopian refusal to rest on the laurels of past projects.

As we developed the design for 505 George, sustainability consultancy Cundall were commissioned to provide sustainability advice and analysis, including undertaking a comprehensive study of ESD initiatives in high-rise residential buildings around the world.

We hoped to uncover projects that would serve as a blueprint of sorts, but our findings were underwhelming. An analysis of 18 current and future tall residential building projects since 2014, spanning Australia, the United States, Asia and the Middle East, found few with environmental certification and most with fairly standard “green” initiatives: double-glazed facades, natural ventilation of apartments, regenerative lifts, external shading, energy efficient whitegoods and green walls. Less common features included rainwater harvesting, heat recovery systems, smart meters, and the elimination of fossil fuel generated energy.

Creating a sustainability framework

The project team went back to first principles and looked at key sustainability initiatives appropriate to the Sydney CBD location and climate leading us to a design incorporating the following initiatives:

  • high-performance facade with clear glazing, external shading and innovative natural ventilation system, improving energy consumption and thermal comfort and reducing noise.
  • significant green spaces (two sky gardens within the tower, a roof garden and green walls) contribute to the city’s biodiversity and connect residents to nature
  • trialling a shower heat recovery technology which pre-heats cold water supplied to shower heads, reducing the amount of hot water required
  • connection point to the recycled water pipe infrastructure installed in George Street to allow use of recycled water in the future for non-potable uses when the precinct recycled water system becomes operational
  • secure bike storage and easy access to nearby public transport
  • charging points for electric cars in five per cent of car parking bays with the option to increase this number to meet future demand
  • during detail design phase, we will investigate the feasibility of the infrastructure required for future installation of batteries, should they become viable in high density buildings
  • A hybrid domestic hot water system comprising heat pumps for base load and natural gas boost. As technology develops (both in efficiency and size) it is proposed to replace the gas boost system with heat pumps in the future to make the building fully electric
  • No natural gas provided to any apartment. Cook tops will be induction type. To make this possible, Arup’s services engineers had to analyse in detail the peak electrical loads to stay within the capacity of the site’s two sub-stations.

Future-proofing for zero carbon

The elimination of natural gas from apartments and the reduction of gas elsewhere represents a significant milestone in Australia’s cities. This will enable the building to run on low carbon electricity as the grid decarbonises or 100% renewable energy by entering into a future Power Purchase Agreement (PPA).

505 George Street will become Australia’s tallest residential tower to receive a 5 Star Green Star Design and As-Built rating from the Green Building Council of Australia. The building will exceed the BASIX (Australia’s Building Sustainability Index) minimum targets for water and energy and is future proofed to become zero carbon.

Already, this project is making waves. In 2019, it won the MIPIM Architectural Review Future Project Award in the Tall Buildings category in Cannes, France and was named a finalist in the best future residential projects at the World Architecture Festival.

Like 1 Bligh Street, 505 George Street belongs to a rare class of building whose elegance is inextricably connected to a high-performance function. To achieve our high ambitions, the entire design team, with great support from the clients, hope that by future proofing the building and defining new benchmarks in the residential market, 505 George Street becomes a landmark project in these times of change.


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