It is an obvious but often overlooked fact that our cities are filled with existing buildings – each one of them with a carbon footprint locked in before anyone steps foot through the front door. But a rare and visionary NABERS-rated building in Brisbane shows how adaptive reuse can save money and time, cut carbon and create a world-class workplace.
Look at Midtown Centre and marvel. It’s hard to believe this modern vertical village was once a pair of identical 20-storey office towers that stood 13 metres apart.
But when Health House and Forestry House went on the market in 2017, Sydney-based financial house Ashe Morgan and DMANN Corporation saw the potential to combine two 1980s buildings to create a 21st century workplace.
In an architectural first, the façades of the two buildings were removed and the building stripped back to a raw concrete shell. Each floor slab was stitched together. Extra storeys were added, bringing the height to 26 floors and yielding an additional 70% net lettable area.
“Traditionally, we would have knocked down both buildings and started again. But by retaining over 50,000 tonnes of concrete and 3,600 tonnes of steel, we could save around 25% on construction costs, while also capturing lifecycle benefits,” Michael says.
View the case study here: Midtown Centre, Brisbane QLD
We saved about $2 million in the social cost of carbon because we kept the building’s structure. The 11,000 tonnes of CO2 saved is the equivalent to removing 2,500 cars from the road for a year or around four years of carbon neutrality.
Fast facts
- The two buildings at 155 Charlotte Street and 150 Mary Street in Brisbane’s CBD are now one 44,000-square-metre, 26-storey vertical village
- With 5 Star NABERS Energy and 4 Star NABERS Water ratings, Midtown Centre is 30% more energy efficient and 35% more water efficient than a conventional building
- A 36% reduction in carbon emissions was achieved when compared to a new build, plus 90% of construction waste was recycled
- A lifecycle analysis of the project’s sustainability credentials found it was 246% more environmentally friendly than a demolition and new build scenario
- A 49% saving on embodied carbon was achieved thanks to the innovative re-use and re-purpose strategies;
- The building's 2,500 sqm campus style floorplates and 1,950 sqm tower floorplates are Covid-responsive, with tenants easily able to accommodate 1.5 metre social distancing with a density of one person per 12 sqm
- 50% additional fresh air supply over the Australian Standards minimum, plus UV filters reduces bacteria and air contaminants by 99.7%.
NABERS as a proof point
The Midtown Centre project was signed up for a NABERS Commitment Agreement in 2017, at the design stage, which put on paper a promise to achieve a 5 Star NABERS Energy rating.
The visionary design and environmental credentials attracted widespread support from the local community and were central to Brisbane City Council’s approval of the development in 2018.
Brisbane City Council is determined to create a world-class, design led city, and at the centrepiece of this vision are the Buildings that Breathe guidelines and Brisbane Green Building Incentives Policy.
Midtown Centre embraces and enhances its natural environment with outdoor spaces that give back to the city. The laneway that now connects Charlotte and Mary streets, the large floorplates with abundant natural light, the three naturally ventilated atriums and the iconic Level 20 sky garden all align with the planning aspirations of Brisbane City Council’s Buildings that Breathe philosophy.
NABERS undoubtedly steps into the spotlight when developers are in conversation with potential tenants, Michael said.
“When I’m marketing to tenants, I always bring it back to the financial metrics by comparing a standard building that doesn’t have a 5 Star NABERS Energy rating to one that does.”
The 30% energy and 35% water savings at Midtown Centre have a true, tangible benefit for the tenant. With a NABERS rating it is easy to quantify these outgoings.
Why embodied carbon emissions loom large
NABERS Energy measures – and then helps building owners manage – operational emissions. But the sum of greenhouse gas emissions released during a building’s lifecycle has been, until now, a hidden issue.
The term ‘embodied carbon emissions’ refers to those generated from raw materials extraction right through to demolition and disposal. Most of these emissions are locked in before a building is occupied. The World Green Building Council estimates that embodied emissions are responsible for 11% of the built environment’s global carbon footprint.
As building operations become more efficient, embodied emissions loom larger. The Green Building Council of Australia has found that embodied carbon was responsible for 16% of the nation’s built environment emissions in 2019. But we can expect this share to hit 85% by 2050.
NABERS is currently working in partnership with industry and governments across Australia to develop a framework for embodied carbon that will help project teams to measure, set targets, compare and verify upfront emissions of new buildings.
The next step on the road to net zero
Many tenants have publicly declared their net zero ambitions – and a natural next step is to scrutinise the footprints of their buildings.
“We are entering this new phase where net zero operational emissions can be achieved through good design, smart operations and with the purchase of offsets and green power. But a significant contributor to lifecycle emissions is the embodied carbon, which is why the adaptive re-use of Midtown Centre is such a great sustainable story,” Michael says.
The Midtown Centre project was 25% more cost effective and 30% more time efficient because we didn’t have to demolish the existing building.
A reimagining at the scale of Midtown Centre depends on ‘good bones’ – something that not every building can boast. “Adaptive reuse is limited by the physical constraints,” Michael says. But when the formula is right, the rewards are spectacular.
Concrete and steel – which generate around 8% of global construction emissions apiece – are carbon-intensive materials. But Midtown Centre has retained more than 50,000 tonnes of concrete and 3,600 tonnes of steel from the two old towers, which reduced its carbon footprint by 11,000 tonnes of emissions.
Not every building is ripe for reimagining and encouraging more adaptive reuse will require fresh thinking from planners, regulators and industry, Michael adds.
“Because you are retaining the structure, it should inherently be 20%-25% more cost effective to readapt an existing building. But in a ‘hyper-escalated’ contracting market the numbers become more challenging,” he says.
Michael has an acronym for what has been achieved at the Midtown Centre – PER, or “purposeful, enriched re-creations”.
“Purposeful, because we must think carefully about what we are doing. Enriched, because the process adds quality and value. And re-creation because we are re-imagining the entire proposition of what a building could be.”
View the case study here: Midtown Centre, Brisbane QLD