What does Australia need to green our cities by 2030?

Nine years later, Australia and the wider international community have made significant improvements in carbon emissions. At the time the Paris Agreement was signed, global carbon emissions were projected to increase 16 per cent by 2030, but now the projected increase by 2030 is just 3 per cent.

However, as managing director of Boon Edam Australia Michael Fisher warns, this projected increase is “not good enough”.

“Predicted greenhouse emissions still must fall by 28 per cent for the Paris Agreement’s 2˚ C pathway and 42 per cent for the 1.5˚ C pathway,” said Mr Fisher.

One major stumbling block for Australia in particular is the growth of our nation’s built environment. Currently, the built environment accounts for nearly 40 per cent of all global carbon emissions.

In Australia, existing commercial buildings are responsible for nearly 24 per cent of the nation’s total annual electricity consumption, according to research from the Department of Climate Change, Energy, the Environment and Water.

“As Australia’s stock of non-residential buildings surges past a million for the first time in its history, energy experts are looking at ways to reduce the power consumption of both new and existing commercial buildings,” said Mr Fisher.

By 2030, Australia has committed to reduce greenhouse gas emissions by 43 per cent below 2005 levels, according to the 2022 Nationally Determined Contribution (NDC) submitted to the UN.

In addition, Australia has committed to net zero emissions by 2050.

As mandatory climate reporting deadlines loom, Australian developers of commercial and high-density residential buildings may increasingly turn their attention towards the building envelope in a bid to reduce emissions.

“Heating, ventilation and air conditioning (HVAC) systems account for up to 50 per cent of a commercial building’s energy use and dominate peak electricity demand,” said Mr Fisher.

Tightening the building’s envelope through high-performance glazing, improved building insulation and external window shading could significantly reduce the need for energy-intensive HVAC systems.

“High-performing envelopes – the parts of a building that separate the indoors from the outdoors – are the most effective way to reduce the thermal needs of buildings,” said Mr Fisher.

He emphasised the importance of “tighter building envelopes that don’t leak expensively cooled or heated air”.

“Can we afford to ignore a scientifically validated individual solution to energy savings?” Mr Fisher asked.

Another option that cities are increasingly turning to for improved thermal performance is green roofs.

Recently, researchers from the University of New South Wales (UNSW) and Kyung Hee University in South Korea partnered up to assess the impacts of green roofs on cooling Seoul during the height of summer.

The results were promising: according to the researchers, green roofs have “tremendous potential to substantially decrease the peak temperature of a city and increase energy savings”.

Professor Mattheos Santamouris from UNSW explained: “One of the major problems in the built environment worldwide is severe urban overheating.”

“As our cities heat up, thermal discomfort and heat-related illness and death also rise,” Professor Santamouris said.

The research team found that when 90 per cent of buildings were covered in one of the cheapest kinds of green roofs, air temperatures in Seoul dropped 0.5˚ C while the surface temperature dropped by 2˚ C. Building energy use also decreased by almost 8 per cent.

”There is an urgent need to implement a combination of heat mitigation techniques and technologies in our cities to decrease urban temperatures,” Professor Santamouris said.

“If we do not, the cost in the coming decades will be catastrophic, not just for the economy, but on quality of life, particularly for low-income populations who will suffer the most.”