We’re building a New York-sized city every month. That’s worrying for our climate

Philip Oldfield, William Craft, UNSW

Each of us needs of a roof over our head, classrooms to learn in and offices or space to work from.

To meet this unprecedented demand for new buildings, globally we’re constructing the equivalent of an entire New York City every month.

This provides us with vital infrastructure, but also generates an enormous amount of world-warming emissions.

So how can we build what we need, without harming our planet? Our new research provides some answers.

The need to build

Creating new buildings benefits communities, cities and countries, and eases housing pressure. That’s why Australia’s National Housing Accord is aiming to construct 1.2 million new, well-located homes between 2024 and 2029.

But this Australian effort is dwarfed by the 96,000 new and affordable homes needed worldwide every single day. Tragically, hundreds of millions of people around the world endure homelessness. One in four are living in harmful conditions.

However, construction comes with a climate cost. Each time we build, we use materials and construction processes that release large amounts of greenhouse gas emissions – known as “embodied carbon”.

To understand the scale of embodied carbon, picture a square metre of floor space. Constructing that square metre would release around half a tonne of greenhouse gas emissions. Now scale that up to building a whole New York-sized city every month!

What we studied

Our new study examined trends in office building construction in Australia. We currently have about 170 million square metres of office space across the country, and are set to build a further 100 million square metres by 2049.

To investigate what effect these buildings have on global warming, we modelled their greenhouse gas emissions. We measured both their embodied carbon and operating carbon – the emissions from everyday heating, lighting, cooling and appliances.

We found Australian office buildings are projected to release 138 million tonnes of greenhouse gas emissions between 2024 and 2049. This number is equivalent to the annual emissions of 36 coal-fired power stations. Given offices make up just 20% of all commercial buildings in Australia, this is only a fraction of our total urban emissions.

Read more: How low can we go? To cut the carbon that goes into buildings to net zero, we need radical change

A mixed picture

Most surprisingly, operating emissions represented 85% of the total in 2024, but are set to drop to just 15% by 2049. This is because Australia is decarbonising our energy sector by shifting from fossil fuels to solar, wind and other renewables.

However, if we keep building at our current speed and scale, our annual embodied emissions will remain at similar levels. Compared to operating emissions, it’s more difficult to lower embodied carbon because many material supply chains rely on fossil fuels and carbon-intensive practices. The process of manufacturing cement, for example, is responsible for 8% of all global carbon dioxide emissions.

We also compared office building emissions in Australia with emission pathways that would limit the sector’s contribution to global warming below 1.5°C or 2.0°C. However, we found cumulative emissions from offices are over 40% above these pathways. This means office buildings will likely blow their carbon budgets within a matter of years. We found Tasmania – which runs almost entirely on renewable energy and has fewer office buildings per capita – is the only state or territory with annual emissions that sit consistently below the 1.5°C pathway.

Cutting carbon

Our study measured several ways to reduce embodied carbon in office buildings, summarised below:

We found combining these strategies could reduce total emissions by over 47 million tonnes, putting the office sector far closer to the 2.0°C emissions pathway target.

These results show the importance of “sufficiency” measures, such as refurbishing existing buildings and constructing smaller, or fewer, new buildings.

Research shows sufficiency strategies work. Consider Sydney’s Quay Quarter Tower. This tower was originally built in 1976 but, by the late 2010s, was older and less useful. Rather than demolish it, architects 3XN and BVN extended the tower to the north and upcycled two-thirds of the original structure. This increased office space while saving around 8,000 tonnes of embodied carbon.

More work ahead

Our study suggests embodied carbon will, in the next decade, overtake operating carbon as the leading source of building emissions. This is problematic because most countries don’t impose limits on embodied carbon. As a first step, Australia must regulate embodied carbon emissions as other countries – including Denmark, Finland, France, the Netherlands and Sweden – have already done.

We should also offer incentives for the construction sector to refurbish older buildings. Several councils in the United Kingdom have adopted “retrofit first” policies, where builders must at least consider options for refurbishing buildings before simply demolishing or replacing them.

Our ever-growing global population demands millions of new homes, workplaces and community spaces. But to truly tackle climate change, we must find better ways to balance society’s need for new space with a commitment to curb emissions.

Read more: Why knock down all public housing towers when retrofit can sometimes be better?

This article is republished from The Conversation under a Creative Commons license. Read the original article.