Embodied carbon in buildings: a new frontier in greenhouse gas reduction

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SNSW Sydney

In October this year the new Sustainable Buildings State Environmental Planning Policy will require architects and developers in NSW to start measuring the embodied carbon in their designs as Australia seeks to transition to a low-carbon built environment.

Associate Professor Philip Oldfield, head of UNSW’s School of Built Environment in the Faculty of Arts, Design & Architecture, explains the dilemma faced by professionals working in the built environment.

“Every square metre we build has a carbon footprint, and that can be quite high, because the materials we rely on to construct buildings are very carbon intensive. But we can’t simply stop building. We have a social obligation to provide healthy, comfortable, safe and sustainable places for people to live, to work and to play, around the world,” says A/Prof. Oldfield.

“So, a key question for people working in the built environment is how can we build while ensuring new construction has the smallest possible impact on the environment?”

What is embodied carbon?

Embodied carbon is the greenhouse gas emissions associated with creating a building, maintaining it over its life, and eventually demolishing the building. “In a nutshell, it’s the greenhouse gas emissions associated with extracting and creating materials, and construction and deconstruction. And that’s different to ‘operational carbon’ which is the emissions released through the operation of the building, air conditioning, heating, cooling, lighting, plugging in your computer.”

The Australian construction industry is responsible for 18.1 per cent of our national carbon footprint, or more than 90 million tonnes of greenhouse gas emissions every year. Twenty years ago, the thinking around the carbon footprint of buildings was that operating CO2 was about 80 per cent of the building’s emissions, while embodied CO2 was maybe 20 per cent. So the focus when reducing a building’s greenhouse gas emissions was all about making it more energy efficient, and embodied emissions were generally ignored.

“The greenest building is the one that already exists.”

“We have relatively mature building regulations focused on reducing operating emissions,” explains A/Prof. Oldfield. “But there are very few regulations concerning embodied emissions anywhere in the world. But the thinking about the relative importance of embodied emissions has changed as we’ve got more energy efficient, and become better at measuring embodied carbon. So, for any new building constructed in Australia today, we expect at least half of its total carbon footprint over its life will be embodied carbon, possibly even more.”

The World Green Buildings Council (WGBC) has set a target for all new buildings to be net zero operationally by 2030. What this means is the carbon footprint of our buildings will effectively be all about embodied carbon. This necessitates a big shift in the thinking about how we create sustainable buildings.

This challenge is made more difficult in the context of a growing world population and increasing urbanisation. Due to this, we are currently constructing the equivalent to every building in Japan every year. That is a lot of concrete, a lot of steel and a lot of embodied carbon. The challenge is how can we build to meet the needs of a growing society, while also reducing these environmental impacts.

The WGBC has set two targets around embodied carbon. The aim is for all new buildings, infrastructure and renovations to have at least 40 percent less embodied carbon by 2030 and to reach ‘net zero embodied carbon’ by 2050.

Photo: Adam Monk.
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