Discover the construction materials contributing most to embodied carbon and explore innovative solutions to reduce the carbon footprint in the industry.
Embodied carbon refers to the total greenhouse gas emissions produced throughout the lifecycle of construction materials. This includes the extraction of raw materials, manufacturing processes, transportation, installation, and eventual disposal. While operational emissions from buildings, such as heating and cooling, have traditionally received the most attention, the embodied carbon in construction materials now accounts for a significant share of the total carbon footprint of new buildings and infrastructure.
As sustainability becomes a paramount concern in the construction industry, understanding and mitigating embodied carbon is crucial. This shift in focus is particularly relevant in light of global efforts to reduce greenhouse gas emissions and combat climate change. By addressing embodied carbon, stakeholders can make more informed decisions that contribute to a more sustainable built environment.
Concrete is the most widely used construction material globally, and this is no different in Australia. Despite its relatively low emission factor of about 0.2 kg CO₂ per kg, concrete's massive usage leads to a significant overall impact on embodied carbon. The high embodied carbon in concrete primarily stems from the production of Portland cement, a key ingredient in concrete. The process of producing Portland cement is highly energy-intensive and generates substantial carbon dioxide emissions.
Given its prevalence in construction, concrete's contribution to embodied carbon is a major concern. Strategies to reduce its impact include the development of alternative materials such as geopolymer concrete, which uses industrial by-products and requires less energy to produce. Additionally, incorporating recycled materials and improving the efficiency of cement production processes can help lower the embodied carbon associated with concrete.
Steel is another major contributor to embodied carbon in construction. With an emission factor of approximately 2.2 kg CO₂ per kg, steel's carbon footprint is substantial. This is largely due to the energy-intensive processes involved in its production, particularly the reliance on coal in blast furnaces. Steel is extensively used in structural elements of buildings, bridges, and other infrastructure, making its embodied carbon footprint significant.
Efforts to reduce the embodied carbon of steel involve exploring alternative production methods, such as electric arc furnaces that use scrap steel and renewable energy sources. Additionally, high-strength steels, which require less material to achieve the same structural integrity, and steel recycling are other promising strategies to mitigate the carbon impact of steel in construction.
Aluminium, while used in smaller quantities compared to concrete and steel, has the highest emission factor—around 20 kg CO₂ per kg—making it extremely carbon-intensive. The primary reason for this high embodied carbon is the electricity demands of aluminium smelting, often powered by fossil fuels. Aluminium's high strength-to-weight ratio makes it valuable in construction, particularly for elements that require both durability and lightness.
Reducing the embodied carbon of aluminium involves increasing the use of renewable energy in the smelting process and enhancing recycling rates. Aluminium is highly recyclable, and using recycled aluminium can significantly lower its carbon footprint. Innovations in smelting technologies and a shift towards greener energy sources are also critical for reducing the embodied carbon associated with aluminium.
The construction industry is actively seeking lower-carbon alternatives and innovative solutions to reduce the embodied carbon footprint of future projects. Geopolymer concrete, which replaces Portland cement with materials like fly ash and slag, offers a promising alternative with significantly lower emissions. Recycled materials, including recycled steel and aluminium, are also gaining traction as they require less energy to produce and reduce the demand for virgin raw materials.
High-strength steels, which allow for the use of less material without compromising structural integrity, are another key innovation. Additionally, advancements in production technologies and a greater reliance on renewable energy sources can help decarbonise the most challenging materials. By adopting these solutions, the construction industry can make significant strides in reducing its overall carbon footprint and contributing to global sustainability goals.