If asked to consider how to cut carbon emissions, most people would probably focus on reducing energy use in their home or place of work, or opting for renewable energy sources to achieve goals.
What many may forget are the emissions created during the manufacture, transport, maintenance and disposal of materials used to construct our homes, offices, public buildings and infrastructure – plus the whole engineering of things.
As Australia is in the grip of a construction boom, where we are actually increasing carbon emissions via such activities, the materials manufacturing process and the design and engineering of new buildings are issues we need to think carefully about.
There is probably not a lot we can do about the low carbon targets of current urban development projects, now approved and underway, although some will have star rating goals. However, if we are to achieve our greenhouse gas reduction targets of 25 per cent by 2020 and 80 per cent by 2050, more action is required, sooner rather than later.
Every area where emissions occur must be improved – not just lowering carbon released from building operations, but also during the carbon-intensive cradle-to-grave construction process, known as ‘embodied emissions.’ In this process, the recycling and disposal of materials when a building is demolished also play a key role.
In their 2010 paper Redefining Zero, authors Simon Sturgis and Gareth Roberts noted that the typical life-cycle of carbon emissions in a modern commercial building has 55 per cent attributed to building operations and 45 per cent to embodied emissions.
This figure for embodied emissions shows the need for you to reflect on the steel, concrete and power it took to create the building, the street, train station or tram stop where you are. In addition, think about the diesel used and carbon emissions produced to transport the materials when the buildings is demolished. They all count.
Then consider this: the highest carbon emissions created during the manufacture of building materials comes from steel, cement and aluminium. In the UK, for example, cement and steel are responsible for more than 40 per cent of all industrial carbon emissions. Cement manufacture is also responsible for five per cent of total global anthropogenic carbon emissions – more than even the aviation industry.
All these materials do have their benefits. For example, steel is good for recycling after demolition, though full comprehensive documentation of all the pros and cons is needed.
There are several ways to address the reduction of embodied carbons, starting with the energy source used to produce materials in the manufacturing process. As mentioned above, the recycling and reuse of materials during construction is important as this minimises the need for new materials, therefore decreasing emissions, whilst clever design and engineering can maximise floor and ceiling space.
Another approach is the adaption of the current practice of Value Engineering (VE), where cost reductions and how a building is constructed are optimised before work begins. This typically involves dematerialisation, reducing the resource needs of a building. This process could embrace embodied carbon reductions into the equation.
This is a challenge currently being researched, so the whole life cycle carbon in a building can be considered. Ultimately data will have to be collected to develop a tool to track carbon along the production of supply chains, to reflect the carbon outputs of industry and map their affects across Australia.
We can also go back to basics and increase the use of a natural building material mankind has used since making shelter began – timber.
A great example of wood being used in modern construction projects with low carbon goals is the Barangaroo development in Sydney, where plans for a second wood based building are now on public display. This is not ‘raw’ wood but a hybrid of laminated timber and glulam – or glue laminated timber. If approved, this seven-storey building would be a ‘sister building’ to the award-winning International House, which is Australia’s first engineered timber office building.
UK architectural designer Dr Philip Oldfield is a great fan of timber. He is currently in Australia to conduct research into high-rise architecture and embodied carbon and is writing a book, due for publication next year called The Sustainable Tall Building and is happy about the current timber renaissance.
“Timber has much lower levels of embodied carbon compared to say steel or concrete, which reduces its impact on the environment. Ultimately using them in buildings can make them sustainable powerhouses,” he said.
Oldfield explained that this new laminated timber is extremely strong and can even be protective in fire. Whereas unprotected steel loses its structural strength and can fail at high temperatures of 550 Celsius or more, mass timber products can be designed to char like trees in forest fires, thus providing inherent protection and allowing people to escape.
“There are therefore many advantages to timber; not only does it act as a carbon sink and provide a natural aesthetic, but it adds an extra level of safety to a building,” he said.
Ultimately, timber could not only bring engineering benefits; it also offers business and environmental opportunities. Should demand for timber rise through sustainable building practices, more wood needs to be grown exclusively for these purposes, which means that during the growing process, oxygen is released into the atmosphere and carbon dioxide absorbed.
The forestry industry can therefore play an important role in assisting in a low carbon future and economy. For example a United Nations Food and Agriculture organisation report recently said:
“Forests are at the heart of the transition to low-carbon economies. Forests and forest products have a key role to play in mitigation and adaptation, not only because of their double role as sink and source of emissions, but also through the potential for wider use of wood products to displace more fossil fuel intense products.
“Indeed, a virtuous cycle can be enacted in which forests increase removals of carbon from the atmosphere while sustainable forest management and forest products contribute to enhanced livelihoods and a lower carbon footprint.”
The report also found that the use of wood products in Australia has declined and reversing this trend would have positive effects.
All in all, we still have several more steps to take, but it is clear, there are many opportunities to be had in the low carbon engineering of things.