A constructive look at tackling building emissions

With awareness being raised this week around embodied carbon in the built environment, Leigh Stringer looks at how the construction industry could potentially become a leader in low-carbon innovation.

The global green and sustainable building industry is forecast to grow at an annual rate of 22.8% between now and 2017

The global green and sustainable building industry is forecast to grow at an annual rate of 22.8% between now and 2017

Accounting for 40% of the UK's total carbon emissions, the construction industry is a particular focus of the Government in achieving carbon reduction targets. Taking note of its significant impact, the Government has set a 50% reduction in greenhouse gas emissions for the industry by 2025, and an 80% carbon reduction by 2050.

A significant challenge when you consider that the UK construction industry is the nation's largest consumer of natural resources, using more than 400 million tonnes of material every year. Putting this into perspective, concrete, the industry's focal material, is estimated to produce 8% of global carbon emissions.

And it is this high carbon, high material use that has got the Government, industry and material experts debating how it can best drive sustainable growth while reducing its monumental impact on the environment and society.

Many in the industry are attempting to tackle this by driving innovation and developing alternatives. For example, the Institution of Civil Engineers (ICE) says a promising new alternative to Portland cement has emerged over the past decade in the form of reactive magnesium cements, which could potentially capture carbon.

It says this naturally occurring magnesium carbonate is heated to just 750 C instead of, in the case of Portland cement, heating limestone to 1,450 C, which both releases and creates a significant amount carbon dioxide. More importantly, magnesium carbonate sets and hardens by taking carbon dioxide out of the atmosphere.

Though recent production trials of these concrete blocks in the UK have moved this towards commercial reality, the new 'green' material is still very much at the research and development stage, according to the ICE. It is clear, however, that these innovative materials are on the horizon, particularly as demand for materials with less environmental impact grows.

The Government's industrial strategy, Construction 2025, says the global green and sustainable building industry is forecast to grow at an annual rate of 22.8% between now and 2017 - a result of increasing low carbon regulatory requirements and greater social demand for greener products.

Until these innovations hit the market though, the construction industry needs to start its transformation through available means. Wood for Good project director David Hopkins says the industry has the ability of creating massive change through the adoption of three initiatives.

"What are the big wins for reducing embodied carbon in materials? For me there are three big wins, and I don't think I'm alone if you ask construction professionals.

"One is the reuse of steel. And that's not recycling, as recycling steel uses a lot of energy. You have to melt it down and then reform it, which is a carbon intensive activity. But steel is very useful so if we can reuse it then that would be a massive win in lowering carbon emissions.

Hopkins says the second is accelerating low carbon concrete. "Concrete is one of the biggest polluters, responsible for around 8% of global carbon emissions and it's the second biggest user of water. So if we use low carbon concrete, which does exist, that would be a big win in lowering real emissions and embodied emissions from construction.

The third is a greater use of sustainable, certified sources of timber. According to Hopkins, there has been a lot of innovation in the development of structural timber materials, which he says are now taking their chunk of market share away from concrete, in particular concrete blocks.

"There are now the opportunities for urban construction to use timber, not just for sustainability reasons but timber is much lighter weight so you don't need the same level of foundation in urban areas. Almost all timber products get manufactured offsite in factories and they're produced to high levels of precision and delivered to the building site nearly assembled which means building time is much quicker. You have these big buildings going up in half the time.

"The official figure is around 30% faster than alternatives. And this of course saves a lot of money. Building sites are also a large imposition to residents and communities and so if the construction project time is shorter there is less inconvenience to people," he added.

According to the UK Green Building Council, the embodied impacts of a project are often measured and reported in different ways and it is becoming clear that industry needs to be joined up around how measurement is approached.

UK Green Building Council chief executive Paul King said: "As industry is increasingly getting to grips with operational energy and the carbon and cost savings that result from reducing it, the issue of embodied carbon has taken something of a back seat.

"But there are progressive businesses out there that recognise both the huge financial and environmental rewards of tackling embodied carbon throughout the various stages of the building lifecycle," he added.

Embodied Carbon Week is taking place from 7-11 April

Leigh Stringer is the energy and sustainability editor for edie.net and Sustainable Business


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