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Talking Point

Sustainability must be considered at the design stage if environmental targets are to be met, says Viv Troughton.

The pressure to reduce our environmental impact is driven by a number of factors.

Most significantly the UK government has set the industry a series of ambitious environmental targets, including cutting construction, demolition and excavation waste
sent to landfill by half over the next two years and building zero-carbon non-domestic buildings by 2019. Consequently, the expectations on clients, developers, contractors and the supply chain to become more sustainable are greater than ever before.

What happens below ground is often overlooked by designers when it comes to developing more environmentally friendly structures.

However, if the industry is to dramatically reduce its environmental impact it is crucial that sustainable alternatives are considered from the early stages of a project.

Geotechnical specialists can play a significant role in contributing innovative solutions, provided they are involved from the outset.

This is the time when concrete decisions are made on site formation levels - often quite literally.

For example, at the early stages of a project ground engineers might be able to suggest the use of geothermal energy piles, which will considerably reduce a building’s energy consumption, and consequently its impact on the environment.

Energy piles make it possible to implement ground-source heat pumps cost effectively, replacing the need for bored holes.

This adds value to a standard piling solution as rotary bored, CFA or driven piles can be used to both support the building and also as part of the heat pump mechanism.

Reducing waste sent to landfill such as by re-using foundations is another sustainable approach that is fast gaining ground.

This not only saves on resources but can also save clients money by avoiding the expense of landfill tax and of transporting virgin materials on site.

However, true innovation lies in creating designs that reduce the use of carbon-intensive materials underground.

“Reducing the threat posed by climate change cannot be achieved by one sector or group alone.”

Figures vary, but it is estimated that the global manufacture of cement accounts for 5% of all man-made CO2 emissions, and as much as half of this emitted carbon comes from converting limestone into cement.

Suppliers are now facing increasing pressure to reduce the carbon content of the materials they use by improving manufacturing processes (and using substitutes).

However, this is not as easy as it sounds as surprisingly little reliable data exists on some of the manufacturing processes, such as for steel or concrete.

What is needed is a protocol for the industry to ensure that suppliers provide reliable measures for their processes - and it is only then that targets can be introduced to improve them.

In many cases, ground engineering solutions that are more energy efficient are also cheaper for the client and more profitable for the contractor.

By using Green Siesta, Stent’s carbon calculating tool, we have noticed that there is a strong correlation between sustainability and cost: more often than not, the greener the ground engineering method, the greater the cost savings to the client.

Reducing the threat posed by climate change cannot be achieved by one sector or group alone.

It is a collective responsibility with everyone with a part to play in the construction process - clients, developers, contractors and their entire supply chain - involved at the earliest possible stage of a project.

When that happens perhaps we can look forward to a future where the industry competes on carbon emissions as transparently as it currently does on price and service.

  • Viv Troughton is technical director at Stent - foundations and piling division of Balfour Beatty Ground Engineering.

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