Plans for a third runway at Heathrow Airport have been ruled illegal by the Court of Appeal because they do not take into account the UK’s climate change commitments.

In the 2015 Paris Agreement on Climate Change the UK pledged to achieve zero carbon emissions by 2050. Last year, Parliament voted to make this pledge a legally binding commitment. Whilst the Court ruling is a serious setback to Heathrow’s expansion plans it is also a wakeup call to the construction, engineering and landscaping industries to take more account of our nations carbon reduction commitments in project planning and the materials they choose and use.

Getting to grips with how the zero carbon commitment can be achieved is an increasing priority. This is where wood comes in. The UK timber industry believes wood should play a key part in any plans to tackle climate change. This is a view endorsed by the All-Party Parliamentary Group for the Timber Industries which published a report in November last year urging the Government to implement the recommendations of the independent Committee for Climate Change by increasing the use of wood for construction, structural engineering and landscaping applications.

The WPA believes that making the most of wood to tackle climate change goes hand in glove with making the most of wood protection technology. In this article WPA Chief Executive Gordon Ewbank explains why.

Compatibility with zero carbon emission goals

Wood’s sustainability, carbon storage ability, low-embodied energy production and sheer versatility make it a standout choice as a construction and landscaping engineering material. The ability to enhance its durability and performance using wood protection technologies adds significantly to its versatility and efficiency.

The climate change crisis and depletion of fossil fuels and the raw materials for man-made materials like steel, plastic and concrete is re-focussing government strategy on circular ‘bioeconomic’ principles using renewable biological resources. Wood is part of this circular bio economy. Unlike manmade materials which are produced from finite raw material sources (once gone they’re gone for good), timber can be harvested indefinitely under sustainable forest management schemes. The more wood is used the more trees are planted. The benefits to the environment are substantial. A growing tree absorbs the gas most associated with climate change, carbon dioxide (CO2) and stores it as carbon within its mass while releasing life-giving oxygen into the atmosphere.

When the tree is harvested and converted into a wood product the carbon remains locked in the product for its service life. By extending the service life of wood with a preservative or wood modification process that carbon is stored for a significantly longer time. However, the most effective way to use treated wood in a CO2 reduction strategy is use it in place of more ‘carbon intensive’ man made materials. The European confederation of woodworking industries, CEI-Bois, has calculated that the substitution of 1 cubic metre of concrete with the same volume of treated wood will save CO2 emissions to atmosphere by 1.1 tonnes. If this saving is added to the 0.9 tonne of CO2 already locked into the wood, then by substituting treated wood for a man-made material will prevent the emission of 2 tonnes of CO2.

Another important statistic in support of wood is The International Institute for Environment & Development calculation that it would take just a 10% increase in the number of houses in Europe whose main structural components are wood to reduce CO2 emissions equivalent to around 25% of the global reductions prescribed in the Kyoto Protocol which came into force in 2005. Clearly, the climate crisis has moved on since then but the point about the contribution that wood and long- lasting treated wood can play is still relevant to the binding commitment made by UK under the Paris agreement.

A recent study by BRE Centre for Sustainable Products further underlines the value of treated wood in tackling climate change. The study found that a terrace made from preservative impregnated softwood had a global warming potential 200% lower than a terrace made from concrete slabs and 700% lower than composite plastic decking.

BRE has several publications dealing with how different design and material choices impact the environment such as the influential ‘Green Guide to Specification’ and ‘BREEAM’ the world’s leading sustainability assessment method for infrastructure and buildings. These key documents share some key conclusions about treated wood. The first is that wood protection processes are so insignificant a factor overall as to not alter a functional unit’s environmental impact rating regardless of whether it is treated or not. The second is that the use of chemically treated softwood in both structural and non-structural elements does not undermine the very strong environmental case for using wood in construction.

In true circular bioeconomic principles, when treated wood products have fulfilled their design service life they can be recovered, recycled into other applications or used in a biofuel plant to generate heat and power.

Weather extremes favour treated wood

A warmer, wetter more extreme climate for the UK is now inevitable according to Defra’s Climate Projections. An increase in temperature and rainfall will heighten the potential for fungal decay and insect attack in components made from un-treated softwoods of low natural durability. Roofing timbers exposed to wetting from leaks are particularly vulnerable. Almost every stick of softwood currently used in roof construction today is untreated. When it costs just £40 to pre-treat the wood in a typical house, the continued use of unprotected wood seems increasingly unwise.

The Climate Change Act 2008 demands that public and statutory organisations take action to adapt to the more extreme weather patterns predicted by Defra. The British Standards Institution (BSI) has identified thirteen potential climate change impacts on standards that need to be addressed if a building is to have a long and useful life. These impacts will increasingly feed through to materials standards in the construction sector. The good news for wood is that for all end-use applications its durability can be raised using wood protection technology. This will help to deliver climate change objectives and eliminate the cost and environmental impact of remedial treatment, early disposal or replacement part way through a structure’s service life.

Strategic opportunities for treated wood

Preservative pre-treatment and modified wood technologies make it possible to use lower cost, low durability softwoods in a wide range of construction applications that would otherwise not be possible. The use of wood protection technology to deliver products with a predictable service life justifies the use of wood in the face of competition from less sustainable man-made materials.

Until now, wood protection processes have been largely viewed as optional insurance against the risk of wood decay or insect attack. But as the government’s zero carbon strategy begins to gather traction and British Standards take account of climate change predictions, pretreated wood is likely to become a standard requirement for many timber construction applications.

Influencing the Government to include the greater use of wood is now a key priority for the timber industry and WPA is committed to ensuring the benefits of wood protection technology and treated wood are part and parcel of the UK’s CO2 reduction strategy. The time for treated timber is now!

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