Banking on a zero carbon future

A new campaign highlighting the green credentials of timber as a construction material is bringing a whole new meaning to the term carbon footprint

Wood for Good’s recently launched ‘Build with Carbon’ campaign aims to demonstrate how increased timber construction can act as an effective emissions reduction and carbon storage mechanism, while helping to meet social need and driving vital investment into our forests.

According to new research from the timber industry’s sustainability campaign new-build homes in the UK could be effective carbon ‘banks’, capturing and storing nearly 4 million tonnes of CO2 every year if housing targets were met through timber-frame construction.

Trees absorb carbon dioxide from the atmosphere through the process of photosynthesis, storing the carbon and releasing the oxygen. The carbon is stored thereafter in wood products and research shows that roughly one tonne of carbon is stored for every metre cubed of timber used.

As Wood for Good’s executive director David Hopkins explains: “The carbon is stored in the tree and then in the timber product. They represent carbon emissions which have been sequestered from the atmosphere and stored right there in the physical form of timber. So you could look at pieces of wood/timber and timber products/buildings as representations of sequestered carbon.

“The whole phrase ‘Build with Carbon’ is to put a bit of a spin on people’s ideas of carbon emissions and what they are and where we can put them and what we can do with them. We are saying instead of pumping those carbon emissions into the air let’s safely store them and build with them and use them productively.

“We aim to illustrate the benefits the timber supply chain can bring to the climate debate to encourage the construction industry and policy makers to start building with carbon, rather than emitting it.”

The campaign is supported by a series of video animations produced by data-visualisation experts Carbon Visuals, illustrating the carbon captured in one tree, a hectare of forest, one house and a typical estate. They visualise one tonne of carbon dioxide at normal atmospheric pressure as a 33ft wide sphere, with the CO2 stored in 200,000 three-bedroom homes forming a pile of carbon dioxide spheres far taller than the buildings of Canary Wharf.

The animations show that an average three-bedroom, timber-framed house sequesters and stores roughly 19 tonnes of CO2, meaning that if the UK was to reach the Labour party’s aspiration of building 200,000 homes per year – using timber frame methods – an additional 3.81million tonnes of CO2 would be locked away every year.

“Of course, not all housing needs will be met through building three-bed semi-detached housing as modelled in this study,” says Hopkins. “There will be far greater variety of building types particularly in dense urban areas but our animations illustrate what can be achieved and more.”

The figures were calculated using the Wood for Good Lifecycle Database. This data shows that all timber products studied have a carbon negative footprint – i.e. they have absorbed and stored more carbon dioxide than has been emitted in the supply chain through harvesting, kilning, processing, manufacture and transportation.

“Building with timber is the safest and cheapest form of carbon capture and storage available,” says Hopkins. “We estimate it costs roughly £25-30 per tonne of CO2 captured and stored using mixed woodland forestry. In addition, by storing emissions in buildings you are turning a polluting liability into an asset. Carbon emissions can be accounted for in property, on balance sheet, as an appreciating asset. That has to be better than pumping them into the North Sea.

“Using timber in long-life applications such as buildings means more trees will have been planted, grown and harvested before the timber product reaches its end of life. This provides for an emissions reduction and storage mechanism – with more carbon emissions being added to the store in each harvesting and each new building.”

High sequestered carbon, timber products also require very low energy input for production compared to other mainstream building materials giving them very low embodied carbon values –a fact that will see it playing a lead role in meeting the zero carbon homes standard says Hopkins.

“All timber products represent carbon emissions which have been sequestered and stored – acting as a physical carbon market not a derivative one. We need to encourage the trade in this physical carbon market and in so doing drive investment back into our forests.

“Trees grow naturally just using sunlight and water, you don’t have to have a big jolt of electricity or anything and then the actual manufacturing process, the processing and the harvesting and everything else and then making a timber frame is very very low energy compared to firing bricks or smelting steel or churning concrete. So you get the same performance as any of the other construction products for far lower energy input.

“Yet despite this, the majority of UK housing continues to be delivered through carbon intensive building methods.”

Timber has long been a material of choice north of the border in Scotland where 70% of new-build homes have timber frames while in England the material accounts for just 15% of the market share, although this figure is growing and is predicted to rise to about 20-25% over the next few years.

“As the housing market has been slightly unleashed again developers are seeing a need to build quickly and there is a bit more of a churn in the market through incentives such as Help to Buy, more and more developers are turning to timber frame to deliver their projects more quickly,” explained Hopkins.

“[Timber is] naturally low carbon so the increase in the manufacturing base across the whole timber industry doesn’t come with huge increases in emission and energy demand which it does in all other sectors if you have an upturn in brick production or steel or car production or any other sector it also comes with a huge surge on the power demand. Timber is a very low energy input system so you can have big economic growth without huge energy demand and emissions output.”

The timber sector employs about 150,000 people directly through the supply chain, not to mention supporting jobs in markets that feed into it. Further development of the sector would be a boost to the economy and would drive investment into forests – vital if more buildings are to be constructed using timber frames.

“It drives a lot of investment back into our forests so it is like a virtuous circle really as we are only ever going to use sustainably grown materials which means for every tree cut down a couple more are planted. It drives investment back into those with all of the biodiversity and eco system and ecological services that they provide,” said Hopkins.

According to the Confederation of Forest Industries (Confor), wood supplies are set to peak around 2025 posing a challenge to future supply as well as the potential loss of a valuable carbon bank. Yet an increase in the UK’s forest cover from 13 to 16% could reduce around 10% of the UK’s national CO2 emissions by 2050 and provide the feedstock for a vibrant manufacturing industry.

One of the challenges now, Hopkins explained is to gain recognition of timber’s role in the low-carbon supply chain and to access finance to grow the sector.

“I think the timber sector needs to be recognised by institutions like the Green Investment Bank so that it is seen as a truly low-carbon industry,” he said. “A lot of the work that we have done with the lifecycle assessment and the Build with Carbon side is to show that this is an emissions reduction mechanism and needs to be recognised as such and it should be able to access those areas of finance to fuel its growth.

“The recognition of the timber industry as a low-carbon supply chain would be very good in unlocking a range of different areas of finance and in encouraging more timber development.”

This article first appeared in the Winter 2014 edition of Timber & Ecoconstruct magazine