Not a day goes by when the topics of climate change, reducing carbon emissions, and living in a more sustainable manner are not discussed. A quick Google of ‘net zero’ returns more than 1.5 billion results. But how can building with timber help us to achieve our net zero goals?
While it is clear that governments, companies and individuals need to make substantial changes to halt climate change, there remains some confusion about the role of forests, woodlands and timber in helping us to achieve this aim.
How does using more wood in construction help?
Isn’t the most important thing to improve insulation and switch to using renewable energy?
If we need to plant more trees, why are we then cutting them down for building materials?
We'll admit, it can seem pretty confusing.
According to the UK Green Building Council, the built environment accounts for 40% of all the UK’s carbon emissions. Acknowledging the built environment’s responsibility in this area, the construction industry and government alike are looking for the best ways to meet the 2050 goal.
In March, the Environment Audit Committee launched an inquiry into sustainability in the built environment and reaching net zero. The UK timber industry has responded, calling on the government to take stronger action to reduce embodied carbon emissions through policy. The response outlines the significant role wood has to play in helping to decarbonise the structural fabric of new and existing homes and the construction industry as a whole. Evidence sessions are expected to start in July 2021 with a report to follow.
Within the built environment, government policy to date has focused primarily on reducing energy use in buildings (known as operational carbon), rather than embodied carbon (the amount of energy used in the creation of building products and to construct a building).
According to the UK Green Building Council, operational carbon emissions are those associated with energy consumption (operational energy) while the building is occupied. This includes the regulated load (e.g. heating, cooling, ventilation, lighting) and unregulated/plug load (e.g. ICT equipment, cooking, refrigeration appliances).
The government’s 2017 industrial strategy included the Clean Growth Challenge which led to a mission to at least halve the energy use of new buildings by 2030.
However, while great inroads are being made in this area by improving insulation, switching to renewable energy sources and reducing reliance on gas for hot water and heating, focusing exclusively on reducing operational emissions misses the crucial role of embodied carbon.
Embodied carbon is defined by the UK Green Building Council as ‘the total greenhouse gas emissions generated to produce a built asset’. This means taking into consideration the amount of carbon dioxide (CO2) emitted from extraction, processing and manufacturing, transportation and assembly of every building component and product used.
This key element of reducing carbon emissions within the built environment was missing from the Future Homes Standard, released at the start of 2021. Backing the need to pay closer attention to embodied carbon is Architects Climate Action network (ACAN). In February, ACAN launched its ‘Regulate Embodied Carbon’ campaign including a report on the case for decarbonising construction.
Among the achievable recommendations set out by ACAN’s campaign, one of the simplest ways to capture carbon and reduce CO2 in the atmosphere is by increasing the use of wood in construction. The Climate Change Committee has previously recommended increasing the use of wood in construction and developing policies to minimise the whole life carbon impact of new buildings.
Low carbon heating and energy systems are imperative, but they are only part of the solution to reduce harmful CO2 emissions generated by buildings. By taking a fabric first approach and choosing a natural and renewable material such as timber, embodied carbon is also reduced.
Timber structural systems, such as timber frame or cross-laminated timber, not only embody carbon but also deliver the benefits of modern methods of construction. Choosing build systems like these can reduce build time, reduce waste, improve safety and cause less disruption in the local area.
While we regularly hear that building with timber is good for the environment, this is often contradicted by negative messages about deforestation or poor forestry practices.
However, there is a vast difference between sustainably managed forests that are planted and harvested in a carefully planned way – and badly planned or unauthorized deforestation carried out for short-term profit.
Forestry is a specialist industry with a long-term view, taking into account the time it takes to plant, grow and manage trees, forests and woodlands. Different species grow at different rates and are harvested accordingly. Young trees absorb and store much more carbon than their older counterparts as they are growing, so the practice of sustainably harvesting older trees for building materials is both good forestry management as well as beneficial for the environment.
Moreover, carefully managed woodlands encourage valuable biodiversity, providing homes for all manner of wildlife and ecosystems from fungi and beetles through to small mammals, birdlife and larger predators.
Well managed forests and woodlands also provide much-needed space for human recreation, boosting wellbeing by providing wooded walks, cycle routes and bridleways. For more information about the benefits for sustainable forestry, read our feature.
Firstly, as they grow, trees absorb carbon dioxide which is stored in their trunks and branches. Known as sequestered carbon, this CO2 stays stored within the timber even when the trees are felled and used for building materials, hence the carbon is ‘locked in’.
Secondly, timber is a naturally renewable material and using it in a managed way will not deplete the world’s finite resources.
Thirdly, choosing to build with timber where appropriate in place of more ‘energy-hungry’ materials such as concrete and steel can reduce the amount of embodied carbon associated with that building.
Take a look at our infographic which explains the difference between embodied, operational and sequestered carbon.
Despite the fact that timber is a naturally occurring and sustainable material, its supply is not without limits.
The UK currently imports 80% of its timber from overseas which means that it must be transported by train, boat and lorry to its destination. According to Forest Research, the UK is the largest net importer of wood and wood products after China.
Boosting the supply of home-grown timber is therefore considered another important element of our route to net zero. In the UK, Scotland and Wales are leading the way in this area with 19% and 15% of their land given over to forestry respectively. England lags behind with just 13% of its land given to forestry. The UK Committee on Climate Change report ‘Land use: Policies for a Net Zero UK’, recommends increasing this by 4%, hence the government’s target of 30,000 hectares of tree planting per year.
Other key factors in improving sustainability are reducing the amount of raw materials we use, re-using materials where possible, recycling and reducing overall wastage.
It’s essential that we think more carefully about how we use our resources and what we do with them at the end of their life. Designing buildings that can be flexible during their lifetime, and also designing in the option to dismantle and re-use building components and materials is an increasingly important element of sustainable architecture and design.
6 Orsman Road by Waugh Thistleton is an office building constructed from CLT and designed to be dismantled at the end of its life. It was also designed to be fully flexible, so as tenants’ needs change over time, the building can be reconfigured accordingly. Similarly, created by Lifschutz Davidson Sandiland, the Paradise Gardens homes were designed to be easily reconfigurable to adapt to the changing needs of residents over time.
The Paradise building for Bywater Properties aims to be an exemplar in net zero architecture. Flexibility for the future was a key part of the brief and the building is designed to be re-configurable internally and also to be demountable at the end of its life.
When specifying timber, always opt for timber that is FSC or PEFC certified. These stamps of approval show that the timber has been sustainably forested and managed.
Choosing the right species of wood for the application and considering where it was sourced is also important. Think carefully about the species of timber you’re using and where it has come from. The TRADA Wood Species Database has more details.
For guidance on specifying the timber with the lightest touch on the environment for your project, take a look at our lifecycle database.
Environmental Product Declarations aim to provide all the information required to enable specifiers to make informed choices about the environmental impact of individual options, and to compare like with like. For more information about EPDs and the differences between them, take a look here.