Sustainability: Explained

In the midst of the global climate emergency, we know that it is essential that coordinated cross-industry action is taken to decarbonise our built environment. To build the homes, offices, schools and hospitals that we need, we must reevaluate our consumption of resources, limit greenhouse gas emissions and adopt circular economy principles.

This page addresses the role that timber can play in meeting our climate emergency commitments and creating a more sustainable world. It will direct you to further resources on all topics, providing you with information to enable you to source and use timber sustainably and well.

What is sustainability?

Sustainability means using resources in a way that fulfils the needs of the present without comprising the ability of future generations to meet their own needs.

It is based on the ecological principle that our future depends on the health of our natural environment. Sustainable practices avoid the depletion of natural resources and support ongoing environmental, social and economic well-being.

To do this, sustainable practices should:

• Minimise negative environmental impacts and eliminate carbon emissions
• Efficiently use resources, prioritising renewable resources over finite ones
• Embrace circularity to extend the life cycle of products and minimise waste
• Support social equity, economic viability, and biodiversity.

Is timber sustainable?

When sourced from responsibly managed forests, timber is a naturally renewable, sustainable building material which:

1. Sequesters carbon as trees grow.
2. Stores carbon in harvested wood products.
3. Substitutes for carbon intensive materials such as steel, concrete and plastics.
4. Drives Sustainable forest
5. Contributes to a Circular economy, as wood products can be reused, recycled and recovered for low-carbon energy at end-of-life.

To be sustainable, timber must be grown and harvested in responsibly managed forests, which are continually replenished and regenerated. Balancing the needs of wildlife, environment and local community, sustainably managed forests provide numerous benefits from carbon capture and flood risk mitigation to the preservation of biodiversity and provision of local livelihoods.

Sustainable timber practices include selective harvesting, reforestation, habitat restoration, and establishing protected areas. In a sustainable forestry model, at least two new trees are planted for every tree harvested, but this number can be much greater. These practices help to ensure the long-term health of our forests and, crucially, preserve their ability to act as carbon sinks.

Certification standards, such as FSC, or PEFC, and Grown in Britain certified wood, confirms that the timber is sourced from responsibly managed forests via Chain of Custody throughout the full timber supply chain. Another type of certification is FLEGT (Forest Law Enforcement, Governance, and Trade) licences, which confirm that timber originates from a producer country that has entered into and successfully executed a legally binding Voluntary Partnership Agreement (VPA) with the EU and/or UK to supply responsibly sourced timber.

Timber Development UK members must also agree to comply with our Code of Conduct. This includes a mandatory annual audit for members importing timber into the UK to comply with the UK Timber Regulation (UKTR).

Learn more about sourcing sustainable timber and UK certification

Global Forests Need Global Governance: How can we help stop illegal deforestation?

Timber and climate change

Trees sequester (absorb) carbon dioxide (CO2) as they grow, helping to reduce the concentration of carbon dioxide in the atmosphere.

This is then stored in the form of biogenic carbon in the diverse timber products that are derived from sustainably managed forests and kept locked away in our built environment.

By substituting carbon intensive materials such as steel or concrete for timber, which has a uniquely low impact production cycle, the use of timber as a structural (or non-structural) material helps to reduce the whole life carbon footprint of construction projects.

However, if forests are cleared for timber extraction and not replenished the Earth’s capacity to sequester carbon is reduced. When cut trees are burned or left to decay, their stored carbon is released back into the atmosphere.

By increasing the growth of sustainably managed, productive forests; reducing the carbon emissions associated with construction; and keeping carbon stored in the built environment for as long as possible, the increased use of timber can play a crucial role in mitigating climate change.

The climate case for wood

The construction and built environment sector is responsible for approximately 40% of global carbon emissions.

This comes from two main sources:

1. The energy we consume within buildings for heating, cooling and lighting (operational emissions).
2. The emissions associated with the extraction, processing and manufacture of building products, and the incorporation of these products into the final building, their use and end-of-life impacts (embodied emissions).

Increasing the use of wood is an effective way of reducing both.

Wood is one of the only sustainable construction materials, which grows worldwide, that can enable a substantial decarbonisation of the built environment based on existing business models and proven technology; providing vast carbon sinks in our rural areas and carbon stores in our cities.

Timber has naturally insulating properties, reducing operational emissions created due to heat loss within buildings. Along with its natural breathability properties, this makes timber and timber products ideal for retrofitting and improving the energy performance of millions of existing homes and other buildings. It is also highly suitable in supporting energy efficient new build construction, such as Passivhaus.

Lifecycle Assessment studies consistently show that net emissions from buildings constructed largely from timber are lower than equivalent steel or concrete structures, as well as acting as a carbon store. Using more wood in the built environment, including in furniture and interiors, is a natural, cost-effective, and sustainable carbon-capture solution. In addition, using wood products in construction displaces the use of carbon intensive alternatives such as steel, concrete and plastics, thus avoiding further emissions.

• Timber in Construction: Barriers and Solutions: This report looks to assist the Government’s work, outlining how we can safely and effectively expand low-carbon timber construction in the UK.
• Wood – Building the Bioeconomy: Throughout this resource some of the following topics will be explored – Dawn of the wood age | Climate, carbon and wood | Wood at the root of a bioeconomy
• Global Forests Need Global Governance: This paper, the Tropical Timber Accord, is a global call to action from the international forests and timber industry to COP26 to strengthen legal governance of forests and forest supply chains.
• Growing Our Low-Carbon Future – Time For Timber: This policy paper, prepared for COP26, sets out the case for how we can make greater use of wood to transform our built environment, which currently is responsible for approximately 40% of global energy related CO2 emissions.

A low carbon material

Using more wood in the form of timber products can actively contribute to reducing our carbon emissions: facilitating environmentally friendly construction and encouraging growth in sustainably managed forests.

This is because:

• Trees capture CO₂ from the atmosphere and store it as carbon: each 1m³ of wood grown by a tree stores around 0.75 tonnes of sequestered CO₂.
• Mature trees are harvested when their ability to sequester carbon starts to reduce, and their sequestered carbon is stored in buildings and other wood products, which stores the carbon for their entire life.
• Using timber helps reduce carbon emissions, both through the use of a low embodied carbon timber product and substitution of other high carbon products.
• Timber systems can be designed to extend their life as well as the products being modified or protected with additional treatments. They can also be repaired, reused and recycled numerous times before they reach the end of their life.
• We can keep planting more trees to replace those used for harvested wood products – and every tree planted captures more CO_2.

The role of timber in delivering net zero

For the UK to meet its legal target of Net Zero Carbon emissions by 2050, the construction industry needs to embrace the concept of Net Zero Whole Life Carbon.

A net zero whole life carbon asset is one in which the sum total of all asset-related greenhouse gas emissions – both operational and embodied, over its whole lifecycle – equals zero.

The UK Committee on Climate Change estimates that, based on the current rates of use of timber frame in UK housing (15-28%), one million tonnes of carbon is stored in UK housing each year (Committee on Climate Change, 2018). This is based on research by the Biocomposites Centre at Bangor University (Spear et al., 2019), which estimate that a typical masonry 4-bed detached house will store 8.5 tonnes of CO₂; whereas using timber frame will increase this to 12.7 tonnes of CO₂, and a 4-bed detached house using both timber frame and cladding could store nearly 15 tonnes of CO₂.

The following resources explain where timber fits within the cycle, and how and when the carbon emissions and carbon sequestration associated with timber should be taken into account, when calculating the Whole Life Carbon emissions of assets.

Net Zero Roadmap – how the timber industry can address the climate crisis and build a net zero future

Net Zero Action Plan Tracker for the timber industry

Assessing the carbon related impacts of timber in construction paper

Timber and the circular economy

The circular economy aims to keep resources in use at as a high value as possible, as long as possible –recovering and regenerating products at the end of each service life.

Timber has the ability to contribute significantly to the circular economy as:

• It is a renewable resource that is comparatively low energy to produce – growing naturally with sunlight and rain water
• It produces no waste that cannot be recycled or used as biomass to generate energy
• Timber products can be repaired, recycled and repurposed for various applications. For example, a timber pallet could be repaired numerous times before it is turned into wood chips to create a chipboard panel
• Reclaimed timber can be salvaged and reused in new construction
• Timber’s light weight and superior thermal properties make it ideal for retrofit, reuse and extension, allowing us to update and retain our existing building stock

It is important that circular principles are fully incorporated into timber production and use, ensuring that we use timber sustainably and responsibly. This involves considering the entire lifecycle of timber products, from sourcing and manufacturing to design, use and end-of-life treatment, to make most efficient use of this valuable resource at every stage.