Using the Timber in Construction Roadmap to Reduce Embodied Carbon in the Built Environment

In this blog, BWF Technical Director Kevin Underwood outlines how the Timber in Construction (TiC) roadmap aims to reduce embodied carbon in construction. Kevin discusses the (Conservative) Government commitments to increase timber use, the roadmap’s seven priority themes, and the importance of accurate carbon impact data. The article highlights the need for industry collaboration to ensure sustainable timber practices and drive innovation in timber construction.

The Conservative Government recognised the need to make good use of the materials that woodland in England provides and committed in the 2021 Net Zero Strategy, the 2021 England Trees Action Plan and the 2023 Environmental Improvement Plan, to increase the safe use of timber in construction (TiC).

These commitments will help reduce embodied carbon in the built environment and drive investment into tree planting, forest management and domestic supply chains while ensuring that any increase in the use of timber is sustainable and does not contribute to greater rates of global forest degradation or deforestation. It is anticipated that the current Government will continue with these policies.

The Timber in Construction roadmap outlined the opportunities and barriers to the use of timber in construction in England, centred around seven priority themes:

1: improving data on timber and whole life carbon

2: promoting the safe, sustainable use of timber as a construction material

3: increasing skills, capacity, and competency across the supply chain

4: increasing the sustainable supply of timber

5: addressing fire safety and durability concerns to safely expand the use of engineered mass timber

6: increasing collaboration with insurers, lenders, and warranty providers

7: promoting innovation and high performing timber construction systems

Under priority theme 1, improving data on timber and whole life carbon, it is recognised that efforts to reduce the embodied carbon emissions of new builds are a key driver for the increased use of timber in construction in England. In the Net Zero Strategy, the Conservative Government committed to help the construction sector improve reporting on embodied carbon in buildings and committed to exploring the potential of maximum embodied carbon levels in new buildings in the future.

Approach to measurement is central to this and standards for whole life carbon assessment methodology (BS EN 15978:2011), and for producing Environmental Product declarations (BS EN 15804:2012+A2:2019) already exist.

BS EN 15978:2011, Sustainability of construction works. Assessment of environmental performance of buildings. Calculation method.

The BSI Knowledge website states, “This European Standard specifies the calculation method, based on Life Cycle Assessment (LCA) and other quantified environmental information, to assess the environmental performance of a building, and gives the means for the reporting and communication of the outcome of the assessment.“

Note: BS EN 15987 is under review and the revised draft has recently been through its CEN Enquiry or public commenting stage.

BS EN 15804:2012+A2:2019, Sustainability of construction works. Environmental product declarations. Core rules for the product category of construction products.

The BSI Knowledge website states, “This European standard provides core product category rules (PCR) for Type III environmental declarations for any construction product and construction service.”

We need to ensure that the carbon impact data for not only timber, but all construction materials, is robust and used consistently. For timber specifically, this includes ensuring that environmental product declaration data is comprehensive and consistent; understanding the impact of timber construction on a building’s lifespan and subsequent impact on demolition or construction rates and associated carbon emissions; and understanding the impact of timber construction on transport emissions.

The treatment of timber products at the end of a building’s life can also have a significant effect on the overall carbon impact. According to Timber Development UK (TDUK) less than 1% of UK timber and wood products go to landfill, which is a significant achievement. However, industry and government need to work together to further increase the opportunities for re-use and recycling of timber, such as promoting new approaches to design. (see RISE Research Institutes of Sweden report, Design of Timber Buildings for Deconstruction and Reuse – Three methods and five case studies, April 2022).

Under the TiC Roadmap, the Conservative Government committed to:

• seek input from industry on its approach to measuring and reducing embodied carbon in new buildings.

• explore the potential of embodied carbon limits for buildings in the future.
• explore ways of deploying a broad carbon assessment, and how they may be used in a plan-making context or as a tool for assessing individual developments.
• work with industry, and academia, to expand and improve the evidence base for timber and embodied carbon.
• work with industry to explore options to reduce carbon emissions associated with timber construction at “end of life” and encourage greater circularity in the supply chain.

Industry will:

• continue voluntary work to measure and reduce embodied carbon.
• encourage the inclusion of data, on projects that use timber, in the Built Environment Carbon Database once it launches in 2024, to enable improved benchmarking and information sharing on the carbon performance of timber construction projects.
• improve the quality of timber environmental product declarations (EPDs) including through creation of a new, free to use timber EPD database.