Timber: A supporting role for sustainability

Andrew Orriss from the Time for Timber campaign discusses how widespread use of timber in construction could prove to be the real ‘net zero hero’.

With estimates suggesting that the construction industry contributes an eye-watering 35% of global carbon emissions, it’s clear that something needs to change in the way we construct new buildings – particularly when it comes to volume housing. Yet, despite UK government targets of achieving net zero carbon by 2050, large-scale adoption of sustainable building materials such as timber is frustratingly slow.

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In the wake of the COVID-19 pandemic, the housing crisis is once again in the spotlight – with the UK lagging behind housing demand in terms of both supply and quality. Most notably, the lockdowns of 2020 have highlighted the urgent need to improve the availability of social housing – particularly for the millions of families living in substandard private rented homes or temporary accommodation. Certainly, the sector must follow the prime minister’s direction to “Build, build, build”, but priority must be given to delivering genuinely affordable social homes – and this must be achieved at pace, while also keeping environmental obligations in mind.

Widespread use of structural timber would make this lofty goal more attainable. For one, the material is particularly suited to modern methods of construction, such as offsite and modular design, as it is clean and easy to process within factories. What’s more, the timber industry has robust and mature supply chains, meaning a steady flow of materials can be ensured. These innovative approaches to long-standing construction challenges are enabling the rapid delivery of homes, particularly for social housing providers and local authorities.

In addition to these benefits, structural timber has a key role to play in reducing the overall carbon emissions of the construction industry, thanks to the carbon storage potential of timber harvest crops. By comparison, a report published by Chatham House (Making Concrete Change: June 2018) shows that cement is the source of 4-8% of total global carbon dioxide emissions. In fact, when used instead of other building materials, a single cubic metre of timber will save around 0.8 tonnes of carbon dioxide emissions.

Timber is carbon negative from the cradle to the grave, storing more carbon than it emits during processing and installation. As the only truly renewable building material, it’s easy to see why so many organisations are embracing timber as the new standard. Indeed, as far back as 2012, the borough of Hackney in East London was forging ahead by adopting a planning policy that favours wood, where feasible, as the primary construction material. Similarly, the French government recently announced new sustainability legislation to help make the country carbon-neutral by 2050. The new law, which becomes enforceable in 2022, will mandate that all new public buildings in France are built from at least 50% timber, or other natural materials.

In the UK, the government has committed to introduce a Future Homes Standard in 2025, as part of its journey towards meeting the net zero target. It is estimated that currently, new and existing homes account for around 20% of emissions. Homes built to the new standard will be required to achieve 75-80% less carbon emissions than those built under the current Approved Document Part L 2013 of the Building Regulations. It is also expected that approaching revisions to the Building Regulations for England and Wales and Section 6 of the Scottish Building Standards will have a meaningful uplift towards the Future Homes Standard. The intent is to make new homes more energy efficient and to future proof them in readiness for low carbon heating systems.

With this increasing focus on efficiency of the fabric of the building, the use of timber frame and structural insulated panel construction can offer a good deal of external wall flexibility when the demands for high thermal insulation are required. In simple terms, it is easier to fill the building envelope with insulation in a structural timber internal leaf, than filling a cavity between two traditional masonry wall skins.

As the Ministry for Housing, Communities and Local Government (MHCLG), drive the regulatory requirement for buildings to use less and less energy to heat and cool as part of the carbon reduction of buildings in use, it can be expected that structural timber systems will be identified as a key material in achieving this goal.

Despite all this, efforts to expand the use of timber within the UK have been held back to some extent by misconceptions regarding its suitability for certain construction purposes. Most notably, there remains a long-held, incorrect assumption about the fire risk of structural timber - meaning some social housing providers and local authorities may be put off using the material. While this approach is well-intentioned, it’s undoubtedly doing more harm than good, with some local authorities missing out on the benefits that this versatile material can offer.

As well as offering a more sustainable construction option, timber is helping organisations to build quality homes faster. As such, not only does the material represent an obvious, sustainable and environmentally positive solution, which can help to drive down total carbon emissions, but an avenue to accelerate housing delivery at a time of considerable strife.

Andrew Orriss is STA Assure Director, Structural Timber Association.

www.timefortimber.org

References:

Hurmekoski, E. 2017. How can wood construction reduce environmental degradation? European Forest Institute

https://www.conservativehome.com/platform/2020/07/danny-kruger-we-should-build-build-build-the-social-housing-we-need-and-build-it-beautiful.html

https://www.building.co.uk/news/hackney-moots-timber-first-planning-policy/5036737.article