Nick Turner, Head of Surveying, Woodgate & Clark takes a look at low carbon strategies and compliance across the rebuild and new build sector.
The UK has a legally binding target to reach net zero by 2050i and at COP26 the Government committed to achieving 68% reductions in carbon emissions by 2030. Considering the UK built environment is responsible for approximately 25% of total UK greenhouse gas emissions it is perhaps surprising that the embodied carbon cost of construction is not required by current policy to be assessed or controlled, other than on a voluntary basis.
Embodied carbon is the total carbon emissions of all building materials and products and the construction involved to put them together. It accounts for about 20% of the carbon emissions from the building sector.
Lack of policy has meant lack of progress in reducing emissions within the built environment and low-carbon building products cannot meet current demand. Low-carbon building materials are materials with both low embodied energy and carbon in their production, assembly, and transportation processes.
Compounding this problem, there are insufficient incentives to develop and use these materials.
For example, obstacles remain in timber products that prevent their take up in construction, including, Issues regarding fire risk and insurance; price volatility; securing sustainable and local supply chains; and the skills gaps in the use of timber.
It would make sense for whole-life carbon assessments for buildings to be set within building regulations and the planning system. This could provide a measure for progressive carbon targets for buildings, to match the pathway to net zero.
This approach could incentivise:
· More retrofitting
· The development and use of low-carbon materials
· Investment in low-carbon construction skills.
A huge number of materials and products used in building, such as concrete, steel and aluminium, are created by a production process of raw material extraction, raw material process, melting, manufacture to final products, and transportation to building sites. Each of the steps consumes energy, which is also expressed in terms of carbon emissions.
So what are the alternatives?
Carbon sink materials are mainly sourced from harvested wood products (HWPs). Wood is harvested from trees that capture carbon through the process of photosynthesis. In fact, fifty per cent of the dry weight of wood is carbon, and the amount of carbon in 1m³ of wood is similar to that in about 350 litres of petrol.
Low-carbon building materials should also be used as much as possible but these products are interpreted differently in different contexts. For example, metal products are considered to be high-embodied carbon materials because the extraction and refinement processes involved are carbon intensive. However, recycled metal products used in new buildings can be considered low-carbon.
The building material with the lowest carbon footprint is widely considered to be Rammed Earth. This is basically an old technique that uses only natural raw materials such as earth, chalk, lime or gravel. The next most environmentally friendly material is softwood timber. Softwood is often used to frame modular building sections due to its light weight and sustainability. Softwood has an average of 110kg of embodied carbon per m³.
However, recognising that Timber related industries in the UK are responsible for around 1.5M tonnes of CO2 and around 3.6M tonnes of CO2e from processing and transporting timber from overseas, key UK industry timber trade associations have launched the Timber Industry Net Zero Roadmap to tackle this. Given that 49% of emissions are related to transport, efficiencies in transportation could have a significant impact, as will specifying ‘locally sourced’ timber.
Laminated timber is the next best eco-friendly material and is making a return to UK construction as it offers huge design flexibility and is very light while being very strong. It is effective acoustically and thermally and generates virtually no waste on site.
Then we have stone. All stone requires is quarrying and shaping. It is fully natural, durable and has been used for thousands of years.
To provide some perspective, the average embodied carbon of laminated timber is 219kg per m³, stone emits around 237kg per m³, of embodied carbon, whereas reinforced concrete emits 635kg embodied carbon per m³, glass 3600kg per m³, steel 12090kg per m³, and aluminium 18009kg per m³.
The insurance industry is already playing a role in helping to achieve the U.K’s net zero targetsii. At the same time, the market is facing rising claims costs – in part due to our changing climate. The first priority for Woodgate and Clark is managing these costs for our insurer clients and ensuring there is no ‘betterment’, in line with policy terms, when it comes to agreeing the repair specification. However, it is clear that if policy wordings allowed, opting for lower carbon materials, where feasible, could have a longer-term benefit in reducing emissions. Clearly this would need to be factored into the economics of the cost of insurance and that’s part of a much bigger discussion for the industry as a whole.
Read Woodgate and Clark’s series of articles on Low Carbon materials at: https://www.woodgate-clark.co.uk/media