There is widespread agreement that we need to reduce carbon
emissions. Where there tends to be disagreement, is how construction
needs to change to achieve this. Progress requires new tools and a
shared language, says Timber Development UK Sustainability Director
Charlie Law.
The construction and built environment sector
are responsible for nearly 40% of global carbon emissions, of which a
significant percentage comes from the extraction, processing and energy
intensive manufacturing of building products – known as embodied carbon.
After many years of efforts across the industry, embodied carbon as an
issue is finally emerging into the mainstream. We see this in the debate
of how we should handle our existing buildings, with the carbon cost of
the proposed demolition of M&S on London's Oxford Street grabbing
national headlines, in local planning policy, with the London Plan
including a requirement for wholelife carbon assessments, and in the
Houses of Parliament where the 'Part Z' for embodied carbon recently
came forward.
While excellent progress is being made, there
remain outstanding challenges. For the timber industry this is seen in
the debate on how to measure the impact of carbon sequestered by wood
products. With the many differing opinions, it has sometimes been
difficult to fully communicate the benefits which timber and timber
building systems bring to reducing embodied carbon.
Measuring the benefits of timber and carbon
In
our new technical paper 'Assessing the carbon-related impacts and
benefits of timber in construction products and buildings' we set out to
solve this problem by communicating a clear process for accounting for
carbon in timber buildings and Environmental Product Declarations (EPDs)
in accordance with the latest European Standards (EN 15978 and EN
15804+A2) and RICS Professional Statement on Whole Life Carbon
Assessment in the built environment.
This is important. As with
any other core part of a business, from finance to operations, 'if you
can't measure, it you can't improve it'. By setting out a clear process
for counting carbon within wood products, using the latest industry
standards, we are helping ensure that:
• Building designers,
clients, and contractors can better understand and assess the embodied
carbon associated with buildings and other structures
• Product manufacturers and suppliers can demonstrate the carbon impact of their wood products.
To
ensure the rigorous application of these standards to an industry
leading level we worked with an independent party, Jane Anderson of
ConstructionLCA, a world-renowned expert on embodied carbon, lifecycle
assessments and EPDs for many different materials within the
construction sector, to develop this technical paper.
Solving the biogenic sequestered carbon puzzle
To
fully understand the carbon impact of construction requires a whole
life carbon assessment. Within this assessment it has not always been
simple to quantify what the impact of the biogenic carbon, which is
sequestered by timber, is on the overall carbon footprint of a
construction project.
Biogenic carbon is shown within the whole
life carbon model only as it enters the system, when the timber is
harvested within Module A1 (extraction), and when it exits the system
(through transfer to another product or emission to atmosphere) within
Module C3 or C4.
This means there needs to be a clear
understanding of the construction product all the way from the forest –
where our paper starts by looking at the forest ecosystem as a carbon
sink – through to its end of life when it might be recycled into another
product, converted into bioenergy, or otherwise released into the
atmosphere, as well as all points in between.
Where timber is
sourced from a sustainably managed forest then the sequestered biogenic
carbon stored within the product can be considered as part of an
assessment. On average, a balance of 568 million tonnes of CO2 has been
added to the forestry carbon sink in Europe annually over the last ten
years. The amount of carbon stored in harvested wood products, including
timber used for building, is estimated to increase by 40 million tonnes
of CO2 each year.
The carbon sequestered from the products
biogenic origin then should be listed within the EPD of a product and
inform the whole life carbon assessment of a building. Where only an
upfront carbon assessment is carried out (Modules A1-A5 only) then the
sequestered carbon cannot be included in the calculation but can be
stated as a separate 'stored carbon' figure.
Another key area where this paper provided a much-needed update is on the end-of-life (EoL) scenarios for timber products.
Previously
the RICS Professional Statement provided an EoL scenario for all timber
whereby 75% was directed to energy recovery and a quarter to landfill.
This was incorrect. By taking Defra estimates of the amount of timber
waste production, and Environment Agency landfill data, it was
calculated that less than 1% of waste timber is ending up in landfill.
Based
on this data, and data from the Wood Recyclers Association on the EoL
routes for timber, this paper sets forth more likely EoL scenarios for
solid hardwood and softwoods, engineered timbers, wood panel products,
and preservative treated and coated timber, with information on the
potential for reuse in their original form, and percentages for
recycling and energy recovery.
Creating a net zero future for the timber industry
By bringing these two associations together as one we are creating the largest, most comprehensive supply chain body in the UK, spanning from sawmill to specifier and all points in between. We want to use this new organisation to capitalise on the growing interest in designing with timber and to act as an agent of change towards more sustainable, low carbon forms of construction.
This paper will be the first of many as we set out to use our central position in the timber industry to build a roadmap, along with the tools, training, guidance, and auditing to support the sustainable timber supply chain to become a net zero carbon industry.
