EN 15804, the construction product EPD standard, attributes the impact of treating waste to the waste producer, according to the polluter pays principle. After treatment, when waste has been recovered and reaches the “end of waste”, the resulting secondary material enters its next product system with no impact. Those using secondary materials therefore get a benefit as their input material has no impact, whilst primary input materials will have impacts from extraction and processing.
Anyone using secondary material needs to take account of any manufacturing impacts after the “end of waste” to make their products – these are the impacts reported in Modules A1-A3 of an EPD. At the end of life of the construction product, the impact of waste processing until the end of waste state is reached is reported in C1-C3, the impacts of disposal (landfill or incineration) if the waste cannot be recovered are reported in C4.
This approach used in EN 15804 is sometimes known as the recycled content, cut-off or 100:0 approach in life cycle assessment.
Where end of life waste is recovered and used in the next product system, EPD to EN 15804 are able to show the benefits of this recovery as additional information in Module D, but Module D is outside the system boundary of the product system. The approach in Module D shows the “avoided burdens” from recycling, and derives from the recyclability, avoided burdens or 0:100 approach sometimes used in LCA, which the metals industry often recommends.
Perhaps the most important question is why does EN 15804 use the 100:0 recycled content approach that attributes the benefit of recycling to the user of recycled content, whilst only providing additional information on the benefits of end of life recycling in Module D, rather than within the product system LCA. The answer, in my view, lies in looking at the construction sector as a whole.
In the UK, a mass balance for the construction industry conducted in 2000 calculated the total mass of materials added to the built environment in 1998 to be 275 million tonnes, which required an input of 420 million tonnes of material resources, of which 43 million tonnes were recycled material, giving a recycled content of around 10% (Viridis, 2003) with an overall resource efficiency of only 65%. At this point in time, just over 50% of construction and demolition waste was estimated to be recycled.
In contrast, DEFRA estimate the most recent recovery rate in 2014 from non-hazardous construction and demolition waste in the UK was 89.9 per cent, with over 49 million tonnes of waste recovered. (DEFRA, 2016). The total amount of waste recovered or recycled in the UK in 2014 was only 91 million tonnes, accounting for less than 50% of all UK waste generated, and if ALL of this recovered waste was used in construction, it would still give a recycled content of less than 50%.
Within UK construction, we are therefore already achieving very high levels of end of life recycling, but are still using lower percentages of recycled content with low overall resource efficiency.
With an 89% recycling rate, most UK construction products would already be able to show considerable benefits from end of life recycling if EN 15804 was changed to give end of life recycling the benefit using the 0:100 approach. This approach would also give those using recycled content higher impacts, and over the full life cycle taking account of the avoided burdens, primary and recycled products would have similar impacts, meaning there would be less reason to recycle.
Instead, the incentive to recycle is, in my view, correctly placed with the user of recycled content in EN 15804, following the polluter pays principle. The use of the 100:0 recycled content approach in EN 15804 recognises the need to incentivise construction products to use secondary materials and to look not just to construction but to other sectors with much lower waste recovery rates to source secondary material.
Viridis, 2003 https://trl.co.uk/reports/VR4%20%28REVISED%29
DEFRA, 2016: https://www.mrw.co.uk/download?ac=3050506