Concrete Pipes

Adopting Concrete Drainage Reduces Whole Life Carbon

BPDA has published the results of a comparison study into the whole life carbon impact of concrete and equivalent plastic pipes, highlighting that concrete is the low carbon choice.

This year UK Concrete, the group representing the UK concrete industry will develop and adopt a new carbon roadmap to deliver a ‘net negative’ industry by 2050. The announcement means that the concrete industry is not only committing to meet the UK target of ‘Net Zero’ by 2050 but is also committing to removing more carbon from the atmosphere than the industry emits each year.

The concrete and cement industry has a strong track record, having already delivered a 53% reduction in absolute carbon emissions since 1990 and is decarbonising, as a whole, faster than the UK economy. At a British Precast level, since the launch of the Sustainability Strategy in 2007, manufacturing carbon emissions for the sector dropped by 43%.

One of the many steps on a roadmap to a future low carbon economy is selecting the right materials to build much needed infrastructure. The British Precast Drainage Association (BPDA) is publishing the results of a comparison study into the whole life carbon impact of concrete and equivalent plastic pipes, to highlight that concrete is the low carbon choice. The study draws on a sensitivity analysis carried out by external consultancy Circular Ecology, which allowed British Precast to model the impact of both concrete and plastic pipeline systems.

The findings show that at the majority of pipe diameters, when plastic pipe ring stiffness and resin sources are evaluated, installed concrete pipes have lower embodied carbon (measured in GWP = Global Warming Potential) than plastic alternatives. For large diameter pipes the difference is the most marked with the GWP impact as much as 47% higher than that of a concrete equivalent (assuming equal service lives).

When the full pipeline lifecycle in taken into consideration the BPDA believe that the GWP impact of a plastic pipeline could be more than double the impact of a concrete pipe due to concrete’s longer service life.

The RICS (Royal Institute of Chartered Surveyors) has long believed that it is crucial that specifiers make decisions based on the whole life carbon of construction products, rather than cradle to gate or partial studies which are essentially the ‘tip of the iceberg’. Looking at the full picture on emissions is a key theme of the document.

The BPDA adopted a ‘whole life’ principle similar to that advocated in PAS2080 right at the start of the project. Data in the study is based, where possible, on Environmental Product Declarations, like the BPDA DN600 example published in 2017. The study covers not just the creation and transportation of the pipe itself, but also the excavation and transportation of the required bedding material. Further considerations include the demonstrable 120+ years’ service life of concrete pipes compared to just 50+ years for many plastic pipes, a variable which is vital if projections of an 800-year service life requirement for UK water assets bare out. End-of-life scenarios are also considered including the potential need to incinerate the plastic pipe waste at the pipeline decommissioning stage, while concrete pipes can be dug up and reused elsewhere or broken up and recycled, allowing for carbonation to take place removing CO2 from the atmosphere.

When all these facets across the full life of the products are considered, the difference in global warming potential impact is stark. The graph below shows the relative impacts of comparable DN2100 pipes where resin is imported from outside the EU – here concrete pipelines have less than half the carbon impact of plastic pipes.

As a specifier, your choice of precast concrete pipes provides the opportunity to save carbon across the whole life of a pipeline. Lower carbon through design, significant extension of the working life and concrete carbonation at the end of life.

For more information on why precast concrete is the low carbon option download the summary results here

Published on 1st September 2020

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