Engineering Net Zero on the Bridgwater Tidal Barrier

MARKETS: Water

LOCATION: Bridgwater, Somerset, UK

CLIENT: The Environment Agency and Somerset Council

COMPLETION DATE: Forecast 2029

Using our custom BIM Analytics – Carbon tool to reduce the impact of carbon-critical design elements by 70% and halve the embodied carbon of the new Bridgwater Tidal Barrier

Infrastructure accounts for over half of the UK’s carbon emissions. A great deal of this carbon is generated across the construction process and supply chain, with each ton of concrete, for example, producing about 73.1kg of CO2. We measure this impact through embodied carbon, or the total greenhouse gas emissions associated with the extraction, manufacturing, transportation, and assembly of building materials, as well as the construction process itself.

Unfortunately, calculating the embodied carbon of a new piece of infrastructure is typically a complicated and time-consuming process. As a result, this is generally only done at the end of the design stage, once all the decisions have already been made. This limits the ability of the design team to make informed choices about their environmental impact, and often results in costly redesigns later in the process. However, by combining carbon calculation tools with our tailored digital design workflows, the AtkinsRéalis team have designed a powerful solution…

A digital design solution for the Bridgwater Tidal Barrier

AtkinsRéalis were commissioned by the Environment Agency (EA) to undertake the detailed design for a tidal barrier to protect the town of Bridgwater from tidal surge flooding until 2125. This commission included not just the tidal barrier structure itself, but also the operational buildings and site, approximately 9 kilometers of raised downstream defenses, and modifications to 12 existing structures upstream of the barrier to improve fish and eel passage. The team were set a target of a 45% reduction in whole-life carbon from the baseline, in line with the EA’s sustainability targets.

To ensure that we could meet this target, the team deployed our new BIM Analytics – Carbon package, a design workflow that AtkinsRéalis has been developing to measure the embodied carbon of the whole design in real-time, as it’s designed. This allows our teams to understand the impact of their design choices as they make them and to iterate and experiment with lower-impact alternatives. At the EA’s request, this tool was integrated with their existing carbon tool, ERiC, to ensure our results would comply with their accuracy and data standards.

The team used Building Information Modelling (BIM) software to create their first detailed design of the tidal barrier, before running our BIM Analytics – Carbon software. This rapidly assessed the embodied carbon of the entire design, as well as each individual element, to provide a detailed carbon breakdown. The software then displayed this information visually through a custom PowerBI dashboard – breaking the detailed design down by construction materials and components and creating a 3D heatmap to reveal carbon-critical design elements.

From this, the team easily identified the proposed steel-cased reinforced concrete piles as contributing more than 25% of the design’s total embodied carbon and began looking at ways to reduce the element’s impact. By iterating with different materials and specifications (with the help of real-time feedback from the carbon analytics tool), the team were able to significantly reduce the element’s carbon impact, reducing the number and length of piles, and switching to driven steel tubes. They then repeated this process with other carbon critical elements, reducing the thickness of the barrier’s apron slab and developing a pre-cast solution for the construction of the three barrier towers.

In total, by leveraging the BIM Analytics – Carbon tool, the team were able to reduce embodied carbon of the barrier structure by 50% against the baseline, exceeding the EA’s targets. These gains were made by focusing on reducing the impact of carbon critical elements, reducing their embodied carbon by an average of 70% and allowing us to tackle the project’s carbon footprint in the most efficient, and most effective, way possible. And all during the initial detailed design process.

This tool has the potential to be a valuable addition to the Eric tool, allowing rapid and easy visualisation of carbon hotspots and significant carbon savings during the design process.

Neil Guthrie; Environment Agency Carbon Manager

The future of carbon reduction

AtkinsRéalis are committed to, not just achieving Net Zero, but using our cross-sector expertise, passion, and global experience to create pioneering solutions that will help our clients rapidly decarbonize, for more sustainable economic growth. The BIM Analytics – Carbon tool forms a key part of this mission, allowing teams to easily assess and reduce their environmental impact, and we are now working with the EA to deploy this technology more widely.

Following our success decarbonizing the tidal barrier itself, AtkinsRéalis have now received funding to deploy the carbon analytics tool across the entire Bridgwater Tidal Barrier Scheme, including the extensive downstream defenses and fish and eel passage improvement works. Detailed design is forecast to be by the end of 2023 with construction forecast completed in 2028/9. We are also working closely with the EA to further integrate their carbon measurement procedures with our tools, so that our carbon analytics can be deployed on even more projects across the UK, helping us deliver more innovative low-carbon solutions. The completed Bridgwater Tidal Barrier will protect over 13,000 homes and 1,500 businesses from flooding caused by climate change related coastal changes and rising water levels. This protection will last for at least a hundred years.