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Cambridge Centre for Smart Infrastructure and Construction

Transforming infrastructure through smarter information




Carbon Reduction Code for the Built Environment Trial Case Study – HS2 Main Works Civils Contract S1 & S2 (London Tunnels)

Chris Hayes, Sustainability Operations Director, Skanska UK Plc



Phase One of HS2 will see a new high speed railway line constructed from Euston to north of Birmingham, where it will re-join the existing West Coast Mainline. Services will travel onwards to places like Manchester, Glasgow, Liverpool, Preston, and Wigan. Phase One will open between 2029 and 2033.

The new line between London and Birmingham will run on 140 miles of dedicated track.  Four brand new stations and two new depots will also be built. 22,000 workers will be needed to complete construction.

Skanska Costain Strabag Joint Venture (SCSJV) is delivering the Main Works Civils Contract (MWCC) for the London Tunnels part of the route (S1 & S2).

HS2 Ltd has determined carbon reduction targets for all contracts. For MWCC, this is set at -50% against the agreed baseline, representing the project as originally tendered.

SCSJV demonstrated carbon leadership from the start, including carbon as a key part of their tender offering, and making a carbon specialist one of the first members of the team straight away upon award of contract. Senior leadership buy-in and support is key. This has been demonstrated through sustainability and carbon sponsorship by the highest ranks of the Project Management Team, signing a statement of endorsement to the Infrastructure Carbon Review, and the creation of a dedicated Sustainability Steering Group featuring senior leaders of the team since early on in the design stage.

SCSJV has been among the first organisations to get PAS 2080 certified as a joint venture in late 2018. The continued PAS2080 accreditation as well as a recently completed independent carbon management review are testament to the solid carbon management processes, in terms of both quantification as well as mitigation, in place within SCSJV.

SCSJV is committed to deliver low carbon outcomes on the HS2 scheme as well as in the wider construction industry as much as possible, and therefore, joined the Carbon Reduction Code initiative to work alongside HS2, the University of Cambridge and other industry partners to help drive this urgent decarbonisation agenda.


Overcoming challenges in implementing the Code

Although HS2 and SCS did not encounter specific challenges in the trial of the Code due to the current carbon reduction commitments of both organisations, there could be issues in the broader development and roll out into existing projects and frameworks. To be successful, it is essential that both clients and contractors, including designers, build carbon arguments into early dialogue, contract clauses and procurement programmes and provide the necessary support to the supply chain to ensure that intended outcomes are achievable.

A lack of internal carbon expertise and resources in supply chains could also hinder the full roll out of the Code. It is imperative that we work as a sector to enable the learning and development at speed, making the requirements for measuring and reporting as simple and as consistent as possible across the built environment.


Implementing the Code - Compromises and opportunities

Some of the requirements within the Code had not been specified in the initial stages of the project, however work to adopt them has begun. In the review of the Code, some of the specific wording wasn’t fully aligned with our current methodologies for the scheme. These would require tweaking to reflect the different and varied contractual arrangements employed as well as the different types and durations of programmes and projects.

For example, the Code doesn’t align well for a joint venture organisation created for a limited duration where long term goals aligned with Net Zero by 2045 don’t apply, unless the client has determined targets for the contract that align to that overarching goal. Therefore, there is potential to look at distinguishing between organisations rather than project level joint ventures or alliances.

The Code also has a requirement to report progress annually, which works very well at an organisational level, allowing trending and a low carbon trajectory to be followed in a linear way. However, an individual major project would not follow that pattern, an S curve or Bell Curve for carbon (starts low, builds up with programme and then tails off towards the end) would be a more common trend. On this basis, percentage (%) reduction targets against a baseline would only be applicable if achieved at the end of the scheme and monitoring of progress during these targets during project delivery would be quite complex. This type of forecasting and reporting at a project level is still very much in its infancy.


Lessons learned

Upon review of the Code, it appears that it would enable greater clarity on carbon reduction responsibilities for all parties in the delivery of programmes and projects. These have been covered in part previously in some industry specific guidance and recommendations, however they have not been delivered against consistently in the major projects sector by all parties, which this process should encourage.

Greater clarity from commitments targeted to client, designers, principle contractors and supply chain may improve the visibility of carbon requirements across the board and encourage all parties to commit to and deliver against these responsibilities, In this case the carbon management processes are aligned and certified to PAS2080, providing a structure for addressing the Code.

Some of the solutions, such as an industry standard and database that would be required to draw comparisons across projects and sectors alike, will need to be developed, owned and made accessible to the industry for the Code to deliver a collaborative, industry wide approach to carbon reduction.


Next steps

For the industry to achieve Net Zero carbon, the whole value chain must act collaboratively, with low or zero carbon as a common goal or outcome. Often large infrastructure clients such as HS2, and principal contractors, such as SCS, have the expertise in house to work towards that goal. However, the extended value chain that are necessary for the successful delivery of Net Zero may not.

It is essential that we enable the skills and specialist knowledge in the full value chain that allows them to effectively contribute to Net Zero schemes.  How we engage and procure will be critical to that collaboration and engagement.

Following the development and review of the Code within HS2 and SCS, we will now engage, work with and support our extended supply chain to test the Code. We need to understand the potential risks and opportunities the Code will have and any potential unintended consequences from how it is applied part way through a scheme.  

We will be able to use these findings to further refine the Code, and our own procurement and delivery systems, to better engage and work with suppliers to achieve the current and future targets for a low carbon High Speed Two project.