Brent Cross Town Primary Substation
Project summary: Substation screen for a large mixed used redevelopment in North London.
Location: Brent Cross, London
[Image: credit John Sturrock]
Project type: Industrial
Size: 21m high 115m circumference steel structure
Completion: Steel works started in July 2022 and were completed in November 2022.
- Brent Cross South Limited Partnership – Joint Venture between Related Argent and the London Borough of Barnet (client)
- Galldris Group (main contractor)
- IF_DO (architect)
- Arup (concept structural engineer)
- Whitby Wood (structural engineer)
- Bourne Special Projects (steel structure designer, fabricator, and steel erector)
- Cleveland Steel & Tubes (reclaimed steel stockholder and supplier)
- Brent Cross Town is one of the largest urban regeneration projects in Europe. Brent Cross Town required a new 80MVA substation to provide renewable electricity to the new development, including the 6,700 new homes, 3 million sq ft of offices and new retail and leisure spaces. The substation equipment was designed to be enclosed in a 21m high 115m circumference oval screen in colourful colours, serving as a piece of public artwork.
- Arup proposed the idea of reusing steel, recognising that steelwork was the largest element in the project. They organised a sustainability inception meeting with the client, who supported this suggestion in line with their goal of achieving carbon neutrality by 2030. The concept of steel reuse was also supported by the architect and the rest of the team.
- Around 45% of the total designed steelwork was reused in this project leading to around 40% carbon savings. Reclaimed steel tubulars were selected for the long columns of the structure, while virgin steel was used for the façade support, where tubes would have been less efficient and clunky for connections.
- Reclaimed tubes were purchased from stockholder Cleveland Steel and Tubes and originated from cancelled projects in the oil and gas industry.
Key drivers for steel reuse
The concept of steel reuse was brought forward by Arup and was strongly supported by the client in line with their circular economy and carbon emissions reduction goals.
Reclaimed steel procurement route: Reclaimed steel was purchased from stockholder Cleveland Steel and Tubes.
Information available on reclaimed steel: Steel has originated from surplus oil and gas pipeline projects.
Quality of reclaimed steel, testing and certification: Supplied tubulars were in excellent ‘as new’ condition. The steel was independently tested and weld inspected in accordance with the SCI P427 protocol.
Warranty issues: The reclaimed steel was CE/UKCA marked, so no warranty issues were incurred.
Cost of reclaimed steel versus new steel: A cost analysis conducted in 2021 showed that the cost of reclaimed material per tonne was 50% lower than new steel. Considering the additional costs of testing, surface preparation and transportation the cost of reused steel was 25% lower than new steel.
Economical implications of steel reuse: Steel reuse resulted in economic advantages for the project. There was a sharp increase in commodity prices during the project timeline: the price of new steel had almost doubled. However, this did not affect the project’s viability as the reclaimed steel was procured early in the project.
Implication of steel reuse on project timelines: Steel reuse did not have any implications on project timelines.
Lessons learned, challenges and critical success factors
- The design process with reclaimed steel was straightforward and similar to the usual process, with three important aspects highlighted: assuring the availability of reclaimed sections, design efficiency, and early engagement with suppliers. The design team engaged with stockholder Cleveland Steel and Tubes early on to determine the selection of available reclaimed steel sections, which were well suited for this project.
- Design efficiency was a key consideration to avoid using larger sections than required due to the limited availability of reclaimed stock. In some cases where reclaimed steel was not optimal, virgin steel was selected, as in the use of virgin steel for the façade support, which was more efficient and less clunky for connections.
- Early engagement of the supply chain is crucial, and in this project, the reclaimed steel supply was reserved through the stockholder during RIBA Stage 3, and early orders were placed in Stage 4. This approach ensured that the material suppliers were aware of the client’s requirements and could find and hold the appropriate materials for the project. The steel contractor was appointed at the end of Stage 3, giving them enough time to conduct due diligence on the material.
- If the material is to be pre-sourced, then it is critical that the design is finalised, or the design parameters are fixed. Steel design is complex involving architects’ design, steelwork design and connection design, all of which can be conducted by different parties. In this project, the design underwent changes, and the structure was value engineered purely on a weight and cost basis, so some of the pre-sourced reclaimed steel became irrelevant.
- Effective communication between the design team and the supply chain is crucial, particularly in steel design where concept design, steelwork design, and connection design may involve different parties. In this project, although the initial designs were provided to the project team, subsequent changes made by the steel structure designer were not effectively communicated to the steel supplier. Consequently, the reserved steel did not match the updated design, and virgin steel had to be sourced, resulting in a missed opportunity to save 22 tonnes of embodied carbon. Additionally, despite the steel being independently tested and weld inspected according to the SCI P427 protocol, certain channels with pre-existing holes and varying lengths were not selected due to concerns of extra work and potential dimensional clashes.
- Specifying and encouraging steel reuse in the supply chain is essential to prevent ‘buyer inertia’ and ‘business as usual’. In the project, the team had to overcome cost estimation barriers and persuade the steel fabricator to use reclaimed steel. Championing steel reuse was crucial for the project’s success.
- The construction site did not have space constraints which made the design and coordination with steel reuse easier, which could have been more complex for a project with constrained space.
This case study was compiled based on interviews with Related Argent, Cleveland Steel and Tubes, Arup, and published data, as part of the DISRUPT project (Delivering Innovative Steel ReUse ProjecT).
- Related Argent. 2022. Brent Cross Town Primary Substation. [Poster]. Circular Steel, 30 June 2022, London