International Construction Law Review
DECARBONISATION MECHANISMS IN CONSTRUCTION LAW: FROM THE CHANCERY LANE PROJECT TO NEC OPTION X29 AND FIDIC CARBON MANAGEMENT GUIDE
Andrea Costanzi*, **
Senior Manager – International Contract Management, Webuild
“We are the first generation to feel the impact of climate change and the last generation that can do something about it.” Barack Obama (UN Climate Change Summit, 23 September 2014)1
ABSTRACT
The contractual treatment of decarbonisation in construction is shifting from aspirational provisions to enforceable, auditable obligations embedded in standard forms. This article traces that evolution from The Chancery Lane Project’s Net Zero clauses, which pioneered climate-aligned drafting techniques in a soft-law context, through the transitional JCT 2024 sustainability clauses to NEC Option X29 and FIDIC’s newly released Carbon Management Guide and Carbon Emissions Guidance, launched at the end of 2025. It focuses on how the NEC and FIDIC regimes convert climate policy into clear contractual duties and measurement and reporting rules, link carbon performance to price adjustments, and interface with limitation of liability, relief events and risk allocation.
* Andrea Costanzi, Italian qualified lawyer, is Senior Manager in the International Contract Management Department at Webuild SpA. A long-standing member of the European International Contractors’ Working Group Contract Conditions, he has long been engaged in doctrinal and comparative analysis of international construction contracts; his latest research focuses on sustainability obligations and the incorporation of Net Zero clauses into contractual frameworks and standard forms.
** Selected elements of this article were developed and presented by the author across academic and professional venues throughout 2024–2025 (in chronological order): CICA – EIC Conference – Promoting collaborative and innovative approaches for an efficient delivery of resilient and sustainable construction projects (26 November 2024, Paris); CICA–NEC Webinar – Introducing the Climate Change Clause Option X29 (12 December 2024); FIDIC Webinar Series – Integrating Carbon Management into FIDIC Contracts (30 October 2025) and FIDIC International Contract Users’ Conference, London (1–4 December 2025), including the launch of the FIDIC Carbon Management Guide. The author gratefully acknowledges the constructive feedback received in these fora, and thanks the hosting institutions (Confederation of International Contractors’ Association – CICA, European International Contractors – EIC, FIDIC, NEC) together with all fellow panellists and discussants with whom the author had the privilege of sharing the stage over these two years’ work and constructive discussions on decarbonisation clauses.
1 Originally attributed to Governor Jay Inslee.
Pt 2] Decarbonisation Mechanisms in Construction Law
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