City of London Planning for Sustainability SPD: A Developer’s Guide to Compliance

The City of London Corporation has formally raised the bar for sustainable development. With the adoption of its Planning for Sustainability Supplementary Planning Document (SPD), environmental performance is no longer just an aspiration – it’s a core planning requirement. 

Adopted on February 19, 2025, the SPD sets enforceable expectations for how developments in the Square Mile must address whole life-cycle carbon, retrofit and reuse, circular economy principles, climate resilience and urban greening. Compliance now requires earlier analysis, deeper technical coordination and the right specialists from day one.

This guidance is relevant for developers as well as asset owners, architects and design teams submitting planning applications in the City of London, particularly for commercial office, retrofit and mixed-use developments.

What Is the City of London Planning for Sustainability SPD? 

The SPD provides detailed guidance on how planning applicants must demonstrate environmental sustainability. It’s a material consideration in determining applications, and applies to: 

• New-build developments
• Major refurbishments and retrofits
• Extensions and alterations
• Public realm and open space works 

Both major and minor developments are affected, with more extensive documentation required for larger or more complex projects.

Retrofit-First Planning Policy in the City of London 

A defining feature of the SPD is its clear “retrofit first” direction. Developers are expected to: 

• Assess the reuse of structures, façades and materials.
• Justify demolition through early optioneering, comparative assessment, whole life-cycle carbon analysis and circularity assessments. 
• Demonstrate that retrofit options were meaningfully explored. 

In practice, retrofit and reuse are now the baseline for sustainable development in the City of London, not alternatives to new construction.

Whole Life-Cycle Carbon Requirements For Planning Approval

The SPD formalizes whole life-cycle carbon assessment (WLCA) as a planning requirement. Submissions must address: 

• Embodied carbon from materials and construction.
• Operational emissions over the building’s life
• End-of-life impacts, including deconstruction/demolition and disposal 

Critically, carbon analysis must be undertaken early enough to shape façade and structural systems, material selection and construction methodology. Designing first and justifying later is no longer sufficient.

Circular Economy & Material Efficiency 

The SPD advances circular economy principles beyond waste reduction. Developers are expected to demonstrate: 

• Reuse of materials where feasible.
• Design for adaptability and future change of use.
• Reduced reliance on virgin materials and construction waste.

Delivering these outcomes requires early engagement and coordination across design/engineering, construction and sustainability disciplines. 

Climate Resilience Requirements in City of London Planning

Sustainability under the SPD extends beyond emissions. Planning submissions must also address:

• Overheating mitigation in dense urban environments
• Flood risk and sustainable drainage systems (SuDS) 
• Water efficiency and resource management
• Biodiversity Net Gain & Urban Greening Factor 

What Developers Should Do Now 

To meet the City of London’s sustainability planning requirements, developers should: 

• Integrate sustainability and carbon strategy at project inception.
• Undertake early retrofit and reuse feasibility studies and carbon optioneering.
• Complete robust whole life-cycle carbon modeling.
• Align submissions with SPD and City documentation requirements.

Projects that defer these steps risk redesign, planning delay or refusal. 

While the City of London is among the most explicit in codifying these requirements, it’s not alone. Other U.K. authorities, including Westminster, Camden, and Bath and North East Somerset, have adopted or are advancing similar policies focused on whole-life carbon, retrofit-first strategies and climate resilience, reinforcing a clear national shift in planning expectations. For example, Preoptima's PACER (Planning Application Carbon Evaluation and Reduction) tool, developed in collaboration with Westminster City Council and funded by Innovate UK, is available for use and designed to help local planning authorities (LPAs) manage, review, and enforce carbon reduction policies for new building projects.

How Thornton Tomasetti Supports SPD Compliance 

With a London-based team and global leadership in sustainable design, Thornton Tomasetti supports developers navigating the City’s evolving planning landscape. Our work spans: 

• Sustainability and planning strategy 
• Embodied carbon assessment and reduction 
• Whole life-cycle carbon analysis and circular economy assessments 
• Retrofit-first structural and façade solutions
• Climate resilience and Climate Action planning 

Our work on projects such as Stonecutter, one of London’s most sustainability-driven commercial developments, demonstrates how ambitious environmental targets can be achieved without compromising performance or value. 

Contact us for help designing high-performance & low-energy solutions for your facilities and communities