City of London Corporation – a retrofit first approach

At the forefront of London’s fight against climate change, the City of London Corporation (the City) has adopted a ‘retrofit first’ approach as part of a climate action strategy to reach net zero by 2040. Juggling the need to achieve both net zero and accommodate the provision of 1.2 million sqm of commercial floorspace by 2040, the City has sought to strike a balance between an uplift in commercial floorspace and the associated embodied carbon emissions. As a result, this has led to a number of office-led refurbishment schemes retaining at least 50% by mass of the existing building superstructure, and other building fabric which previously would have been demolished.

Such approaches are here to stay, with the Draft City Plan 2040 prioritising retrofitting of existing buildings leading to the establishment of a ‘retrofit fast track’ for office development which retains the majority of the superstructure of the existing building.

Planning for sustainability – a new SPD and what it means for development

Adopted on 19th February 2025, the Supplementary Planning Document (SPD) Planning for Sustainability provides a framework for how to approach the City’s climate resilience policies and how to achieve good practice, design and construction through the following five themes:

1) Retrofit and reuse

Adopting a retrofit first approach, the City promotes reuse of existing building stock with early identification of the most suitable approach to developing a site which can range from light retrofit to deep retrofit with extension. Defined as ‘the upgrading of a building in relation to the installation of new building systems or building fabric to improve efficiency, reduce environmental impacts and/or adapt for climate change’, retrofit within the City must retain and reuse at least 50% of the existing building(s) superstructure (by mass).

2) Greenhouse gas emissions and energy use

The City provides guidance on how to reduce whole life carbon emissions through both the development and construction process, and day-to-day operation. In the instance of commercial development, this had led to the implementation of the NABERS UK scheme which focuses on operational energy use, with office development required to achieve a rating of 5* for new buildings and 4* for retrofit projects.

3) Circular economy principles

Promoting a circular construction model where materials are retained in use, reused and recycled, the City is targeting zero construction and operation waste through the adoption of a long-life, loose-fit and low-energy approach both to existing and new buildings and associated materials. This is set to be achieved through alignment with the Greater London Authority’s embodied carbon benchmarking and recommended third party review. Where targets are not achievable, they must be proportionately outweighed through wider environmental benefits.  

4) Climate resilience

The City set out that context specific climate resilience principles should be appropriately considered during RIBA Stages 1-3. This includes an assessment of built-in resilience through overheating risk assessment, making use of future weather data sets.

5) Urban greening and biodiversity

Following mandatory biodiversity net gain and urban greening requirements, developments should seek to improve biodiversity and urban greening through the implementation of high-quality greening in both open spaces and on buildings. Whilst the majority of existing buildings within the City will fall into the de minimis exemption, the City is set to introduce a policy requirement for all major developments to target a score of three biodiversity units per hectare.

Building upon existing guidance such as Carbon Options Guidance (2023) and Heritage Building Retrofit Toolkit (2024) the new SPD demonstrates that retrofit projects will be heavily favoured in the planning process, with all development expected to deliver wider sustainability benefits.

Wider Central London approach

Other Central London boroughs, including Westminster and Camden, are continuing to develop policy and guidance which prioritises environmental sustainability, highlighting a growing awareness of the need to appropriately address climate change through the built environment.

Within Westminster, an updated Environmental SPD (2024) provides further guidance on how to interpret and implement relevant policy. Currently undergoing consultation until March 2025, the Westminster Environmental SPD adopts a similar approach to the City, prioritising building retention through consideration of how retrofit or refurbishment measures could reduce construction related carbon emissions. Beyond broader climate resilience strategies, other priorities of the SPD include embedding circular economy principles in the design process and associated consideration of whole life carbon impact.

Similarly, in the Draft New Camden Local Plan (2024), Camden within its environmental sustainability-specific policy is proposing the introduction of a condition and feasibility retrofit first approach for development of sites with existing buildings early on within the design process. If adopted, partial or substantial demolition of existing building(s) would only be permitted where it can be demonstrated that comprehensive exploration of sustainable alternative development options are not feasible.

Further information

Contact Poppy Heneghan-Pickard or Lida Sykara