Zero Carbon Accelerator

RE:FIT5: The Mayor of London’s new energy performance contracting framework for public sector decarbonisation

News · 18 Nov 2025

Solar Power Station over Canary Wharf, London. London skyline in the background

The Mayor of London is launching RE:FIT5 (2025–2029) in January 2026, an improved national framework designed to help public sector organisations decarbonise their buildings efficiently and affordably.  

RE:FIT5 builds on over a decade of success, offering a trusted route to guaranteed energy and carbon savings. This performance-based contracting framework helps public sector organisations to deliver decarbonisation and retrofit projects with guaranteed energy and carbon savings. It supports the aggregation of projects to scale up the impact and build long-term partnerships with service providers.  

Importantly, organisations can access flexible financing options through RE:FIT5, including off-balance-sheet Energy Performance Contracts, grants, and internal capital. The Mayor of London’s Zero Carbon Accelerator will offer comprehensive, end-to-end support to public sector organisations in London seeking to use the RE:FIT 5 framework. The Accelerator will deliver free technical, commercial, and procurement assistance throughout the process. 

What organisations and projects can RE:FIT5 support? 

RE:FIT5 is available to all public sector bodies, including central and local government, health, education, and cultural institutions. While the framework itself is open to all, the Zero Carbon Accelerator’s free end-to-end support is exclusively available to public sector bodies based in London. Organisations outside London are welcome to use the framework, but they would need to fund any technical support independently.  

RE:FIT5 covers domestic and non-domestic retrofits, with framework service providers using a wide range of technologies such as: 

  • heat networks 
  • heat pumps 
  • solar panels 
  • energy-efficient lighting 
  • BMS controls 
  • glazing 
  • insulation 
  • electric vehicle charging points  
  • infrastructure 
  • power purchase agreements. 

 It also includes grant management, funding applications, and asset management services. 

Impact of previous iterations of REFIT 

RE:FIT has supported 220 public sector organisations across London, including the London School of Economics, Transport for London, NHS trusts, universities, and boroughs.  

During this time, the framework has helped retrofit 1,200 sites, channelling £269 million of capital investments into retrofit projects. This has helped save 56,000 tonnes of CO2, reduce energy consumption by 207GWh and £14.5 million for the public sector each year. These projects have helped save 420,000 tonnes of CO2 in total.   

How is RE:FIT5 different to previous versions of the framework? 

The GLA has made improvements to RE:FIT5 to help public sector organisations decarbonise more easily and efficiently, including: 

  • faster procurement with the option for direct award 
  • improved quality through RIBA stage 4 thresholds for Investment Grade Proposals 
  • greater transparency through open-book obligations 
  • carbon valuation using UK Emissions Trading Scheme standard 
  • enhanced safety reflecting post-Grenfell building regulations 
  • greater affordability facilitated by Energy Performance Contracts to achieve off-balance sheet solutions 
  • stronger social value requirements (inclusion, equality, skills) 
  • independent measurement and verification for performance/savings assurance. 
  • easier access to the framework through the Zero Carbon Accelerator Expression of Interest process. 

What is the process of getting support from RE:FIT5? 

Start your journey with RE:FIT5 by submitting an Expression of Interest. You will then need to fill out a Self-assessment form, sharing more details about your estate and energy data to help us determine what opportunities there are to decarbonise your buildings. 

Once we have determined what support is needed, you can access RE:FIT5 Invitation to Tender templates to either run a mini-competition or direct award to a supplier. This will result in the delivery of an Investment Grade Proposal (IGP) which confirms the final costs of the retrofit or decarbonisation, the guaranteed energy/carbon performance, savings, payback, final designs, detailed measurement and verification plan. After you select a preferred bidder, the works contract is finalised based on the IGP.  

From there the project moves into delivery, with construction and commissioning overseen to ensure guaranteed savings are achieved, backed by independent measurement and verification. 

How is the Zero Carbon Accelerator supporting organisations? 

The Zero Carbon Accelerator provides free end-to-end expert support to public sector organisations in London who wish to use the RE:FIT5 framework to decarbonise their estate portfolio/buildings. Support available includes: 

  • Pre-procurement support: 
    • feasibility studies 
    • energy audits 
    • early market engagement  
    • business case development. 
  • Procurement support: 
    • tender development 
    • high level appraisal evaluations 
    • contracting  
    • Investment Grade Proposals (IGP)/measurement assessment.  
  • Post-procurement support: 
    • energy conservation measures installations 
    • measurement and verification (M&V) review. 

Ready to get started with RE:FIT5? Submit an Expression of Interest to access the framework. 

You can also explore the latest funding and finance opportunities to help bring your net zero projects to life.

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