The London Borough of Hounslow is on a mission to achieve net-zero carbon emissions by 2050, with a mandate for council-owned assets to decarbonise by 2030. We took on the challenge of developing a masterplan district energy scheme of unprecedented scale, which is proposed to deliver heat across the entire borough and help the borough achieve its ambitious sustainability goals.

We identified six clusters within the borough with high energy demand density. The primary objective was to find innovative ways to decarbonise these areas effectively, cognisant of local authority buildings, social housing, and private entities.

Heatmapping and Demand Assessment:

We initiated a comprehensive heat mapping exercise to pinpoint suitable buildings and sites for connection to a district energy network. This revealed an astounding potential demand of over 300 GWh of heat, signifying a significant opportunity to reduce carbon emissions.

Stakeholder Collaboration:

Collaboration with key stakeholders – Thames Water Ventures, Heathrow Airport, and the NHS – played a critical role in the project. This collaboration enabled a deeper understanding of the economic and environmental impact of the proposed scheme, ensuring it aligned with sustainability and financial objectives.

Innovative Approach:

Our ambitious approach extended to creating a borough-wide network, entailing a £250+ million capital expenditure and spanning a network length of 60+ km. This extensive network seamlessly connected five of the six identified clusters, capitalising on ambient heat from the TW Mogden sewage treatment works, which possesses the capacity to supply heat for the entire borough and beyond.

Social Responsibility:

Recognising the significance of social housing within the proposed network, we ensured a comprehensive understanding of the network’s implications. This involved carefully balancing the imperative of decarbonisation with safeguarding customers from energy poverty. We also took the opportunity to reach out to the community and undertook a series of STEM and decarbonisation education workshops with local schools.

Environmental Impact:

Upon completion (expected in 2035), the network is estimated to have saved a lifetime carbon emission of ~2,900 ktCO2e over 40 years, of which ~1,800 ktCO2e would be in-borough. To put this into perspective, it’s equivalent to the carbon emissions saved from approximately 1.3 million round-trip flights from London Heathrow Airport to JFK Airport.

For more information about the project please visit the council’s website, and you can download the full report here.

Client: London Borough of Hounslow


  • District energy network design
  • Energy master planning
  • Load profiling
  • Heat, cool & power mapping
  • Heat network feasibility