23 September 2026
New low-carbon energy network will provide sustainable heating and cooling to homes, businesses and hotels across Marble Arch and Marylebone
Today, The Portman Estate announced it has secured £11.4 million from the Department for Energy Security and Net Zero’s Green Heat Network Fund to support the development of the Marble Arch Energy Network [MAEN], a pioneering low-carbon energy system for central London.
The network will provide sustainable heating and cooling to landmark retail spaces, offices, hotels and homes across the Marble Arch and Marylebone area, helping to reduce carbon emissions, improve energy resilience and support the long-term sustainability of the neighbourhood.
The network is expected to provide heating and cooling to at least 34 major properties initially with plans to expand further over time. Once operational, it is expected to deliver 39 GWh of heating and 25 GWh of cooling each year – that is enough low-carbon heat to meet the annual heating needs of around 3,000 average UK homes.
As a B Corp Certified company, this ambitious programme of work is part of The Portman Estate’s commitment to reaching net-zero greenhouse gas emissions (GHG) across its value chain by 2045. The network is designed to supply The Portman Estate’s highest energy buildings with most of their heating and cooling needs by using local and renewable energy sources. The network will help buildings prepare for the new statutory regulation of heat networks by Ofgem and the introduction of heat-network zoning in England, while enabling them to share surplus heating and cooling, reduce energy waste and cut carbon emissions.
How does it work?
The proposed network will harness renewable energy from London’s natural chalk aquifer beneath the city. The ground water within the aquifer remains at a stable temperature throughout the year. Water will be drawn from the aquifer and used with heat-pump technology to provide heating and cooling, before being safely returned back to the aquifer.
By connecting multiple buildings to a shared energy network, surplus heat or cooling can be used more efficiently, reducing energy waste, lowering utility costs and cutting carbon emissions.
“Graphic taken from “Marble Arch Energy Network: Exploring a 5th Generation District Heating and Cooling network in the Marylebone area”, a film produced by Chocolate Films (2026) for The Portman Estate.”
The Benefits
MAEN is expected to reduce carbon emissions from connected buildings by up to 98%. It will also strengthen local energy security in an area where individual building decarbonisation can be challenging due to the historic nature of many buildings, limited space for plant equipment and pressure on the electricity grid.
The funding will enable The Portman Estate to move the project into its next phase, including securing a long-term delivery partner to finance, design, build and operate the network. The project is also expected to support nearly 200 jobs, apprenticeships, and training opportunities both locally and nationally.
Over time, the network could expand beyond the initial phase to provide clean, reliable energy to a wider area of the West End.
Simon Loomes, Strategic Projects Director at The Portman Estate, said: “We are delighted to receive support from the Green Heat Network Fund for this transformative project. The Marble Arch Energy Network represents a once-in-a-generation opportunity to modernise essential infrastructure within one of London’s most important mixed-use districts. The project will help create a more resilient, efficient, and sustainable energy system for businesses, residents, hotels and retailers, while supporting the long-term competitiveness of the West End. By unlocking investment in shared energy infrastructure, MAEN demonstrates how historic urban neighbourhoods can adapt successfully to future environmental, economic, and energy challenges. It forms a central part of The Portman Estate’s long-term stewardship strategy and our commitment to ensuring a thriving district for future generations.”
Charlotte Large, Director of Clean Energy and Heat Networks, Westminster City Council said: “Westminster City Council welcomes the Green Heat Network Fund’s support for the Marble Arch Energy Network. Decarbonising existing buildings in central London is one of the greatest challenges facing cities on the path to net zero. MAEN has the potential to make a significant contribution to reducing Westminster’s carbon emissions while improving local energy resilience and supporting sustainable growth. The Council looks forward to continuing its collaboration with The Portman Estate and project partners as the scheme progresses.”
The full film detailing how the MAEN will work can be found HERE
