Plans have been unveiled to build the UK’s largest heat network capturing heat from the River Thames, London Underground and sewer networks to warm around 1,000 buildings in central London, including the Houses of Parliament.

Drawn up by Department for Energy Security and Net Zero and consultant Aecom, the £1bn scheme will be delivered by a joint venture between leading players in the heat network market Vital Energy and Cumbria-based Hemiko.

Known as the South Westminster Area Network (SWAN), the phased project is expected to deliver first heat as early as 2026, with the network due to be entirely connected and complete by 2050.

The scale and complexity of the project makes it the most significant heat network scheme designed in the UK.

Buildings in the area served by the heat network could save 92 % of CO₂ emissions compared to current levels and, by 2040, the scheme could help save Westminster 75,000 tonnes of CO₂ each year, which is the equivalent to 1.2 million trees.

The network will stretch from Victoria Station up to Temple Underground Station near the Strand, bounded by St James’ Park and the River Thames.

Map of buildings to be hooked up to heat supply network in Westminster

Channa Karunaratne, head of heat networks at AECOM, said: “The size and ambition of SWAN demonstrate how to drive decarbonisation at a city-scale, and it is a trailblazer for how our cities can operate more sustainability.

“Westminster is one of the most recognisable locations in the world and through SWAN, the political engine of the UK is going to be supplied almost entirely with low-carbon heat for the first time.

“Since SWAN’s inception, we’ve worked in partnership with DESNZ to commercialise the scheme and accelerate private investment.

“Reaching today’s milestone with the appointment of Hemiko and Vital Energi is a proud moment for our team and an important step forward for this ambitious project that is helping to secure a low-carbon future for London.”

Toby Heysham, CEO of Hemiko and spokesperson for SWAN said: “Heat networks are the next big utility in the UK, and we are investing £1bn over the next 6 years into networks that will allow local people and businesses to make use of locally wasted heat.

“This network will be the flagship network in the UK, the first new zonal scale network in a market that offers an investment potential the size of the UK offshore wind industry. Steps like this show that the UK heat networks market is open for business.”

Aecom’s work has been supported by HermeticaBlack, specialists in the investment, development and asset management of net zero projects, and specialist infrastructure financial advisory firm Asteros Advisers.