Castle Park Energy Centre
All images are courtesy of Vattenfall Heat UK.
Transforming Bristol’s energy network: Vattenfall and Bristol City Leap
Background
‘Bristol City Leap’ is a world-first approach to decarbonisation at city scale. Bristol City Council was the first UK city to declare a climate emergency in 2018 and set ambitious goals for the council and the city to become carbon neutral.
To help, Bristol City Council procured a private sector partner to form a joint venture that was focused on strategically delivering decarbonisation projects in a joined-up way over a 20-year period, enabling a billion pound investment into Bristol through low carbon energy infrastructure projects.
The council selected Ameresco Limited as a strategic partner to deliver and fund low carbon energy projects across the Council’s estate. This long term partnership is designed to unlock long term strategic planning and investment needed to decarbonise the city.
To specifically decarbonise heating in Bristol, Ameresco brought on Vattenfall Heat UK as an essential subcontractor. As a result, Vattenfall acquired Bristol Heat Networks Ltd – a company originally established by the council in 2019, to develop and operate local heat networks. At the time of acquisition, the company managed three operational networks in Redcliffe, Old Market, and Bedminster, primarily serving council-owned buildings.
This strategic acquisition marked a turning point. Vattenfall brought the scale, investment, and technical capability needed to transform the network from a small, municipally focused system into a citywide, low carbon energy backbone.
In January 2026, the UK Government announced a package of long-awaited regulatory drivers. This includes:
- The Warm Homes Plan – which provides an extension to grant funding for construction
- Progressed heat network zoning – which will bring assured heat demand in pre-determined areas of the city
- Ofgem becoming regulators of the sale of heat – which will bring consumer protection in line with other utilities such as gas and electricity).
This means the Bristol heat network is entering into a new phase of maturity as a regulated utility, with increased measures that support continued development and growth.
Location:
Bristol, UK
Typology:
Citywide heat network
Time frame:
Heat network infrastructure was originally established in 2018 by Bristol City Council, with the first low carbon energy centre coming online in 2022, which is the UK’s largest habour-based water-source heat pump. This existing operational heat network asset was acquired in 2023 by Vattenfall Heat UK, as part of the Bristol City Leap, a world-first public and private sector partnership announced to inject investment into energy systems over a twenty-year period.
Implementation
This transformation is not just about infrastructure – it’s about leadership in climate action. Vattenfall’s work in Bristol is helping to demonstrate how cities can take decisive action on the climate emergency while supporting economic development and energy resilience. Over the course of the partnership, Vattenfall has a large, long term social value commitment which focusses on directing opportunities into the local supply chain, enhancing local skills and providing funding for community energy.
As part of the first phase of the partnership, Vattenfall has committed to:
- Expanding the network – extending the existing buried network assets and developing new network areas, and ultimately interconnecting the areas to create one citywide Bristol heat network.
- Decarbonising all new heat generation – ensuring that every new permanent energy centre uses low carbon technologies such as heat pumps and recovered waste heat.
- Phasing out gas-fired assets – replacing them with low carbon alternatives including water-source heat pumps, air-source heat pumps and capturing excess heat from industrial processes and biomass.
Central Health Clinic is connected to the Bristol Heat Network
Results
Delivering modernised and reliable heating
In 2025, Vattenfall has delivered 18 GWh heat to the 35 buildings in Bristol – including public service buildings, educational institutes, large mixed used developments and residential housing blocks. They also achieved 99% availability of heat across the year which is in line with their commitments under the Bristol City Leap partnership agreement.
Vattenfall has also started constructing a new heat network area in the city centre (the Frome network area) which will unlock a modern heating solution for many more new developments, existing buildings and public service buildings within the heart of Bristol.
Temple Fire Station is connected to the Bristol Heat Network
By 2050, the Bristol heat network has a vision to provide heat to over half of all Bristolians who live, work and learn in the city.
Creating social value in local communities
Alongside delivering and upgrading energy infrastructure, Bristol City Leap has ensured the local community can benefit. A Community Energy Fund was formed and launched, co-funded by Ameresco Limited and Vattenfall Heat UK. As of March 2025, 23 community energy projects have received over £618,000 of grant funding.
The team working under Bristol City Leap has also contributed more than 42.00 hours towards improving communities. The partnership has created 152 local new jobs within Bristol and the wider Bristol area and provided more than 49 weeks of work placements and work experience.
So far, Bristol City Leap has spent nearly £36 million pounds with local suppliers, voluntary community and social enterprise organisations to support the local economy and enable job creation. Bristol City Leap is working up an extensive programme of engagement with education providers – from primary schools to higher education providers to upskill the city’s green economy.
Lessons learned
The following advice has been informed by Vattenfall and is aimed at local authorities who want to promote heat networks in their area and attract developers.
Introduce support planning policy that implement a heat development hierarchy
See Bristol City Council’s 2011 Local Plan Policy BCS14, for an example. This policy required new developments to demonstrate their heat and cooling systems have prioritised connection to existing heat networks over other modes. This strengthens the business case for local heat networks. However, requirements are under review in light of changes to the UK’s National Planning Policy Framework, the emerging Bristol Local Plan, and the UK wide Heat Network Zoning policy.
Publicly procure a long term “Strategic Energy Partner”
Rather than a heat network developer, with other relevant public bodies included as contracting authorities. This allows the successful partner to supply services across your area to all relevant public bodies by direct award. This can increase market interest for a particular network and expedite the delivery and expansion of heat networks. Note that incoming Zoning regulation in England may supersede this recommendation.
Use Local Development Orders to support installation
To support timely installation of heat network infrastructure in appropriate areas, see Bristol Council’s Local Development Order for an example. This creates rights for heat network pipework installation, maintenance etc. on otherwise private developments in order to encourage and facilitate implementation of the network, making the process predictable and efficient.
Promote heat networks that provide opportunity for expansion in the future
For example, the existing network in the Redcliffe area of Bristol was included in the conception of the wider Bristol Heat Networks project. This included opportunities not just to upgrade, but to expand into neighbouring areas and interconnect schemes into one large network.
Provide council-owned land on favourable terms for infrastructure development
Subject to compliance with financial, legal and procurement requirements
Consider if the council has access to heat generation sources
Heat generation sources such as Energy from Waste, waterways, former mining infrastructure etc. and actively look to make these available to heat network developments.
To find out more about the Bristol heat network, visit: