Biomass District Heating | Duffryn

Newport City Homes

Since 2014 Sustainable Energy Ltd has progressed three key projects for the decarbonisation and improved efficiency of the Duffryn heat network with Newport City Homes (NCH), a large housing association providing services to more than 10,000 residents, leaseholders and shared owners in the city of Newport.

Renewable heat:

In 2014, Sustainable Energy Ltd was contracted to provide detailed design, tendering, commissioning management and RHI application support for what would become the largest biomass district heating scheme in Wales. NCH constructed a biomass energy centre to house the 2,500 kW biomass boiler, which integrates into the existing 970-home district heating scheme in Duffryn, Newport.  This project was delivered in partnership with British Gas, under the ECO funding scheme and removed oil boilers to make significant carbon reduction.

Heating system upgrades:

Following the switch to biomass heat supply to the Duffryn network, in 2017 a further improvement was implemented to reduce temperatures and increase efficiency of the heat network. Sustainable Energy Ltd was appointed by NCH to design, specify, procure, and supervise the construction of the refurbishment of all dwellings on the network, which included new radiators and heat interface units in each property which was all installed by Gibson STS. The new design allowed temperatures and flow rates to be reduced, following which a new BMS was installed and network pump sizes were reduced, to optimise the network operation.

Heat network replacement:

In 2023 the buried pipework that had provided nearly 50 years of service was in need of replacement and Sustainable Energy Ltd was appointed to review and redesign the new network. The network is a hybrid of steel and polymer pipe which was resized to improve the overall efficiency of the scheme (in response to the reduced heat demands of the network following the heating system upgrades). Sustainable Energy Ltd supported NCH to secure a £3.7m HNES grant and to procure the contractor Vital Energi to install the new network, which was completed in May 2024. The new heat network will provide heat supply to the estate for another 50 + years ensuring renewable heat at the lowest cost.


Sustainable Energy Ltd has acted as lead consultant, designer and client engineer for all developments and improvements to the Duffryn heat network over the last 10 years, taking it to best practice for heat networks and renewable heat. This has included design for the biomass boiler energy centre, supporting the tendering process and construction of the project through to handover, design of new dwelling heating systems, HIUs and metering through to commissioning management, heat network design, funding support, procurement, supervision and client engineer. Sustainable Energy continues to support NCH with network efficiency and optimisation including controls modifications.

Technology Solution:

The energy centre comprises a 2,500 kW Polytechnik wood chip boiler with 240 m³ fuel store, which allows it to receive a daily articulated lorry volume of sustainable, local, woodchip. Thermal storage of 50,000 litres allows the biomass boiler to deliver heat to the district heat network efficiently and consistently. Three 1,500 kW gas boilers provide energy for backup and peak heat demand conditions.

The system includes an electrostatic filter, ensuring emissions are minimised to the lowest feasible levels. Full integration of the biomass and gas boilers is aided by a comprehensive control and monitoring system.

The heat network comprises 3.5 km of pre-insulated steel and polymer buried pipework which connects 29 substations which in turn supply Danfoss SAV direct heat interface units and heating systems that operate at temperatures of 70/40C. Metering and billing is provided by Switch 2 using the G6 pre-payment system.