We have been working with Leeds City Council to develop a low carbon energy solution connecting 1,983 properties and numerous businesses to an efficient district heating network.
Leeds City Council have ambitions to improve air quality in Leeds and reduce the City’s carbon emissions, whilst also providing their council tenants with more reliable and lower cost heating. They sought an energy solution that would meet these goals and provide a low carbon and resilient energy supply for their most vulnerable tenants.
With funding assistance from West Yorkshire Combined Authority, Leeds City Region Enterprise Partnership and the European Regional Development Fund (ERDF), the council have invested £35m into connecting 1,983 properties and numerous businesses to an efficient district heating network. We are providing the design and build services for the solution, and the operation and maintenance services for the HIUs within the multi storey flats for 5 years and the district heating network and energy centres for 12 years. By constructing two new energy centres, our solution will reduce carbon emissions by 22,000 tonnes per year, and reduce fuel bills by between 10-25%.
We designed a solution whereby an energy centre at Cross Green would harness steam from the Veolia operated Recycling and Energy Recovery Facility (RERF), converting it into low temperature hot water and feeding it through a 16.5km district heating network to supply heat and hot water for 26 apartment blocks and businesses. This is expected to grow organically as new developments connect to the first phase and by building significant extensions to growth areas. The scheme also includes the construction of an additional energy centre at Saxton Gardens that will act as an energy top-up and back-up to provide additional resilience for the network.
Performing value engineering to identify efficiency improvements
The project was initially procured as two separate schemes, and as the winning tenderer for both, we were able to create a hybrid solution. We analysed the concept design created by the client’s design team which initially consisted of two independent district heating networks with an energy centre at Cross Green containing equipment to utilise the waste steam from the RERF and with additional equipment to function as back-up, along with various satellite back-up boiler houses along the networks. By looking at the two proposals together, we were able to identify areas to generate greater network efficiency and financial savings, as well as shorten construction timescales. Once under contract, we agreed design changes that combined the two networks into one singular network. This featured a main energy centre at Cross Green and a resilience energy centre at Saxton Gardens, taking away the need to include additional plant rooms containing gas-fired plant. This reduced the requirement for additional construction, plant and utility applications, and in turn reduced the capital expenditure of the project by 12.5%.
Impressing the client with a high quality tender proposal
We were favoured by the Council due to presenting designs of a high standard which resulted in our bid being a success. The quality scoring of the tender was at a ratio of 60% design and 40% pricing meaning that there was preference to a strong design over the lowest cost bid. A scoring ratio like this allows for higher quality designs to prevail, resulting in an overall more beneficial and reliable solution. It was a three stage tender programme which allowed us to analyse the project as a whole to present a stronger design.
Additional network resilience through a fully equipped back-up energy centre
The Cross Green energy centre will act as the interface between the RERF and the Leeds PIPES heat network and is equipped with distribution pumps, two 100,000 litre thermal stores and associated controls systems. It will convert the 20MW of steam from the RERF into Low Temperature Hot Water which will be pumped along the transmission line, passing through to the Saxton Gardens energy centre.
The Saxton Gardens energy centre will provide resilience to the network. The location was chosen following the removal of the satellite boiler-houses that formed part of the original multi-storey flats proposal. This benefits the network as it minimises the length of pipe required and reduces the risk of future issues. As the location of the Saxton Gardens energy centre is further along the network than some of the identified future connections, we devised a system to allow a back-feed to serve these future zones should the Cross Green energy centre go offline.
We completed a load analysis of the minimum and peak energy demands to ensure the Saxton Gardens energy centre is fully equipped to manage the peak 33MW of consumption, and provide spare equipment should there be any failures. The equipment required includes four 11MW gas-fired boilers, two 750kW modular gas boilers, four expansion vessels, four distribution pumps and a 20m high multi-core chimney that were all sized accordingly based on the load analysis, noise and emissions surveys carried out.
Our design has been developed using specialist collaborative 3D modelling of the two energy centres for all disciplines including architectural, structural and M&E services, which enabled the identification and resolution of any issues with the operation of the equipment prior to construction commencement.
One of the largest district heating networks in the UK
The Leeds PIPES scheme will connect 1,983 properties and businesses in Leeds over 16.5km of pipe making it one of the largest district heating networks in the UK. This is only the first phase of a potentially larger network as it has been designed with the ability to expand and make additional connections. We have achieved this through sizing the energy centre equipment to cater for additional loads and by providing capped pipe ends to ease future extensions. Designed with pre-insulated pipe with a surveillance detection system and an insulation diffusion barrier, the lifespan of the network and its efficiency has been maximised as this allows for remote detection of any issues to provide a quick resolution.
The council has adopted Local Development Order 3 (LDO), which gives district heating permitted development rights over certain parcels of council and partner owned land, including all highways. Routing the pipework in LDO designated land therefore decreased the timescales of the scheme as planning permissions were not required using this route. To ensure the route was clear of any existing underground services, we completed ground radar and buried surveys which highlighted any areas to avoid, allowing us to design a pipework path that could be implemented as smoothly as possible without causing disruption to any third-party owned assets.
Collaborating with local planning consultants assisting in the progression of project planning
We worked closely with planning consultants, Turley, who are local to the area of Leeds and are experts in efficient planning of successful projects. They assisted in the smooth attainment of planning permissions, and organising engagement events with the local community. Due to the scheme being partially funded by the ERDF, we have to abide by specific timescales agreed with the funding body and it is therefore essential that we meet these goals throughout all the stages of the project. This meant that we had to design the scheme to allow for an efficient installation, with Turley assisting in meeting planning deadlines.
Engaging with residents to streamline the project design and installation
To assist the council in gaining support and buy-in for the project, we held multiple consultation days for residents which allowed them to ask questions and help with their understanding of the scheme. We also undertook individual surveys of each property to assess the layout and make sure the new internal heating systems would be compatible. This was beneficial as it would help with the efficiencies of the system installations and reduce the time required in each property to complete the work.