Heat (hot water and space heating) within buildings accounts for a significant amount of global carbon emissions annually. Fossil-based heating will need to be phased out to meet ambitious, but necessary, carbon reduction targets. This presents a major technical challenge for the building services and energy sectors to solve, how to quickly transition to sustainable and lower carbon heating solutions?

As electricity grids are decarbonising rapidly, emissions associated with electric fed heating systems are also falling and will continue to do so. As such, the electrification of heat, through heat pumps, is proven technology ready to deploy to enable the decarbonization of heat.

One challenge of the electrification of heat is that buildings within dense built environments (e.g. towns and city centers) are less suited for individual heat pumps (either air-source or ground-source) due to the lack of external space (e.g., rooftops) and the high operating temperatures of existing buildings.

One solution for dense built environments is the use of district heating systems. District heating systems allow for the diversification of demand and centralisation of heat generation assets. Therefore, connecting to a district heating network removes the space requirement and reduces capital costs for buildings to decarbonise.

This presentation aims to outline how a hybrid heat pump led district heating system allows for the heat pump size to be minimised, reducing footprint required and capital cost, whilst still providing the majority of annual heat demand and thus carbon reductions. The heat pump can be supplemented with peaking plant, such as gas or electric boilers, for use during periods of high heat demand.

A case study of the design of a 30MW district heating system with 7.5MW of heat pump to generate 85% of annual heat demand will be presented to demonstrate the benefits of a hybrid heat pump lead district heating system.


Lucy is a Consulting Engineer with 2-3 years of experience in heat networks and district heating systems. Lucy joined the industry in 2019 after graduating with a master’s degree in Chemical Engineering. Lucy’s role involves working on the detailed design, installation, and commissioning of heat networks, to deliver cost and energy saving improvements. Lucy is a committee member of CIBSE YEPG, actively participates STEM outreach, and CIBSE ASHRAE Graduate of the Year 2021.