The UK is committed to become a low-carbon economy, with a reduction in greenhouse gas emissions to net zero by 2050. To do this will require fuel switching, for example from fossil fuel power to renewable energy sources. In the UK the main source of emissions from the residential and public sector in 2018 was the use of natural gas for heating. Due to the diversity of heat demand by consumers, which varies with time/season and in magnitude, no single approach will provide the optimum solution. Geothermal heat has been widely recognised to have the potential to make significant regional contributions to decarbonising heating in the UK, but currently deep geothermal and heat pumps account for just 5.2% of renewable energy sources. This project will investigate the use of closed loop single well geothermal systems as a viable alternative in scenarios where traditional open loop geothermal systems are not feasible. It particularly addresses the possibility of using wells drilled for other purposes, that might have failed in their original objectives, as sources of geothermal energy, thus mitigating some of the costs of their construction. Uniquely, the research will use, in Newcastle city centre, an existing 1.6km deep borehole and adjacent large instrumented building as a research facility, and integrate the research as part of whole energy system approach. Modelling will couple the heating/cooling needs of new urban buildings with an understanding of the performance of a single well geothermal system so that those demands are met. The project will address fundamental challenges in 1) heat abstraction and storage; 2) the engineering challenges of integrating geothermal energy to whole energy systems, and 3) regulatory and legal implications of closed loop systems and subsequent liabilities. The proposed research sets out to mitigate the technical and economic risks associated with deep UK geothermal energy for heating and cooling, and so to facilitate its future adoption to enable zero carbon targets to be reached.