Using System Data to Understand the Performance of Multi-Occupancy and Commercial Ground Source Heat Pumps in the UK

With heating accounting for 23% of the UK’s emissions in 2019, decarbonising this sector is vital to achieve net zero by 2050, as legislated in the UK. Ground source heat pumps will be a key technology in realising this, though little data is available on their long-term performance in the UK, particularly commercial and multi-family systems. Extracting the learning from heat pumps currently in operation will be crucial to inform the systems being installed at present, helping them reach higher overall efficiencies. This thesis provides insight on three different case studies, each with more than one year of operational data. This includes a system using geothermal foundations, two buildings utilising shared ground heat exchangers, and an open loop well doublet system. The systems generally perform at comparable efficiencies to those in the literature, both in the UK and overseas, but improvements are possible. The control of the ground loop in the first case study appears sub-optimal, with heat primarily extracted from the boreholes and rejected to the energy piles. This negates the potential of the ground as an inter-seasonal energy store. Case study two investigates the long-term data on the diversity within shared ground heat exchangers for the first time, showing low utilisation in all arrays except one. In particular, the contrast between two theoretically similar arrays demonstrates the difficulty in accounting for user behaviour. Case study three has the highest efficiencies but shows large periods of unnecessary operation. These studies highlight end users as the greatest factor on system performance, stressing the need for simple yet thorough guidance. They also demonstrate the need for at least a basic level of continual monitoring to ensure optimal usage patterns, controls, and maintenance regimes. Such understanding and monitoring must be carried across changes of ownership to ensure efficiencies are maintained.