Performance investigation of a novel low-carbon solar-assisted multi-source heat pump heating system demonstrated in a public building in Hull

• A first-of-its-kind copper tube solar collector array is reported and tested. • A novel heat pump is demonstrated for the first time in an operational environment. • The solar heat pump efficiency ranged from 2.12 to 2.68 at high water temperature. • The solar heat pump reduced carbon emissions by 63.69 % with a bill saving of 0.73 %. • The system successfully met the space heating demand by replacing gas boilers . Global climate change has raised great attention from governments and prompted a wave of application of low-carbon heating technologies. However, solar-assisted heat pump, as an attractive technology, has challenges of unstable performance and complex structure and control strategy in practical application. Following the carbon-neutral strategy, a novel low-carbon solar-assisted multi-source heat pump heating system (LSMHS) is therefore proposed to improve the application potential of SAHP, which is demonstrated in Hull Central Library by replacing the library's original gas boiler heating system (GBHS). The LSMHS integrates eight novel multi-throughout-flowing solar collector arrays with an innovative two-stage heat recovery heat pump which can automatically switch different operation modes according to weather conditions. The practical operation results revealed that the LSMHS maximized the advantages of each component and achieved a high monthly average system COP sys ranging from 2.12 to 2.68 in the three-month demonstration. Eventually, the LSMHS provided a bill saving of 0.73 % with a significant carbon reduction of 63.69 % when compared to the GBHS in practice, achieving an equivalent bill saving of £6.7 for every tone of carbon reduction. The remarkable demonstration results showcased the application potential of the novel LSMHS and gave valuable guidance for low-carbon building heating.