The results of an independent trial that investigated the performance of hybrid heat systems have been unveiled by Worcester Bosch. The research project was undertaken by the University of Salford at the University’s Energy House Lab – a full-scale reconstruction of a pre-1920 end-terrace home commonly found across the UK, that could simulate different outdoor temperatures ranging from -3°C to 16°C. The aim of the trial was to demonstrate that hybrid systems – a gas combi boiler combined with a heat pump – could provide an efficient and carbon-saving solution for typical UK homes.

Based on the analysed data from the trial, a hybrid heat pump has the potential to:

  • Deliver a weighted average of 94% of the total annual heat demand from the heat pump element
  • See the heat pump handle 100% of the heating requirements when outdoor temperature is 7°C or above – and when at coldest (-3°C) contribute above 70% of the total space heating
  • Reduce 1,270kg of CO2 compared to a boiler-only saving – approximately 77% of the carbon savings of a full heat pump

The trial involved a ‘bivalent parallel system’ – where a heat pump and boiler run in parallel via a smart ‘hybrid manager’. The heat pump always acts as the primary heat source, with the boiler only adding supplementary heat to meet demand when the outdoor temperature drops, modulating to add just enough heat to meet the demand.

Worcester says that the trial confirms that a hybrid heat pump system offers real, practical benefits for homeowners, without the need for costly and disruptive preparatory work to their properties. Such a hybrid heat pump system would not require any changes to existing pipework or radiators.

The key benefits include:

  • Savings of £79 on annual energy bills compared to a standalone gas fired boiler
  • Improved Energy Performance Certificate (EPC) rating of the property from Band D to C
  • The provision of a more cost-effective route to lower carbon heating, delivering 1.5x the present carbon savings per pound of public spending

A push for policy change

The company believes the findings present strong evidence that hybrid heat systems should be considered in government initiatives that encourage increased uptake of lower-carbon technologies.

Carl Arntzen, CEO of Worcester Bosch, says: “Lowering the carbon emissions of the UK’s homes is a shared goal that requires a range of effective and accessible solutions. The findings from our work with the University of Salford are clear: bivalent parallel hybrid heat pumps are a practical and highly effective technology for the UK today.

“We believe government recognition and financial support for hybrid heat pumps, such as including this proven technology in the Boiler Upgrade Scheme (BUS), presents an opportunity to make the transition to lower carbon heating faster, fairer and more effective. It offers a practical and accessible stepping-stone on the journey to net zero for millions of households.”

For more information and to access the hybrid trial whitepaper, visit: https://www.worcester-bosch.co.uk/hybrid-heat-pumps-win