The HyCompact project built on learnings from the FREEDOM project to explore the potential role for compact hybrid heat pumps in decarbonising domestic heating. A compact hybrid has a heat pump contained within the boiler unit, which is wall hanging and only slightly larger than a standard boiler-only unit. The project was led by Wales & West Utilities, with Passiv, UK Power Networks, Imperial College and Delta-EE as project partners.
The project sought to understand customer acceptance of compact hybrid heat pumps. Compact hybrids require only a single indoor unit and can be installed in properties where there may not be space for a standalone heat pump outside. They are simpler and quicker to install and can be installed by Gas Safe Registered engineers, overcoming the huge skills challenge for heat pumps.
As part of the HyCompact project, Passiv installed seven SIME compact hybrid heat pumps into domestic properties.
Passiv used its Smart Energy Platform and hybrid heat pump controls to optimise the performance of the heating systems. The Platform created a thermal model of each home the compact hybrids were installed in and used local weather forecasts and external temperature estimates to maximise the heat pump’s efficiency and reduce energy bills. The Platform switched between the two heat sources to automatically use the most cost-effective heating mode at any time of the day or night.
HyCompact showed that compact hybrids could make a significant contribution to decarbonising the UK’s heating. The compact hybrids installed as part of the trial used the heat pump between 40% and 58% of time. This resulted in carbon emissions that were up to 50% lower than a standard gas boiler - an annual reduction of over 1 tonne of CO2 per home. The project showed that compact hybrids had running costs that were comparable to a conventional gas boiler. However, running costs could be reduced if optimised according to a time of use tariff with the Passiv Smart Energy Platform.
HyCompact demonstrated that a compact hybrid with smart controls can flexibly switch between fuel sources based on external signals. These included network stress indicators, and in the future, could include periods of varying hydrogen production. Analysis conducted by Imperial College London as part of the project showed each compact hybrid heat pump installation could deliver energy system cost savings of £100 per year.
Analysis of UK housing archetypes conducted for the HyCompact project revealed that 14 million UK homes could be suitable for a compact hybrid based on space constraints and annual heating demand.