A group of researchers from the University of Southampton in the United Kingdom and UK energy company Good Energy has investigated how third-party control of air-source heat pumps (ASHPs) could enhance the energy flexibility of providers through peak-shaving strategies. The study found that ASHPs can deliver a significant average power reduction during periods of high demand.
The field trial involved 30 test buildings and 30 control buildings in southern England. In the proposed system configuration, a central control system managed the ASHPs during peak grid demand periods.
Testing began in January 2023 and continued through March 2023. Across the participant pool, the mean floor area was 141 m², considerably larger than the UK average. Around 33% of the homes were built before 1945, 13% after 2002, with detached properties being the most common. Participants were generally affluent, highly educated, and predominantly homeowners aged 30–64.
The system’s performance was evaluated through three types of energy flexibility events: a “power limitation” scenario, in which heat pump power was reduced to 60% of full capacity; a “call to heat” scenario, in which space heating was turned off; and a “call to heat – DHW off” scenario, in which both space heating and domestic hot water (DHW) were turned off.
A maximum of one event occurred per day, and participants were informed that events could take place between 16:00 and 21:00. They were able to override third-party control at any time via a dedicated webpage.
During testing, 22 flexibility events were initiated, lasting between 30 minutes and 2 h. Third-party control override requests accounted for 1.1% of total potential requests during events, 1.3% after the event on the same day, and 0.3% before the event, slightly higher than the 0.7% recorded on non-event days. Longer, two-hour events saw 4.4% override requests, while shorter events had lower rates.
The field trial showed that the “call to heat” and “call to heat – DHW off” mechanisms achieved a substantially greater power reduction compared with “power limitation,” with an average reduction of 88.2% and a maximum demand reduction of 1.581 kW.
“However, the data also revealed evidence of a substantial rebound in heating power after energy flexibility events—often referred to as the ‘snapback’ effect,” the researchers explained. “This can be mitigated by combining the two mechanisms in sequence: first ‘call to heat,’ then ‘power limitation.’ This approach was tested in the 20th event on 22 March 2023.”
Their findings are available in “Embedding energy flexibility capability in air source heat pumps via third-party control: Insights from a field trial on residential buildings in England,” published in Applied Energy.
The research team also plans to explore how smart systems could be integrated with other low-carbon technologies, such as solar panels and home batteries.
“Most people just want their homes to be warm and their bills to be affordable,” said lead researcher Patrick James. “Our study shows that heat pumps can provide comfortable heating while helping the grid cope at busy times. With smart control, they can play a key role in cutting emissions and making our energy system more resilient – and even save some money on their bills.”
“This research shows how new technologies like smart heat pumps can benefit both people and the planet,” said Kedar Pandya, the Executive Director for Strategy at the UK Research and Innovation Engineering and Physical Sciences Research Council (UKRI EPSRC), which funded the project. “By reducing peak demand, households can help prevent blackouts, lower costs, and reduce emissions, all while staying warm.”
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