Heat-pump homes put less strain on grid than expected, study shows

Some of the first homes in the UK designed to meet new building standards put less pressure on the electricity grid than expected, a study has found. The all-electric properties in Handsworth, Birmingham, have heat pumps, which use electricity to provide heat rather than oil or gas. Researchers analysed the electricity consumption data over one year from seven homes on a 12-home social housing development called Project 80. The average peak electricity demand per property was “lower than we would expect”, said Dr Monica Mateo-Garcia, academic lead at Birmingham City University’s Centre for Future Homes. Completed in 2022, the Project 80 homes adhere to a 2019 draft version of the incoming future homes standard, which requires an 80% reduction in predicted carbon emissions for new-build homes in England compared with 2013 building regulations. The study was “a sterling bit of work”, said Richard Fitton, professor of energy performance at the University of Salford, who was not involved in the research. “We currently seem to be overpredicting how much power we need in new-build housing.” Critics of heat pumps have expressed concern that the devices could put excessive strain on the country’s electricity grid. However, in this case, the electrified homes used less energy at peak times than expected – and the timing of peak usage varied between properties. This, too, reduces stress on the grid. Annual total energy consumption for each property was between 40% and 67% lower than the UK average, which the researchers said was “a huge saving over the typical household”. The exact configurations of the seven dwellings varied, though most had air-source heat pumps for space heating and significant levels of insulation. All the properties had solar panel arrays on their roofs but no battery storage systems. Analysis of the homes’ carbon savings, not yet published, suggests there is still room to improve performance further, added Mateo-Garcia. Halfway through the year, the researchers realised that some residents were manually switching on their immersion heaters unnecessarily – seemingly unaware that their heating systems automatically provided hot water. In one case, a family had turned off their heat pump and were instead using electric fan heaters in a single room, which proved much less efficient than heating the whole house with the heat pump, Mateo-Garcia said. Generally, the social-housing occupants expressed delight at the quality of the properties compared with their previous dwellings. “They were really, really happy to be in those homes,” said Mateo-Garcia. “They said: ‘Oh, we haven’t seen any damp and mould.’” An interim report about the development published in 2023 revealed that one family, which had experienced a “recurring issue of asthma” in the past, had not experienced those symptoms since moving into one of the Project 80 homes. The study supports the rollout of heat pumps, argued Aaron Gillich, professor of building performance and policy at London South Bank University, who was not involved in the work. “We’re finding that all those reasons not to go ahead with a heat pump are slowly but surely falling away,” he said. Some of the homes analysed by Mateo-Garcia and colleagues had lower overall electricity consumption for space heating and hot water than expected, based on energy performance certificate (EPC) calculations. EPC ratings are notoriously poor at estimating the actual energy performance of properties. This finding highlights the need for realistic energy modelling for new homes, said Tony Hopkin, the head of construction, quality and innovation at Midland Heart, the housing association behind the development. He added that Midland Heart intended to explore options for storing energy at the development, for example with batteries. This could give occupants a greater ability to take advantage of smart tariffs, when electricity rates are lower at certain times of day. Midland Heart is in the planning process for a development of 95 homes that will adopt the principles of Project 80. A final version of the future homes standard legislation is yet to be published. The regulations will require all new homes in England to be fitted with solar panels and heat pumps from 2027 onwards. Fitton said the publication of the new future homes standard was understandably “a big task”, though he urged the government to follow through with it. “Let’s get this standard out,” he said.