While heat pumps are seen as expensive, they can approach cost parity with gas boilers thanks to higher efficiency, said Jan Rosenow, European programme director at the Regulatory Assistance Project, to Professional Engineering – and as net zero goals draw closer, every opportunity to cut emissions must be taken.
Heating of buildings accounts for 23% of UK greenhouse gas emissions, according to government figures, and more than 85% of that is from gas boilers connected to the gas grid. That’s more emissions than from all the petrol and diesel cars on the road, said Rosenow, also an honorary research associate in energy and climate policy at Oxford University.
Declining rates of production from British gas fields and price volatility due to international conflict are other reasons for weaning off gas where possible, he added.
Heat pumps – which cost British Gas customers an average £5,690 to install, after the £7,500 government grant – can have similar running costs to gas boilers, even though electricity is roughly three-and-a-half to four-times more expensive than gas. This is possible because a gas boiler turns one unit of input energy (gas that is being burned) into about 0.8-0.9 units of heat, and the heat pump turns one unit of input energy from electricity, and external heat energy, into three or four units of heat.
“When you look back at the price ratio… you can see how you can get to a cost parity on the running costs pretty quickly,” Rosenow said.
Running a heat pump could be even cheaper than a gas boiler in some circumstances, he added. Relevant factors include local climate and housing stock – but the most important is efficiency, which he said largely depends on installation.
“If you have an installer who is very well qualified, very well trained, who also does… the heat survey and then the installation, the commissioning, the whole journey, and you get a really efficient system, that can really drive down your running costs,” he said.
Unfortunately however, that is not always the case. “We see a vast discrepancy between poor installs – which might just get you a coefficient of performance (which is the efficiency of the heat pump) of two, a really poor result – and really top ones, might get you up to five. So you're using, essentially, more than two-times less electricity to provide the same amount of heat.”
These poor installs can include using devices that are “significantly too large”, which causes an efficiency penalty. Conversely, if the radiators are too small and you have a high flow temperature (55ºC, for example), it could be less efficient than one with a lower temperature.
Issues could be avoided with better training for installation workers, Rosenow said. Technological improvements could also boost efficiency, including in the software that modulates the heat pump, and in the refrigerants and the compressors, but any gains are unlikely to have as significant an impact as better installations.
Consumer organisation Which? recently called on the government to introduce mandatory certification of heat pump installers to improve the quality of installations and reassure customers. Poor installations can also result in households being without heating or hot water for several days while issues are resolved, the body added.
“There is a major shortfall in the number of qualified installers available and this will need to be addressed by giving companies the confidence to invest in training,” the policy paper said. “Numbers are not the only issue, consumers will also need to be assured that installers have the appropriate qualifications and skills, and the right consumer protections are in place.”
Long-term solutions
Smart energy tariffs, which provide cheaper electricity for heat pump users, could be another important factor in reducing their costs, Rosenow said.
“The key is not so much lots of government support – that’s helpful, but I think the fundamental solution to resolving the issue around insufficient demand for heat pumps in order to meet the government's targets… [is] to really address the price ratio between gas and electricity,” he said.
“That's not an easy task, and government is already looking at that, but it would essentially mean that you have to either shift levies away from electricity onto gas bills.”
Levies from electricity bills could also be shifted into general taxation, he added, as Germany has done. “Or you have an exemption for heat pump electricity usage. That's what Denmark is doing, and you don't pay levies and taxes on that reduced rate.
“To me, it seems more important than adding more subsidies, having more support and just pouring more money into the upfront costs. Because I think long-term, it's not viable that every single person gets a government subsidy for heat pumps. Long-term, I think we will need to see a situation where finance models will arise similar to what we have already for when you purchase a car.”
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