With around 14% of carbon emissions in the UK driven by the usage of fossil fuels for home heating, cutting this back dramatically – in line with the UK target of achieving Net Zero by 2050 – is a key government objective. Several technologies play a role in decarbonising the heat sector, points out the Department for Business, Energy and Industrial Strategy (BEIS) – with heat pumps generally considered to be “the future of heating”, being powered by low-emissions electricity, not fossil fuel boilers. While many homeowners are not yet looking to have a heat pump installed the retrofit market represents a huge opportunity in the longer term.
And while the government’s Boiler Upgrade Scheme grant to help households with the costs of the switchover has now been increased by 50% – from £5,000 to £7,500 – there are still big questions to be addressed along the way, such as: what enabling works might be required, such as additional insulation, double glazing or larger radiators? And: is the supply chain sufficiently mature to deliver and support the huge increase in domestic heat pumps the switchover demands?
On the first point, while heat pumps can be applied to all building types, they are not a like-for-like replacement for gas boilers and electric heating systems – and careful and detailed system design is required to ensure they will work efficiently and effectively. Another key challenge for penetrating the sector is that, whereas a failed boiler usually requires an immediate replacement, heat pump installations tend to demand more time, as well as a number of ancillary changes (such as replacing radiators and control systems) and often improved insulation. Additional costs might include buffer tanks, hot water tanks, heat emitters, piping and valves, as well as non-equipment costs, such as design, commissioning, distribution and overheads.
“The time required to physically install an ATW heat pump may only be around one to three days [compared with one day for a boiler], but the time required for designing and planning the installation is often more extensive, although highly variable,” says the BIES. “Consequently, installing a heat pump tends to be much more involved than simply replacing a boiler.”
CARBON COSTS
As the Carbon Trust also points out: “A key difference between heat pumps and traditional forms of heating is that they operate most efficiently at lower flow temperatures. Some energy-efficient buildings can already accommodate lower temperature heat and many heat pumps are capable of delivering higher temperature heat. However, optimising performance… will often require upgrading the heat emitters and reducing heat loss through the thermal fabric of the building.”
What about the running costs involved once a heat pump has been installed? Unless particular attention is paid to ensuring maximum efficiency of the heat pump in the heating system – by using best-practice radiator/underfloor heating design – heat pumps are likely to be slightly more expensive to run, at least initially, adds the Carbon Trust. “However, as utility prices fluctuate over time… we expect that heat pumps will become the cheapest, as well as the lowest, carbon form of heating available.”
Then there’s the matter of who is best suited to carry out the installations. According to the trust, MCS certified installers (MCS being the industry-led quality assurance scheme) should be used to ensure that best practice in heat pump design, installation and commissioning is observed for domestic and smaller-scale projects. However, with a forecast that 33,700 trained installers will be needed to meet the government’s ambition of 600,000 heat pumps being installed annually by 2028, is this achievable?
Charlotte Lee, CEO of The Heat Pump Association, believes it is. “Our manufacturing members alone have the capacity to train up to 40,000 installers a year. With the right policy enablers to stimulate demand for training among installers and an increase in consumer demand for heat pumps, we are confident the necessary skill base can be developed in time.”
Lee also argues that a good deal of ‘myth busting’ needs to take place, including around “misinformed claims that they [heat pumps] are only suitable in highly insulated buildings, that they do not work in older buildings or that expensive measures need to be taken that are unnecessary, if we just carry on with fossil fuel heating”.
None of these is true, says Lee. “If a heat pump heating system is designed, sized and installed correctly, so its heat distribution system [in homes, most frequently radiators or underfloor heating] can provide the necessary heat at lower temperatures, the heat pump will perform optimally.”
One other possible obstacle to achieving high-volume retrofitting is that there are currently not enough heat pumps manufactured in the UK to support a localised supply chain. The majority of heat pump components (the Tier 2 supply chain) used in UK heat pump manufacturing (Tier 1) are currently imported, with a significant proportion from outside Europe. However, adds the BIES, if UK-based heat pump manufacturing increased, establishing component manufacturing in the UK would be achievable. “This effect is already documented among those manufacturers which do have an established presence in the UK, where the proportion of components sourced locally has increased significantly with growing demand, as local businesses develop capacity.”
HEAT PUMP TRIAL EXTENDED
Meanwhile, following a successful pilot, National Grid’s EQUINOX (Equitable Novel Flexibility Exchange) grid flexibility heat pump trial has been renewed for a second term. The first trial saw 400 heat pump customers across the UK participating in the ‘turn down’ scheme, whereby they adjusted heat pump use to reduce peak electricity demand. According to National Grid, the initial pilot provided a total measurable household reduction of 10.8MWh – equivalent to the energy needed to make more than 300,000 cups of tea. The project began in December 2022 and is now planned to run until December 2025.
“As thousands more homes switch to heat pumps, flexible systems like this are going to be even more crucial to balance demand at key times,” believes Matt Watson, head of commercial and operability at National Grid DSO. “Trials such as EQUINOX [run by National Grid Electricity Distribution] show that customers are willing to tweak their everyday lives to save money and help balance the system.”