Mass rollout of heat pumps presents opportunity for grid balancing and carbon reduction

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In the second in a series of three white papers on the subject of DSR for domestic heat pumps, Cambridge based smart energy specialist geo and heating manufacturer Vaillant have explored how the thermal properties of homes impact heat losses and how these factors ultimately influence the amount of DSR flexibility that heat pumps can offer. 

The UK Climate Change Committee’s 6th Carbon budget recommends that of the 28 million existing UK homes, 21 million should have heat pumps retrofitted to them. Many of these homes were built before building regulations mandated good levels of insulation.

The building regulations applied at the time the property was built, its level of insulation improvements and ventilation can lead to significantly different heat loss characteristics.

Our thermal simulations demonstrate that a 1970s built home, upgraded with more modern insulation, loses heat at a rate 3.5 times faster than a home built in the 2010s.

Our key findings highlight that when retrofitting heat pumps to older properties, the home should first be brought up to modern insulation standards, saving energy, reducing energy bills and reducing its carbon footprint. Better insulation and draught proofing benefit any home, regardless of how it is heated.

The existing UK grid infrastructure, including the Low Voltage (LV) substation transformers and feeder cables buried in roads and pavements that connect the power to the home, have until recently been largely designed for homes heated by oil or gas. Our modelling shows that if 10-20% of these fossil fuel heated homes were to switch to electrical heat pumps, then this will likely overload the local grid infrastructure at peak times. 

The cost and disruption to UK taxpayers to reinforce the local grid infrastructure can be minimised with some of the recommendations we propose.

Our analysis has looked to use some of the existing and new technology solutions to help alleviate the likely challenge that the mass rollout of heat pumps will bring. These include using a home energy management system coupled with DSR control protocols built into the heat pumps and the installation of larger buffer tanks or thermal storage. Alternatively, battery storage solutions or Vehicle-to-Grid (V2G) solutions may be needed in larger homes or older homes which lose heat more quickly.

Homes fitted with these solutions can then automatically use cheap renewable electricity at off-peak times, and store the energy later for the peak times, ensuring that the house occupants keep warm even during winter storm events which would otherwise further increase stress on the grid.

James Harrow, Chief Devices Officer at geo and one of the white paper’s authors, said “When we began our investigation into DSR flexibility of heat pumps and how this might help at the local grid level, we soon realised we had many findings worth sharing with government and industry colleagues both in the UK and internationally. If an industry consortium works together now we can begin to solve these problems which will otherwise hit us in the near future as heat pumps begin to be rolled out in increasing volumes over the next few years.”

Mark Wilkins Technologies and Training Director at Vaillant UK said “The thermal modelling exposed in this white paper highlights how important it is for UK homes to be better insulated, especially with higher fuel prices we are seeing at the moment. This is especially true if homes are to have heat pumps fitted in the future. In order to make homes flexible assets, heat pump installers need to consider adding more thermal storage or battery storage solutions based on the house type and age so that the home can stay warm whilst heat pumps can be turned down during peak times.