UK Local heat networks - reducing reliance on gas and de-carbonising heating

Electrically operated heat pumps operate by circulating a refrigerant which picks up small amounts of residual heat from the surrounding environment which is then pressurised, concentrating and allowing the heat to be released. The released heat is typically used to heat water which can be circulated through a wet heating system such as radiators or underfloor pipework. The pressure is then released and the refrigerant re-circulates picking up more heat. Heat pumps fall into two broad categories dependent upon their source of heat extraction being either from the air or from a ground source usually accessed using buried coils, boreholes or even from lakes, canals and ponds. A number of systems can also be operated as a reverse cycle chiller to provide cooling in times of warm weather. For optimum results the property in question needs to be appropriately insulated. 

The energy coefficient of performance for the electricity powering the pump is often in the region of 300% to 400% ie, it gives out 3 to 4 units of heat for every unit of electricity it uses. Gas boilers by comparison are unlikely to exceed 90% efficiency however a true cost comparison needs to factor in the differential costs of gas and electricity.

De-carbonising heating can therefore be supported by both the replacement of gas boilers with heat pumps and as the UK has removed all coal from power generation and moves towards more renewable generation, the source of the electricity becomes ever greener as well. Our recent feature on rooftop solar projects also set out the benefits of localised electricity generation and uses for surplus supply. 

Over recent years the government has supported the installation of heat pumps through the non-domestic Renewable Heat Incentive which provided incentives for the installation of 55GWh of renewable heat technologies before its closure in March 2021 and the installation of clean heat measures through the Public Sector Decarbonisation Scheme. Phases 1 and 2 of this scheme offered over £1 billion in grant funding to publicly owned buildings for heat decarbonisation and energy efficiency projects. Phase 3 may fund further projects with a total budget of £1.8 billion. Following its launch in 2022, the Boiler Upgrade Scheme also provides capital grants, including to business premises, with a total budget of £450 million over 3 years. According to The Non-Domestic National Energy Efficiency Data-Framework 2020 (England and Wales) at the end of March 2020 there were over 1.65 million non-domestic buildings in England and Wales so the transition represents a significant opportunity.

Focusing on ground source heat extraction, the main hurdles for adoption are proving to be ground space for the coils or boreholes and the cost. Typically the ground infrastructure is connected to only one property however we are starting to see developers consider larger scale ground works with a view to connecting several properties to a single heat source. With the advantages not only of the economic scale but also for the performance of heat extraction whilst minimising ground disruption, these larger scale ground source systems, known as local heat networks, are starting to become viable options. In densely populated areas, local heat networks may prove to be the low cost low carbon heating option with the capability of being adapted to use sources of heat from industry, data-centres, rivers and canals, or geothermal energy in order to decarbonise towns and cities whilst securing the UK’s energy independence.