Jarrad Bedford, Head of Sales – O&M at Insite Energy, examines the rise of heat pumps in district heating.
The UK’s commitment to achieving net zero by 2050 is transforming the way we heat and cool our homes and workplaces. With the built environment responsible for a quarter of the nation’s greenhouse gas emissions, decarbonising HVAC technology is an important and urgent priority.
Driven by national and regional government policy, heat networks are increasingly seen as a scalable, low-carbon solution that can efficiently serve multiple buildings from a single heat source. Zones are being designated in London, Leeds, Plymouth, Bristol, Stockport, and Sheffield within which new housing developments and certain other types of buildings are required to connect to a heat network. Construction is expected to start in 2026, backed by a £5.8 million government investment.
From boilers to heat pumps
Concurrent with this roll-out, a shift is taking place in the types of heat sources powering these large-scale heating and cooling networks. While they have historically tended to use large gas, oil or biomass boilers, heat pumps are now playing an increasingly important role. Combining heat networks with renewable power sources in this way, promises to supercharge carbon-reduction efforts.
This is particularly true in cities like London where especially stringent low-carbon policies prioritise both heat networks and heat pumps. Projects within Greater London must adhere to the London Plan, a crucial piece of legislation aiming to ensure that 25% of the capital’s heat and power is generated through localised decentralised energy systems by the end of this year. The Plan aligns with, and in some cases, exceeds the requirements of the government’s Future Homes Standard, which will ban natural gas boilers in new homes in 2027.
Not only do heat pumps repurpose renewable ambient heat from the ground, water or air, but they use thermal stores to retain energy until it’s needed, such as morning and evening peak demand times. Consequently, heat pumps have a significant advantage over gas boilers when it comes to obtaining the high-scoring energy performance certificate (EPC) ratings that city planning authorities now require.
Although the use of heat pumps in heat networks still remains relatively rare, it’s changing fast. The majority of new heat networks under development now incorporate heat pumps.
Air source is by far the most popular choice of system because ground source heat pumps require large land excavations which are generally problematic and disruptive in urban environments. However, heat pumps can be designed to repurpose waste heat from a variety of sources such as rivers, sewers, the London Underground, data centres or even supermarket fridges.
Live example
A compelling illustration of this trend towards air source heat pumps (ASHPs) in heat networks can be seen at a new 244-unit development in Barnet, North London.
A four-building residential project, it’s part of a heat network powered by 12 42 kilowatt (kW) ASHPs. Together, these are estimated to be three times more efficient than the same heat network running gas boilers. It’s a great example of a future-proofed, low-carbon development that will see emissions drop further as the proportion of the UK’s electricity supply coming from renewable sources increases over time.
Ambient loops – simplifying retrofits
One exciting technological development of particular relevance to refurbishment projects is the use of ambient loops. Instead of using a centralised heat source to distribute high-temperature water around a heat network, an ambient loop circulates water at lower temperatures – typically between 10°C and 30°C. Individual ASHPs in each dwelling then upgrade this low-level heat to meet space heating and hot water needs.
Known as fifth generation heat networks, the ambient loop approach reduces heat losses across the network without the need for highly insulated pipes, thereby increasing efficiency and reducing costs.
It also offers flexibility for refurbishment projects because existing internal risers and pipework can often be used, minimising cost and disruption. New properties can be connected to the circuit at limited cost, too, often without the need to increase the capacity of a centralised heat source, ensuring scalability. And, where outdoor space is limited, ASHP units can often come integrated with hot water cylinders
Metering
Ambient loops do introduce additional regulatory considerations, however. When the government’s new Heat Network Technical Assurance Scheme launches next year, it will introduce performance-based technical and service standards across the entire heat network lifecycle, from design through to installation, maintenance, and metering.
This will almost certainly include ambient loops. Smart meters will become a requirement and will need to be retrofitted if not already present. That may mean additional planning around space, accessibility, and data infrastructure.
Widening skills gap
While beneficial for the environment, all these rapid technological changes also demand new skill sets from heating professionals within a timeframe that is proving too short for the market to meet demand. For engineers who have been trained to install and maintain household gas boilers, switching to much larger, interconnected, low temperature systems is not an easy feat. Specialised training is certainly needed.
Apprenticeships such as the Level 3 Low Carbon Heating Technician and Level 4 Building Services Technician are beginning to address this problematic skills gap. Although they generally take three years to complete, we offer a fast-track route to our own experienced engineers in order to speed up an injection of expertise and talent into the workforce. But unless similar training and accreditation schemes are scaled up across the industry, shortages could not only slow the pace of heat pump adoption in refurbishment projects but decelerate the country’s overall transition to renewables.
Looking ahead
For refurbishment projects, the move towards heat pump powered heat networks – particularly those using ambient loop designs – represents a practical pathway to decarbonisation. While challenges remain around cost, skills, and regulation, the trajectory is clear: heat networks will increasingly depend on ASHPs and innovative low-carbon energy sources.
With careful planning, including the integration of mandatory heat metering, refurbishment schemes can achieve regulatory compliance while offering residents lower-carbon, future-proof heating.
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