Heating our homes and businesses causes almost a third of UK emissions, yet carbon reduction policy has traditionally centred on power supply. Excellent progress has been made in decarbonising the UK's power supply in recent years, with a huge shift to renewable energy sources. Now the focus is rightly moving to heat.

Renewable heat

Heat network expansion is crucial to the decarbonisation of heat and it is among the policies included in the government's Clean Growth Strategy, published last year. This sets out plans to deliver on the UK's CO₂ reduction targets.  

As a follow-up, an open consultation was launched in March 2018 on 'A future framework for heat in buildings', which examines how to move towards cleaner heating in the UK.

The role of district and community heating

Decentralised district and community heating systems have an important part to play in providing greener, more affordable and secure energy supplies. It stands to reason that a central boiler plant is far more efficient than many individual boilers. Such economy of scale can deliver typical energy savings of 25% compared to lots of gas boilers in individual buildings. This can also generate savings of up to 50% compared to electric heating.

The UK district heating sector has suffered from an image problem in recent decades, largely due to problems with early post-war coal-fuelled projects, which were poorly maintained.  But the district heating movement is now moving forward at some pace. UK urban councils are helping to drive the expansion of heat networks. There is both a London Energy Plan and a national ambition to make much more use of such schemes.

The government's £320m Heat Network Investment Project is one example of this commitment to the growth of district and community heating.

The Scandinavian exemplar

Although expansion is afoot and 1,750 heat networks already exist across the UK, this is a tiny proportion of what is possible. Contrast this with Scandinavia, which sets an example for others to follow. In Danish towns and cities, 55% of homes and up to 95% of buildings are served by heat networks. 98% of networks are supplied by renewable fuels, with far higher efficiency and satisfaction rates than seen in the UK to date.  In Sweden, cities such as Stockholm and Malmo supply more than 90% of their heat via heat networks.

Embracing renewable energy

Heat networks offer an excellent opportunity to use low carbon and renewable technologies, which can make a big contribution to pollution reduction within densely populated towns and cities.

Carbon emissions can be minimised by switching fuel sources to biogas CHP, high efficiency heat pumps, large scale out-of-town biomass, or to waste heat schemes.  

UK best practice

In London, plans are being implemented to use heat from the London Underground and other sources. Elsewhere, Sheffield City Council has switched its plant rooms from gas boilers to plate heat exchangers that are fed by district mains. These are connected to a clean burning recycling facility, which consumes the city’s non-recyclable waste: producing 60 MW of heat and 20MW of electricity.    

Other future looking UK heat networks include the Gateshead District Energy scheme, which supplies heat and power to domestic, public and commercial customers from 4MW gas-fired CHP engines via a new three kilometre heat and private wire network.

Leeds City Council is developing a heat network that will be use heat from processed waste produced by the Council's recycling and energy recovery facility. This huge heat network is planned to cover a 6km across the city and serve 2,000 homes.

Fife Council's Glenrothes heat project seeks to harness heat from a local biomass plant to serve public buildings, commercial and industrial premises, and homes. This network would be capable of future expansion.  

In London, Enfield Council's Lee Valley Heat Network will provide combined heat and power to 30,000 homes and businesses and is projected  to cut the carbon footprint of homes connected to the network by 80 per cent, compared to households with conventional heating.

This project ties together a series of heat networks that are in regeneration across the Borough of Enfield. These include, Meridian Water, Arnos Grove and Ponders End heat networks. Energetik, Enfield Council’s local energy company, has selected Switch2 Energy to provide customer support and smart metering for its low carbon community heat networks

Design and development of heat networks

There have been many mistakes made in past heat network design and implementation, which we must learn from. It is important that district and community heating schemes are sized accurately to meet actual demand, rather than to satisfy planning regulations and meet compliance requirements.

Future maintenance requirements and costs must also be at the forefront of design decisions.  Developers should review future operational efficiency, including factors such as low heat loss, flow rates and return temperatures.

Another key consideration is to design in flexibility to accommodate future expansion and the use of new lower carbon and renewable technologies. This will reduce whole life operation costs, as well as reducing greenhouse gas emissions. It is also important to follow best practice, such as The CIBSE/ADE Heat Networks: Code of Practice and guidelines set by The Heat Trust.

It is also important to achieve compliance with Heat Network (Metering and Billing) Regulations 2014 and use smart metering solutions, such as next generation pay-as-you-go energy meters.

Above all, heat network design must be customer focused and place residents' needs at the centre of decision making.

Key takeaways

• Community and district heating plays an important role in providing greener, more affordable energy supplies
• There are many Government initiatives that support the growth of heat networks 
• Many Core Cities in the UK have planned large district heat networks across their cities to serve renewable energy supplies to both commercial and residential buildings
• There is still a lot to learn in the design of heat networks