As we kick-start the annual Clean Air Day, we wanted highlight exactly how heat networks play an important role in making everyday a clean air day. The past few years district heating has been placed under the spotlight as an answer to upgrading our city space to becoming zero carbon. But how is this possible?

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 progressing 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.

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 environmental benefits

An example of environmental benefits is Leicester’s City Centre District Heating Scheme, which spans six estates in the city and will have saved more than 20,000 tonnes of carbon by 2020.

The swap shop for fuels

District heating and communal heat also means that different fuels can be used in ways that just wouldn’t work in traditional utilities. Various combinations of energy sources can be used on district heating schemes, including traditional gas fired boilers, biomass, CHP and low grade heat technologies such as ground source heat pumps.

Furthermore, heat that would otherwise be wasted during industrial processes can be used when the plant is connected to a district heat network.

An example of this would be Leeds City Council’s Recycling and Energy Recovery Facility (RERF). The plant collects 306,000 tonnes of waste recycling 40% to generate enough power for 22,000 homes. By 2019 the plant will provide heat and hot water to 2,000 Council homes across Leeds.

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. 

Key takeaways

• Clean Air Day, an annual event, takes place in June, it highlights the real concern of CO2 emissions and how we should be driving to make a difference
• 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, with guidance including the CIBSE CP1 Code of Practice addressing this