See our 'About us' page for information on the project, and to learn more about the team.

A district heat network refers to a heating system which uses a common heat source (or sources) for use by multiple users. Like a traditional boiler supplies heat for your home, a heat network uses a central plant to capture the heat, and then a network of pipes around the community to distribute the heat to buildings. You can think of the heat network as central heating system for the whole community. The energy plant acts as a ‘boiler’, and the distribution network of pipes delivers heat to each connected building in the community, like if each building were a room in a house. You are in control of your individual home’s heating, just like you can control individual radiators in a house.

There are many potential sources of heat for use in a low-carbon district heat network, but they can be broadly categorised into the two types below. Historically, heat networks have regularly been developed to use gas as a heat source, however these types of networks are being phased out for zero-carbon alternatives.

- Renewable sources of heat. This refers to heat that can be sourced from ‘untapped’ renewable sources in the natural world. For example, capturing latent heat from a waterway, such as a river or lake.

- Waste sources of heat. This refers to heat that can be captured from existing industrial processes that would otherwise be wasted. An example of this would be capturing and using heat caused as a by-product of incinerating rubbish.

As there are no large sources of ‘waste heat’ near to Kings Langley, this feasibility study is focusing on using the first type of heat: heat that can be captured from ambient, renewable sources.

There are still a number of ways a network like this could work, but generally, a ‘heat exchanger’ captures heat from near the source and transfers this heat into the insulated pipes around the network. In the example of capturing heat from a waterway, water would be extracted to the nearby energy plant where the heat would be transferred to the network. The water would then be returned to the waterway, at a slightly cooler temperature. The water only interacts with the network at the heat exchanger, so there is no risk of water becoming polluted, or vice versa.

Once the heat is within the network, it is distributed from the energy plant to individual buildings via the network of insulated pipes. This can include domestic, commercial, and public buildings.

Zero carbon

District heating is playing a vital role in the clean energy transition, and the move away from heating our homes with gas. Currently in the UK, heat networks reduce carbon emissions in buildings by around 1 million tons of CO2 each year, as opposed to if the buildings were heated in traditional ways. This equates to 3,065GWh of gas per year not being burned, enough to heat 216,000 homes. It is estimated that by 2030, as more heat networks are established, that 5.7 million tonnes of CO2 will be saved per year in the UK.

Affordable

District heating networks are competitive in terms of pricing with individual heating. They are not fundamentally cheaper to run than a gas boiler, but importantly, the renewable heat sources used within a district heat network allow for long-term price stability. Customers of a heat network are not at the liberty of a volatile gas market, so are not at risk of price hikes in their heating bills.

A range of funding options are available to install the heat network, in order to minimise up-front costs to those wishing to connect to the network

Community-led

Developing a district heat network provide can empower a community to make decisions on how their homes are heated, and how the network will operate. A range of governance and ownership options exist for district heat networks. The choice will depend on what is most suitable within the context of a specific community. Options can include co-operatives or local government ownership of the heat network.