How Do District Heating Systems Work?

In this article the energy management and closed water system specialists at Water Treatment Services take a look at the growing popularity in district heating systems, explaining what they are, how they work, and their advantages and disadvantages.

What is district heating?

Before we can go into detail about district heating, we must first understand what it is. An alternative, and some would say more understandable name for it is network heating.

Network or district heating describes a larger scale heat transfer system that relies on one centralised heat source to provide a supply of hot water and heating, via underground pipework connected to multiple properties or units. The residents of these units – usually flats, houses, apartments or other buildings – use the energy generated by the central source to heat their homes and supply hot water.

Is district heating the same as central heating?

No – central heating typically uses gas to heat the home. Other versions of central heating use electricity, solid fuels or oil. With district heating, there are other options as well, many of which are far greener than traditional sources of fuel. Examples include solar energy and geothermal energy.

How does district heating work?

District heating systems rely on a large, centralised heat generator connected to a network of pipes which distribute the heat, usually via hot water supplies to each building connected to the network. These pipes typically run underground and extend to reach individual heat interface units in each property (homes, offices and other buildings). These units (known as HIUs) deliver hot water and heat the buildings as desired by the building occupants.

What are the advantages of district heating?

District heating systems are typically more energy efficient than having a separate heating systems installed in individual properties. Imagine a series of new build homes where a network of heating pipes is laid before the properties are built. It will not be left to each resident to provide heating to their own home. Instead, each property is already connected to the central heat generating plant which provides the hot water that runs through the underground pipes to each property.

There’s also the prospect of resorting to renewable energy sources on a large scale to provide energy to power the network. Instead of having a gas boiler restricted to gas or electric heaters, a district heating network can be powered by heat pumps, solar panels, biomass boilers, and numerous other eco-friendly sources. This benefit in turn means a district heating system generates fewer emissions, as it can use renewable energy sources to operate.

Further advantages for residents and building users

For those living or working inside properties where the heating and hot water are supplied by this type of network system, the most notable benefit is convenience. This is seen in several ways. For starters, there’s no need for a large boiler or hot water tank to be situated anywhere in the property, freeing up valuable space. Yes, there will be an HIU instead, but many are a lot smaller than the average boiler, and as technology gets better, sizes are getting smaller all the time.

Those using the properties will also recognise they are using one of the most modern and eco-friendly methods for heating their homes and workspaces and providing a source of hot water – and today, that counts for a lot.

What are the disadvantages of district heating?

From the information provided here thus far, you can likely tell what the main disadvantage of district heating could be. For the system to work, there must be a network of pipes underground that are properly insulated to make sure the water flowing through them stays hot enough and wastes less energy.

If a new high rise block of flats is being planned, district heating can be accounted for at this stage and the pipes installed underground before the rest of the building process begins. The same applies if a series of new houses or office units was planned by a property developer, who could put in place the pipework prior to the remainder of building.

With existing housing stock, this cannot be done. Extensive research and mapping of existing underground services (water, electricity, gas, broadband, drainage etc.) would need to be undertaken to see whether it would be possible to add the required network of distribution pipes to make such a system available. Moreover, with many properties privately owned, it would be left to the individual home or business owners to decide whether they wanted to connect to it or not. Apartment blocks are cheaper to connect to the system than houses for this among other reasons.

What percentage of the UK uses district heating systems?

As of 2021, only around 2% of homes across the UK are connected to this type of heating network. One source estimated that approximately 50% of UK homes could potentially be connected to a district heating system, since not all properties would be suitable. For instance, rural properties that are in the middle of nowhere would not prove cost effective to connect in this manner, in much the same way they couldn’t be connected to the gas network.

Using centralised heating systems in other buildings

Compared to the history of other heating methods in the UK, district heating is still in its infancy. However, given that it works best in apartment buildings, it is perhaps not surprising that it can also work well in other large buildings or multi-property estates.

Typical examples would include an office or industrial park where several commercial buildings with different units are let to different tenants. Office buildings could also use the system if it was installed prior to construction.

What is the future for district heating?

It’s clear that installing a district heating system as part of the early stage construction process of a building or series of buildings is by far the easiest method of installation.

At present, there are ten times as many homes compared to businesses that are connected to this type of network heating system. Furthermore, as we become more aware of district heating, there are likely to be more schemes that use it. That said, retrofitting older buildings to connect to such a network is unlikely to happen – at least not until costs come down.

While the installer of the system will most likely maintain it, including all pipework and associated equipment, homeowners are likely to have maintenance costs to consider alongside heating charges. Whether those prove to be less or more than the costs to maintain the average gas boiler or other appliance remains to be seen.

We’ll be watching the situation with interest to see whether district heating has a bright – and warm – future.

Closed water system experts

Water Treatment Services offer a comprehensive range of solutions for the management of closed heating, chilled and cooling water systems, including district heating systems.

Find out how we can help improve the thermal performance of your closed water systems, lower energy bills, reduce maintenance costs and down-time, and extend plant life-cycles.

Our industrial water treatment experts can provide advice and full support to help you identify the most appropriate strategies for managing your water systems.

With offices in London serving the South and South East England, Manchester (North West), Birmingham (Midlands), Bristol (South East England and Wales), Leeds (North and North East) and Glasgow (Scotland), supported by regional teams of specially trained engineers, water treatment specialists and technicians we offer cost effective environmental support solutions across the whole of the UK and Ireland.

Contact us today to learn how our water management solutions can help improve the performance of your district heating systems.