The Utility Saving Expert guide to District Heating

An innovative solution for domestic heating systems

Homes, businesses and public buildings can get a supply of low-carbon energy by using district heating. Energy efficient and good for the environment, district heating presents a less wasteful source of energy that can deliver heat and power to an entire community.

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Providing a solution to some of the most common problems with the supply of energy, district heating creates a community system by providing a central energy for multiple households or businesses, instead of each household or business premise needing to rely on its own boiler.

As each location is powered by the energy centre, instead of individual boilers, this creates a more eco-friendly system with less waste because it makes better use of heat and power. It's viewed as an innovative way to provide heat and hot water to multiple properties.

What district heating means

As the name suggests, district heating is a method of supplying heat and hot water to an entire area, or "district" of buildings, from a single system. This means that a community uses a shared supply of energy instead of each relying on different heating systems, so homes and businesses are supplied with heating and hot water on a community basis.

Heating networks are often supplied with excess energy created by industry to make use of otherwise wasted energy, or through renewable sources. Furthermore, by sharing the supply, these properties waste less energy in their own households. Using a central supply removes the scenario where excess hot water is unused and wasted, and involves a single system instead of mutiple boilers heating up in various locations.

Sometimes referred to as teleheating or heat networks, district heating is becoming increasingly popular in the UK.

The history of district heating

District heating is an innovative technology that comes from Denmark. Through its district heating networks, Denmark supplies energy into six large central networks for major cities and urban regions, plus 400 decentralised zones across the rest of the country.

As one of the world's most energy-efficient countries, it's no surprise that around two thirds of Danish households are connected to district heating. In fact, the widespread use of district heating is a major contributing factor to Denmark's low carbon emissions, which have been decreasing over the past decades.

Denmark's district heating timeline

  • 1903 - Denmark built its first combined heat and power plant, which was also a sustainable waste management plant.
  • 1920-30s - Denmark developed district heating systems using wasted heat from electricity production.
  • 1970s - Following the oil crisis, there was a rapid expansion of collective district heating systems in Denmark, including vast pipe installation under towns and cities.

However, the idea of collective heating and hot water runs further back in the history books, as early as the Roman Baths. In one form or another, similar systems have existed in:

  • Ancient Rome
  • Medieval Europe
  • The USA in the industrial age
  • Eastern Europe in the Soviet era

District heating in the UK

In the 1950s, the UK built its first district heating network to reduce carbon emissions and operational costs. This was the Pimlico District Heating Undertaking (PDHU), which used waste heat from the old Battersea Power Station that was transported to Pimlico by being pumped under the River Thames.

Within eight years of being connected to the district heating system, Battersea had become one of the world's most efficient power stations of its time, operating with a thermal efficiency of 25 percent.

The district heating in Pimlico has since transitioned to a new energy centre to heat the water and is still operational today.

Despite this early uptake of district heating, the innovative method of supplying homes and businesses with heating and hot water on a collective basis is still less common in the UK, and currently, less than 5 percent of heating energy in the UK is sourced from low carbon supplies.

However, an investment of £40 million from the UK Government was launched in February 2020, together with an announcement that seven new district heating network projects are planned.

Most effective in an urban landscape, it's likely that district heating will become more widespread in densely populated cities and may help to tackle fuel poverty in these areas, whilst reducing housing management costs.

The heat networks will be built in London, Leeds, Bristol and Liverpool, supplying clean power to around 30,000 homes, giving residents access to low carbon heating. This is expected to reduce more than 150,000 tonnes of carbon over the course of fifteen years, the equivalent of planting 400,000 trees.

The investment demonstrates that whilst district heating may require up-front costs, it is a forward-thinking approach that will be cost-effective and energy-efficient in the long term.

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How district heating works

District heating systems provide a central supply of energy to a network of properties. This means that instead of each household using an individual boiler and pipe network, district heating schemes rely on large, centralised energy centres to supply energy.

Heat networks can vary in size. Some energy centres are extensive, but the size and scale of each centre will depend largely on the network it serves. For a smaller community of homes and businesses, generation and storage plants will be smaller.

The production of energy usually involves sustainable or renewable technologies that provide heat, hot water and power through a district heating and cooling pipe network. Typically, this involves insulated pipes that run underground to deliver hot water.

For heat networks that don't already use clean energy, introducing reasonably-priced energy sources that use less carbon can be done quitely over time, without requiring roads to be dug up or changes to people's homes.

Although the source of energy will be supplied to an entire community, each resident will still be able to control the heating, power and hot water in their own home. Rather than setting a boiler, residents who live in a household that is supplied through a district heating network will use a Heat Interface Unit (HIU) to control their energy usage. This is usually monitored by a heat meter or water meter.

Why district heating is energy efficient

By making use of heat that would otherwise be wasted, district heating schemes offer an environmentally-friendly option for household or business heating, provided you are located in an area that is covered by district heating networks.

Some district heating schemes redistribute excess energy from industrial plants, power plants and public transport systems, whereas others use renewable energy schemes.

In terms of renewables, district heating networks are well positioned for tansporting geothermal energy and water, tapping into natural heat supplies. For example, Iceland's capital city Reykjavík serves more than half of the country with geothermal water, making it the world's largest municipal geothermal heating service.

District heating also helps solve the problem of storing excess energy created by solar and wind power that needs to be saved for use during periods with less sun and wind. Central energy centres have the capacity for this and invest in technology that can store excess power, which would be difficult for a single household or business to do.

Finally, district energy systems are beneficial simply because of the economy of scale of heating a district with a single system. Each home or business within the community will encounter the cost advantages of the efficient production of low-carbon energy.

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