District Heating: What Are They and How They Drive Energy Efficiency in City Councils

District Heating: What Are They and How They Drive Energy Efficiency in City Councils

More than 50% of the final useful energy demand in the EU comes from the heating and cooling consumption of buildings. The installation of District Heating in cities and municipalities helps improve their energy efficiency, resulting in energy savings and reduced costs for their inhabitants.

If you are thinking of setting up such a core network in your municipality, this article will help you to better understand this concept and learn about examples from other cities, which will inspire you.

What is District Heating?

District Heating also known as heat networks or teleheating, is a system of domestic hot water and heating supply that, through a network of pipes, reaches different buildings from a central plant.

Beyond this definition, it is perhaps easier to understand the concept of a central heating network with a simple example. Think about how heating works in a home with natural gas. The boiler takes water from the network, heats it and makes it circulate it around the house.

In a central heating and cooling network, the water is heated in a central plant that is not in our home. It can be in the building, in the urbanization, or even further away, such as at the entrance of our district.

This type of centralized systems can vary both in the energy sources used and in size. And they can cover from a small number of buildings or dwellings, to entire metropolitan areas and even large livestock farms.

As with heating, this centralised model can be applied to cooling. This is known as central cooling networks or District Cooling (DC). And, of course, systems combining both are also beginning to be deployed.

District heating and District Cooling structures

To understand how a District Heating (DH), District Cooling (DC) or combined (DHC) system works, it’s necessary  to understand its different parts. This is the most common structure in central heating and cooling networks:

The thermal power station: This is where all the heat, cold or hot water, that the network installed in your municipality or city demands, will be generated. They are usually outside urban areas. In addition, they can produce their own energy based on fossil fuels, renewable energy and the upward trend: biomass.

– The distribution network: It is a network of underground pipes that distributes the product from the thermal power station to the buildings of your city. The pipes have two directions: propulsion and return. The distribution network can be as extensive as necessary to bring heat, cold or hot water from production to consumption.

You must bear in mind that this extension will influence the effectiveness of the network. For example, the closer the two points are, the less energy losses will exist in the network.

Thermal transmission substations in buildings: These are the ones that allow energy to be distributed to consumers. In a residential building, they provide floor-to-storey distribution, for example. The substations are responsible for adapting the pressure and temperature of the distribution network to the conditions of each building.

Why District Heating and District Cooling are efficient

More than 50% of the final useful energy demand in the European Union comes from heating and cooling consumption. Did you know that district heating consumption represents more than 9% of heating consumed in the EU?

In addition, a district heating system can integrate renewable energies as well as geothermal and solar thermal energies, municipal waste and waste heat. This is very interesting if your city wants to make the most out of the energy sources it already has.

In some cases, these centralized networks also have a supply of chilled water from the same plant where the hot water is produced.

The “Intelligent Buildings” already mentioned in other articles, which are connected to an intelligent network of remote control or automated heating and cooling, will be able to manage more efficiently the appliances depending on the date and time, the humidity, the external wind chill, and of course, the occupation of the building.

Technologies such as the Internet of Things (IoT) are enabling greater flexibility, control and synergies in building management. Intelligent building management systems can be applied not only to an individual building, but also to energy supply systems such as DH/DC. These systems can measure consumption in the areas where it is most in demand and where its supply can be adjusted if it is not being consumed at that moment and so on.

Additionally, this type of facilities is not just interesting for their installation in residential neighbourhoods.

From the point of view of energy efficiency for municipalities, central heating networks are an ideal solution in commercial, tourist, industrial complexes, hotels or offices. In other words, in any group of buildings that need to be heated and/or cooled.

As the generation of heat energy is done jointly, it is a very efficient option for both the measurement of their energy efficiency and the achievement of improvements for municipalities.
Now, are you curious to know more about building management technologies? Why not take a look at other articles on our blog? Building Technology: Who’s Who?


Why Cities are Implementing District Heating

District heating has a long tradition in countries with cold winters such as Finland, Sweden and Norway. For example, in the city of Helsinki (Finland), 90% of the energy consumption by heating systems is produced by thermal power plants that are distributed through pipe networks throughout the city.

Installations of central heating and cooling networks not only have ecological benefits, by reducing CO2 emissions, they also highlight economic advantages such as:

  1. Reduces the cost of operation and maintenance of the installation.
  2. It generates local employment.
  3. The installations are amortised in less than 10 years and allow access to subsidies within Renewable Energy and Energy Efficiency programs from the EU or at national scale.  The Energy Company Obligation (ECO), a government energy efficiency scheme in Great Britain, is an example, allowing British households to be funded by energy suppliers for the installation of energy efficiency measures.
  4. It reduces the installed power per dwelling and the consumption per dwelling.
  5. It avoids the problems associated with low efficiency in old boilers.
  6. It avoids the manipulation and storage of fuel in the building, improving aspects such as security, dirt and space.
  7. And it reduces the noise of the installations in the buildings, since it does not have thermos installations.

All these benefits are very attractive for your town hall for several reasons:

  • The existing legislation in Spain is becoming more and more restrictive and forces big cities to reduce emissions, something that can be improved with DH, DC.
  • It improves energy efficiency in the municipality, with energy savings, and the possibility of being able to control and measure it through energy management applications offered today by technologies such as IoT.
  • Greater access to subventions and subsidies for municipalities that reduce their CO2 emissions, IDAE 2017 (Spain).

Other examples, at the EU Include:

  • ELENA (European Local Energy Assistance): The European Commission will provide funding for EUR 97 million to ELENA, in order to support project development services for energy efficiency in privately and publicly owned housing.
  • Fifteen councils in Scotland have received more that £2 million by the Scottish Government in order to help businesses and homeowners install energy efficiency measures as part of the new Energy Efficient Scotland programme.

The Affordable Warmth Scheme is available for Northern Ireland and its goal is to help people with an income lower than £20.000 per year and live in a targeted area by their council make thier homes warmer, healthier and more energy efficient.

European cities with central heating and cooling networks (DH and DC)

The European average for district heating and district cooling systems is above 12%. Among the pioneering countries, we find the Nordic countries and central Europe, from which we will highlight Helsinki and Vienna as exemplary cities with central heating and cooling networks.

Helsinki has a heat network that covers more than 90% of the city’s total heat demand. It covers an area of 1.200 km and supplies more than 10.000 users, reflecting the importance of this type of energy supply systems for the city. However, being a city with extreme cold weather conditions doesn’t mean it has missed the option of cohesive heat with cold, so this network also has a distribution of refrigeration. The EU considers it to be an example of an urban heat and cold network.

In the case of Vienna, the city has a heating and cooling network supplied by 3 plants located in the urban area. The Spittelau plant is not only a waste management company that provides the energy for part of the city heating system, it is also a tourist attraction due to the design of the building. An example not only of energy efficiency but also of the integration into urban architecture.

45% of the energy used for heating and cooling in the EU is consumed in the housing sector, 37% in industry and 18% in the services sector. Each sector has the potential to reduce demand, increase efficiency and switch to renewable energy sources.

Spanish cities with District Heating

According to the 2018 census of heat and cold presented by the Association of Heat and Cold Network Companies, ADHAC (in Spanish), which prepares with the Institute for the Diversification and Saving of Energy, IDAE, Spain already has 402 District Heating networks.

These networks already supply energy to more than 5.000 buildings, with an extension of almost 680 km. These figures represent a saving of 305.945 Tn of CO2 per year and an average saving of 79% in the consumption of fossil fuels. 

Source (Spanish): http://www.adhac.es/Priv/ClientsImages/AsociacionPerso8_1540226118.pdf

According to ADHAC the Spanish market of the district heating only represents 1% of users, very far from the European average. But ADHAC’s intention is to boost the market in Spain, since this type of centralised networks provides energy cost savings in homes and the country as a whole.

Some examples of Spanish municipalities that have installations of central heat networks are the city of Barcelona, or the recent District heating opened just 1 year ago in Móstoles, which is the largest in Spain so far. 

The case of the city of Barcelona

Another example of central heating and cooling networks is in the city of Barcelona, where the areas of the Forum and the 22@ technology district have a central in the Fòrum area – which uses steam from the incineration of urban waste and condenses its equipment using seawater – and a second central in the 22@ district.

The network has a length of 14 km and serves 80 buildings, air conditioning an area of 760.000 m². The connected heat power is 51 MW, and the cold power is 73 MW. Installed cooling capacity is 35.9 MWh, with an accumulated cold water power of 40 MWh and another in the ice storage tanks of 80 MWh.

The case of the city of Móstoles

In 2017 the largest District Heating network in Spain was opened in the city of Móstoles. This central heating network will serve 6.500 homes, corresponding to 13 communities of neighbours, thanks to a biomass plant of 12 MW.

80% of the energy generated in the plant is destined to produce heat, to heat the houses and the remaining 20% to produce hot sanitary water.

In 2018 there was an increase in local networks in most autonomous communities. Among those that have registered an increase in the number of registered networks, Catalonia stands out. This has 12 new facilities, where the development of district networks has been remarkable in recent years.

32.3% of installed capacity is in Catalonia (495 MW), followed by Madrid, whose 342 MW represent 23.6% of the 1.448 MW installed throughout the country.

If you currently manage energy projects in municipalities, you will agree with me that betting on an intelligent energy management is one of the best ways to reduce costs. This is why many municipalities are investing in District Heating and Cooling facilities.

Monitoring the energy consumption and operation of these facilities is crucial in this type of project. Why? Because they depend on a large economic investment to carry them out. That’s why I suggest propose that you go one step further, making advanced analyses and obtaining reports that will help you demonstrate the ROI of the project.  The DEXMA Platform is the most advanced on the market and with its help, you will be assured of personalised results and reports. We recommend you to try it!