From Ancient Rome to 14th century France

The Romans were the first to discover the benefits of hot water in pipes. We can trace the roots of district heating to the hot water-heated baths and greenhouses of the ancient Roman Empire.
Also, in 14th-century France, hot water was appreciated in Chaudes-Aigues, where a hot water distribution system provided heat for around 30 houses with something as modern as geothermal energy. This is regarded as the first real district heating system in the World.
1853 - Steam DH service

First-movers in North America
In Annapolis, Maryland, just 50 miles from Washington D.C. the U.S. Naval Academy started a steam district heating service in 1853. And the Massachusetts Institute of Technology (MIT) began coal-fired steam heating in 1916 when it moved to Cambridge in Massachusetts. But the first commercially successful district heating system was launched in Lockport, New York in 1877 by American hydraulic engineer Birdsill Holly. He is considered the founder of modern district heating.
The steam system currently supplying Manhattan in New York City was put into operation as early as 1882 by the New York Steam Company. It used steam from coal-fired boilers to heat the buildings. The system grew to become one of the largest district heating systems in the world, serving thousands of customers.
During World War II, district heating systems saw a surge in popularity, as they were seen to conserve energy and reduce dependence on oil. The federal government even established a program to fund the construction of new district heating systems in cities across the country.
1896 in Frankfurt, Germany

Early European development
Centrally produced district heating has existed for almost 150 years, with systems tested as far back as the late 19th century in the German city of Hamburg and New York. Germany’s first district heating system was established in Frankfurt in 1896 to supply heat to a large hospital.
1898 in Frederiksberg, Denmark

The Danish story of a waste incineration plant
In the late 19th century, both the environment and a future-orientated heat supply were put on the agenda of the city council of Frederiksberg which is an independent municipality situated in the western part of Copenhagen City. Combined heat and power production based on household waste incineration then became the starting signal for the development of district heating in the municipality.
The beginning, waste to heat in Frederiksberg
In the 19th century, Frederiksberg develops from being a village to being a town with the nature of a big city. In the middle of the century – in 1857 – Frederiksberg becomes an independent municipality ranking as market town, and during the 19th century, the city develops rapidly. Industrial enterprises are being built and the factories attract manpower. The city grows bigger and bigger – the industry grows, and the population increases. A railway station is built, a fire service is established, schools and a library are built, and the city is provided with gas, running water, sewers, and electricity.
However, the busy activity has a natural – though difficult – “by-product”: waste. Concurrently with the increase in population and the building of the outer area of Frederiksberg, the price of land increases, and it becomes even more expensive for the municipality to buy land for dumping grounds. At the same time, people are fully aware of the risk of e.g., cholera by having dumping grounds that are placed too centrally.
By the end of the 19th century, it was therefore a dubious affair to walk around in the streets of Frederiksberg. Many of the free space areas were bursting with piled up garbage with consequent odor problems. The municipality struggled with mountains of waste from the rapidly growing population. The lack of dumping grounds meant that the waste from the 75,000 inhabitants accumulated, and the fear arose that epidemics would break out. The municipality therefore had to come up with new thoughts.
In 1898 therefore, a few railway carriages were loaded with typical Frederiksberg waste and driven to Germany to investigate the possibility of following the example of Hamburg. Here, in 1896, a plant had been developed to burn waste with the facility to utilize the generated heat. The test result came out positive and in the spring of 1902 Frederiksberg Municipality decided to build Denmark´s first waste incineration plant, which not only produced heat but also electricity.
1900-1960, Europe

Development in northern Europe
Finland and Sweden
The first district heating system in Finland was established in the city of Vaasa in 1902 and the first in Sweden was established in 1920 in the city of Västerås, both with the aim of providing heat to public buildings. The first municipal district heating plant in Sweden was set up in Karlstad in 1948.
During the post-World War II period, DH systems in Finland and Sweden experienced significant growth, driven by the need to rebuild infrastructure and the desire to reduce dependence on imported oil. Many of the DH systems established during this period were supplied by coal-fired power plants.
Denmark´s first district heating power plant
In September 1903, the first waste collection was received at the new waste incineration plant and the plant was inaugurated. From December 1 that same year, the district heating production was put into regular operation. On horse-drawn carriages the waste was loaded into silos and from there, in portions, loaded further into the ovens. In the shape of steam, the heat was led through tunnels to the newly built hospital, an orphanage, and a poorhouse.
Russia
District heating in Russia dates to the early 20th century. The first district heating system in Russia was established in Moscow in 1912, with an aim to provide heat to public buildings.
During the Soviet era, DH became an important part of the country’s energy infrastructure, with the development of large-scale district heating systems in many cities. These systems primarily served residential areas and were supplied by large, centralized heat and power plants.
Poland
The first district heating system in Poland was established in 1923 in the city of Łódź, with the aim of providing heat to public buildings.
In the 1950s and 1960s, district heating systems gained popularity in Poland as a way to provide heat to large housing complexes and industrial areas. This was driven by the need to rebuild infrastructure after World War II and the desire to reduce dependence on imported oil.
During this period, several large district heating systems were developed, including the Warsaw District Heating System, which was established in 1955 and is still one of the largest district heating systems in Europe. Other major district heating systems were established in Kraków, Gdańsk, and Poznań.
France and the United Kingdom
District heating has a relatively short history in the United Kingdom and in France compared to some other European countries. The first district heating scheme in the UK was established in 1948 in Nottingham, with the aim of providing heat to a housing estate and in France in the early 1950s, in the city of Grenoble.
In the 1960s and 1970s, district heating systems gained some popularity in the UK and in France, particularly in social housing developments and some industrial areas. However, the number of district heating schemes remained relatively small, with most of them being supplied by fossil fuels.
Early development in the Netherlands
District heating, also known as heat networks, have been used in the Netherlands since the early 20th century. The first district heating system in the Netherlands was established in Rotterdam in 1923, with the aim of supplying heat to greenhouses.
In the 1960s and 1970s, district heating systems gained popularity in the Netherlands to provide heat to large housing complexes and industrial areas. This was driven by the need to reduce dependence on imported oil and gas, and to increase energy efficiency.
During this period, several large district heating systems were developed, including the Amsterdam Heat Company (AHC), which was established in 1969 to supply heat to the city of Amsterdam. Other major district heating systems were established in Rotterdam, Utrecht, and The Hague.
1920 -1960, Denmark

National development led by the local municipality in Denmark
The centralized form of heat supply grew steadily in the 20s and 30s, and gradually regular district heating substations appeared in connection with the development of large adjoining housing areas. When the power stations in the large cities changed from diesel to steam heating in the 30s, many of them were carried out as combined heat and power plants since the earlier development had obliged the stations to deliver heat as well.
During the Second World War, the lack of diesel oil made it difficult to maintain the heat supply from the combined heat and power plants. Some plant owners were therefore forced to establish backup heating, using solid fuel heat-only boilers. After the normalization of the oil deliverances, these plants represented excess capacity and therefore created a basis for expanding the heating supply networks.
After the war, the structure of the electricity supply in Denmark changed towards large central power plants, and consequently, many of the local plants were closed. This made it necessary to build heating stations to supply the already established district heating systems.
Technical progress in Denmark
Already at the beginning of the 1960’es, Denmark had more than 50 years of experience in using district heating, and the development was now strengthened by the fact that some Danish suppliers launched the idea of town development with district heating based on a low-supply temperature (up to some 90°C). Hereby the district heating stations and the distribution network would become cheaper. Also, on the operational side, this led to savings since the demands on personnel, etc., did not have to live up to the regulations for hot-water plants or power stations.
The first piping networks
The pipes of the first piping networks were made of iron and insulated with cellular concrete, but this turned out to cause corrosion of the distribution pipes, especially in cases of the nets being placed in poorly drained soil. To fight this problem, the pipes were insulated with mineral wool and hung up in concrete ducts so that they were secured against humidity. However, this solution was expensive, which made it suitable only for heat supply to major heat customers such as hospitals and industries with considerable heat consumption. Therefore, the development of new district heating systems in housing areas partially stopped for a period.
Pre-insulated heating pipes
The breakthrough for the heat supply of the housing areas came when several Danish companies developed pre-insulated district heating pipes. Here the iron pipes from the factory were covered with a heat-insulating layer of polyurethane finished by a dense non-corrodible plastic jacket. The problem with this solution was how to obtain a completely tight assembling of the pipes, but with a special technique where the joints were assembled with muffs that had been welded or screwed on, it proved a success as well. In addition, electrodes were built into the insulation layer of the pipes, which made it possible to discover any water intrusion and identify a leak so that it could be repaired relatively easily.
Surplus heat and waste incineration
Initially, the plastic jacket allowed only low temperatures, with flow temperatures preferably not exceeding about 90°C. Soon the material was improved, and the allowed temperature was raised to 120°C. The low operation temperature made it possible to utilize the surplus heat from industrial enterprises, not least from waste incineration plants. The combination of these two facts caused a boom in the establishment of district heating networks and waste incineration plants. Thus, the first post-war waste incineration plants were built at the beginning of the 1960s.
1960-1970, the United States

Natural gas is taking over in the United States
By the 1960s and 1970s, the popularity of district heating began to wane as natural gas became a cheaper and more widely available source of energy. Today, district heating is still used in some cities, particularly in northern states where it is more common to use steam to heat buildings. However, it remains a relatively niche technology compared to other heating options.
1970-1990, Europe

Newer District Heating history
1973: The energy crises boosted the development in Denmark
It is important to note that district heating in Denmark developed in the same manner as in other countries before the energy crisis hit the western countries in 1973/74. At that time, energy consumption per inhabitant was extremely high. The energy crisis created an urgent need for crucial change in the Danish energy system. As a country the whole economy was threatened because Denmark at the time imported almost 100% of all the fossil fuels required to generate heat.
For the single costumer the heating budgets were suddenly multiplied. The Danish government was forced to devise methods for saving fuels to safeguard the interests of society and to reduce the consumers costs. Several initiatives were launched, including:
- Systematic planning of the heat supply in all areas
- Greatest possible CHP generation on the basis of such planning
- Insulation of buildings
- Development of highly effective district heating pipe systems, pre-insulated pipes with high insulation properties and low installation costs
- Reduction of operating temperatures in district heating systems and a variable flow in the pipelines to secure the most economical operation in the overall production and distribution system, while at the same time allowing the possibility to apply pre-insulated pipes
For the next 40 years and still today, district heating first became and later proved itself to be a reliable, cost efficient and green source of energy to the benefit of Denmark. Due to a firm energy policy and cooperation between central and local authorities, heat supplying companies and private companies, considerable results were achieved in Denmark during the period since the energy crisis. This has, among other things, meant that here at the beginning of the 21st century, the energy requirements per inhabitant for space heating have dropped a little more than 50% of the requirement in 1973. The success story was created by several technical and political initiatives, the following describes some of the most important.
1970-1980: Expansion and shift to renewable energy sources in Europe
In the 1970s and 1980s we see a significant shift towards renewable energy sources in several European countries due to the rising energy prices following the oil crisis. Poland and Germany experience a significant expansion of district heating, driven by government policies that promoted energy conservation and renewable energy. In Poland the total installed capacity of DH systems increased from around 3 GW in 1970 to around 22 GW in 1990. In Germany the total installed capacity of DH systems increased from around 4 GW in 1970 to 40 GW in 1990. Also, in Finland and Sweden there was a significant shift towards renewable energy sources including the use of wood and peat for district heating driven by government policies that promoted energy conservation and renewable energy.
1980-1990: Expansion in urban areas
In France and the United Kingdom there was a significant expansion of district heating, particularly in urban areas. This was driven by government policies that encouraged the use of renewable energy and energy efficiency measures. In the UK, some large DH schemes were developed during this period, including the Sheffield District Energy Scheme and the Southampton District Heating Scheme. In France, the Paris District Heating Scheme was developed in 1984 and it is still one of the largest district heating systems in Europe.
In the Netherlands, on the contrary, there was a slowdown in the development of district heating during the 1980s and 1990s, due to low oil prices and a focus on individual heating systems.
2000-2030, Europe

Recent years until today
European countries with focus on the green transition
In recent years, there has been renewed interest in district heating in both the Netherlands, Germany and Poland to reduce greenhouse emissions and increase energy efficiency. Currently, the Netherlands has around 25 district heating systems in operation, with a total installed capacity of around 3.5 GW. Germany has more than 6,000 district heating systems in operation, with a total installed capacity of around 25 GW. Today, Poland has more than 1,500 district heating systems in operation, with a total of around 22 GW. France has more than 600 district heating systems in operation, with a total capacity of around 15 GW.
In all these European countries, the systems primarily serve large housing complexes, hospitals, universities, and industrial areas and are supplied by a mix of renewable and non-renewable energy sources.
If you’re curious about the history of district heating, you’ll definitely want to check out some of the great articles available in the Hot|Cool magazine.
District heating has been around for over a century, and it’s a fascinating topic with a rich history. One article you might want to start with is “District Heating in Greater Copenhagen”, written by Lars Gullev. This article provides a comprehensive overview of the development of district heating systems, starting in 1903 in Frederiksberg to present day Copenhagen. It covers the key technological and economic drivers that have influenced the development of district heating, as well as some of the challenges and obstacles that have been faced along the way.
Another great article to check out is “Combined Heat & Power”, written by Katinka Johansen. This article focuses specifically on the history of district heating in Denmark, and how it has evolved over the years to become an important part of the region’s energy mix. It highlights the heat infrastructure planning in Denmark, and explores some of the reasons why it has been so successful in this part of the world.
Overall, if you’re interested in learning more about district heating, Hot Cool is a great place to start. With a wealth of informative and engaging articles available, you’re sure to find something that piques your interest and helps you gain a deeper understanding of this fascinating topic.