Table of contents:

District heating: the advantages and disadvantages
District heating: the advantages and disadvantages

Video: District heating: the advantages and disadvantages

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Video: The Benefits and Challenges of District Heating 2023, January
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Do you have to use district heating and want to know what's coming? Or do you have a line nearby and are thinking about a connection? Read everything you need to know about district heating, how efficient or sustainable it is and more.

Table of contents Table of contents District heating at a glance: advantages, disadvantages and costs

  • benefits
  • disadvantage
  • How does district heating work?
  • Installation requirements
  • sustainability
  • Efficiency
  • costs
  • Legal provisions and grants

Table of contents Table of contents District heating at a glance: advantages, disadvantages and costs

  • benefits
  • disadvantage
  • How does district heating work?
  • Installation requirements
  • sustainability
  • Efficiency
  • costs
  • Legal provisions and grants

District heating is a collective term for different types of heating systems with one thing in common: energy is not generated where it is used. The heat is delivered from the place of generation to the place of consumption - for example in your home. Depending on the distance, a distinction is made between local heating and district heating.

District heating: what are the advantages?

  • The cost structure is clear.
  • In plants with combined heat and power, the CO 2 balance is positive.
  • The system is easy to use.
  • Small space requirement in the technical room: Especially in combination with a transfer compact station (instead of the variant with heat pump), there is no need for complex piping between the individual components of a heater. Due to the lack of a heat generator, only space is required for one store.

District heating: what are the disadvantages?

  • They are dependent on the supplier or provider through a contract. The prices can suddenly be raised.
  • Massive heat losses can be seen on the transport route.
  • Availability is limited locally.
  • You have no option with which fuel the district heating generator works. Here, if necessary, heating with fossil fuels.
  • So far there are only a few upstream power plants that generate district heating purely with renewable energies.

How does district heating work?

With district heating, heat is transported to a building. In contrast, with "normal" heating, the energy is generated on site. For example, natural gas is burned using a gas condensing heating system - heat is generated. In the case of district heating, this function is carried out by a large thermal power station or a combined heat and power plant (CHP). Waste (waste-to-energy plant), fossil fuels (coal, gas, oil) or biomass (wood chips, wood pellets) are used as raw materials. However, there are also district heating generators based on fuel cell technology or a large heat pump. The latter is mainly used when heat is a waste product due to industrial reasons, such as in data centers or refineries.

All types of power plants have in common that they always work on the principle of cogeneration. This means that not only heat is generated, but also electricity in parallel. The heat generated is transported to consumers in the form of hot water or steam through long-distance pipes. The most important component here is the insulation of the pipes. The longer the line, the more heat is lost on the way and the lower the incoming temperature. The energy loss during transport is around 5 to 20 percent. Conversely, this means that with long pipes, the water or water vapor must be heated to a higher temperature in order to guarantee the desired temperature for the consumer. If a building area is supplied with heat locally, district heating becomes local heating. There are already projects in which agricultural businesses provide the heat generated by animals as local heat to a building area. The heat arrives at the consumer at a defined transfer point. Depending on the utility company and the type of district heating provision, either a transfer station is operated directly or a heat pump is connected.

Fernwärme Kreislauf
Fernwärme Kreislauf

District heating is transported from the place of generation to the place of consumption.

Photo: Stadtwerke Kassel

In the case of a transfer station, the connected hot water tank is supplied directly with the energy provided and the water is heated. The advantage is that the transfer stations are usually small and compact, so that only the storage space in the technical room is required. It works differently with a heat pump. A brine-water heat pump is usually used, which, thanks to district heating, does not require an expensive geothermal probe or surface collectors. Instead of generating energy from the ground, the brine is heated by the district heating provided. The energy is then drawn from the brine within the heat pump and transferred to the system's hot water tank.

Fernwärmekompaktstation
Fernwärmekompaktstation

District heating compact stations are significantly smaller than a conventional heating system.

Photo: Danfoss

Installation requirements

The most important basic requirement for installing a district heating system is connection to a district heating network. The entire project of using district heating in a building depends on this. While the lack of a utility connection for gas can be compensated for by a stationary tank, there is no option for district heating. If there is no underground pipeline, there is the option of running the district heating above ground. However, both variants only make sense if there are enough customers within a defined area. For this reason, district heating is mostly found in new construction areas. With the purchase of the building land there is an obligation that the new building must be heated with district heating. This ensures that there is a high density of consumers. Only then is it worthwhile for the supplier to lay a pipe network. In existing houses, all residents would have to switch their heating to district heating at the same time so that the subsequent installation of a district heating network makes sense at all. In addition, the upstream power plant limits the possible total thermal output. With the same amount of energy, more low-energy houses can be supplied than existing buildings. It is therefore only recommended to connect surface heating to district heating, as these are operated at lower flow temperatures than radiators.

Fernwärmenetz
Fernwärmenetz

The district heating network supplies a defined area.

Photo: Stadtwerke Freiburg

Sustainability of district heating

For the consumer of district heating, it is one of the cleanest and most efficient heating methods with an extremely positive CO 2 balance. It receives the finished heat and generates no harmful CO 2 emissions through its own heating. However, the situation is different on the producer's side. So far there are only a few plants that work exclusively with renewable energies. Instead, the proportion of coal-fired power plants or thermal power plants that run on fossil fuels such as natural gas and oil is still high. When building new power plants, the focus on renewable energies becomes more and more important. As a result, newly built district heating systems are no longer based on combustion technology, but on heat pump technology. For example, large-scale heat pumps in the form of water-water heat pumps or brine-water heat pumps are installed near water bodies. In addition, existing power plants will be upgraded so that the thermal energy used to generate electricity from district heating will continue to be used (combined heat and power).

District heating is so efficient

The efficiency of district heating can be determined using the primary energy factor. This is calculated from the ratio of primary energy to final energy. The lower the factor, the more positive it is when calculating the energy saving regulation for the primary energy requirement of a building. As a result, requirements for compliance with certain values ​​of a building can be achieved more easily or a building has a better energy efficiency class (the same as the "A +" for the washing machine).

District heating: The costs at a glance

The amount of connection costs for district heating depends on the type of transfer to the house. At a transfer station by the supplier, the connection costs start at around 5, 000 euros for a low-energy house with a low heating load. The more heat there is and the more powerful the transfer station has to be dimensioned, the more expensive the connection costs will be and can also cost 10, 000 euros. If the heat is transferred to a brine-water heat pump, the pure connection fees are significantly lower. In addition, there are the costs for a brine-water heat pump. These start at around 8, 000 euros.

With district heating you have a pretty good overview of the running costs. Consumption is recorded in kilowatt hours - as with electricity - and is paid in advance at a monthly discount. This is divided into three factors:

  • Base price: A fee of 20 to 35 euros per year is payable per kilowatt of the heating load of the building. For a single-family house with a heating load of 10 kilowatts, this corresponds to an annual basic fee of 200 to 350 euros.
  • Labor price: This corresponds to the kilowatt hours actually measured. However, the price per kilowatt hour is a lot cheaper than with electricity. Costs of 6 to 11 cents per kilowatt hour are common. A purchase of 15, 000 kilowatt hours therefore leads to costs of 900 to 1, 650 euros per year.
  • Service price: Depending on the utility company, the costs for reading the measuring devices and billing are shown separately. These range from 80 to 250 euros a year. But there are also providers where these costs are already taken into account in the basic price or in the labor price.

Overall, this results in annual costs of around 1, 180 to 2, 250 euros or monthly costs in the range of around 100 to 190 euros.

The big shortcoming of district heating is the commitment to a supplier. In contrast to the electricity provider, there is no way to change the provider and get the heat from another power plant. This creates a dependency on the consumer, who could theoretically increase prices arbitrarily. A free choice of provider is not possible with district heating!

Compare the efficiency and costs of district heating with other types of heating in our compact overview.

Legal provisions and grants

For areas with district heating, a so-called "mandatory use" can be imposed. This means that other heating options are prohibited and district heating must be used as the type of heating. Conversely, there is also the legal basis for the "mandatory connection". Due to this, you can request to be connected to nearby district heating lines, although no connection was or is not planned by the supplier, for example if the line ends 100 meters from your own home. There are no requirements for district heating, such as flue gas routing using a chimney. In this regard, district heating is very straightforward.

There are various funding options for the district heating connection, so that your connection costs decrease. At the local level, depending on the utility or the municipality, there may be a bonus if you choose district heating as the type of heating. However, this differs from place to place or supplier to supplier - it is worth asking the respective provider here. The Federal Office of Economics and Export Control (BAFA) supports the construction of new district heating networks based on the Combined Heat and Power Act (KWKG). As a consumer, you have no cost advantage here, but if necessary, your home will be more quickly connected to a district heating network with the help of this support. This makes district heating one of the few systems that is currently not receiving funding from BAFA. However, the situation is different when district heating is coupled with a heat pump. This is where BAFA funding for heating with renewable energies comes into play. Up to 35 percent of the eligible costs can be reimbursed.

At KfW there are also no special grants for users of district heating. The 270 Renewable Energies - Standard and 271 Renewable Energies - Premium programs support the establishment of district and local heating networks. The positive: More and more households can be connected to district heating. In existing buildings, however, programs 124 (KfW home ownership program), 151 (energy-efficient renovation) and 167 (energy-efficient renovation - supplementary loan) give you the option of receiving a subsidy for the energetic renovation of the house in the same way as a KfW efficiency house. Programs 124 (KfW home ownership program) and 153 (energy-efficient construction) are effective in the new building, provided that they are efficiency houses in accordance with KfW specifications.

Timo Jochmann

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