Heating homes in the city of Europolis
The European heat transition is not as advanced as the electricity transition. What are the special features of the heating sector as compared to the other energy sectors? This article portrays differences, difficulties, and opportunities.
Europolis – in the heart of Europe
Imagine yourself living in Europolis. Europolis is a medium-sized city with 200.000 inhabitants, deep in the centre of Europe. It is not particularly wealthy, but not particularly poor either. There is something very special about the energy transition in Europolis: The state of the city on its path towards climate neutrality resembles exactly the European average . The renewable shares, the number of electric charging stations, the district heating grid connection rate – they are just as advanced or lagging as in the rest of Europe.
This implies that the energy sectors exhibit very different shares of renewables; around 35% of the electricity consumed in the city comes from renewable sources. The heating and cooling demand are covered mainly by fossil fuels, such as oil and gas, with only 20% provided by renewables. And the transport sector is far behind this: Renewable sources power only around 9% of the city’s mobility needs.
Let’s stay with the heating in Europolis: What is so special about this sector’s transition towards climate neutrality? There are three important aspects that apply to Europolis and many other cities all over Europe:
1. The debate around the supply- and demand-focused strategy,
2. The switch from invisible, outsourced heat generation based on fossil fuels towards local generation by renewable sources,
3. The challenge of decarbonising a sector with a multitude of decentralised decision-makers.
A specific subsector of the heating sector, industrial process heating, requires heat on higher temperature (and sometimes pressure) level, as compared to buildings. Let’s discard the process heat in Europolis for now and focus on building heat.
Decarbonising heat supply – or reducing heat demand?
The two components of renewable heat generation and building efficiency must go hand in hand! Building efficiency in Europolis is important because 35% of its buildings were constructed before energetic standards were introduced (1970), meaning that the building stock is energetically rather inefficient . Therefore energetic renovation of buildings is really important and has a great potential to reduce CO2 emissions.
Still, in some cases, efficiency measures do not show the expected outcome in reduced heating demand. One reason for that might be the rebound effect. After reaching a higher building efficiency, Europolis’ inhabitants tend to adjust the room temperature towards a higher temperature level for increased comfort. In the end, this results in the same heat consumption.
Another trend in Europolis is bigger houses. Also, more people tend to live alone in their apartments, thus they need more area to live in. The tendency towards more space per person includes that an increased space must be heated, too.
Generating renewable heat locally instead of importing fossil fuels
Okay, so Europolis should generate heat from renewable sources. Or Europolis should at least consume renewable heat – maybe generation ‘bit’ can be located elsewhere in the countryside, just as the wind parks and photovoltaic plants generating renewable electricity?
Unfortunately, this is not really possible in the case of heat generation. Transporting heat is technically realisable but not economically feasible in many cases. Right now, Europolis’ inhabitants get heat using natural gas and oil – which is sourced outside of the city, even outside of Europe and transported in its gaseous or liquid state. However, transitioning means that more renewable ambient sources will be utilised directly: solar thermal energy, ambient heat stored in the air, in rivers, lakes and coastal water and the underground. The corresponding generation units must be placed in proximity to the heat consumers, thus require space in the urban landscape.
Solid biomass (used in pellet stoves) and synthetic gases will be of importance, too. Most probably, they will not be available in large quantities for heating of buildings, since their sustainable potential is limited. Also, the industry needs these resources for generating process heat at higher temperature levels. The low-temperature building heat can be covered by less scarce or expensive sources.
Convincing thousands of investors – the role of real estate owners
Most people in Europolis have small power units in their basements, fuelled by gas, oil, wood and sometimes even coal. The structure of many decentralised generation units distributed over the city is distinct to the heating sector – electricity-wise people are connected to one central grid.
The decentralised building sector has many individual decision-makers, investors, and thus potential early adopters or restrainers of the heat transition. But their decisions are not necessarily the most efficient and sustainable decisions for society. They are generally taken from a perspective of self-interest, with each agent pursuing their subjectively defined optimal end.
Currently, heating with fossil fuels is less expensive, but fortunately, they tend to increase due to carbon pricing. At the same time, prices of renewable heat generation continue to decrease due to technology and manufacturing development. Subsidies for renewable heating technologies and efficiency measures are very important to help reach a level playing field.
How will the Europolis heating sector look 30 years from now?
First, Europolis will reduce its heat consumption drastically. Ten years from now heat consumption will be reduced by around 20%, and 30 years from now, it will be reduced by almost 50%. Heat pumps will be the standard heating system in decentralised heating, penetrating more than 80% of the buildings which are not connected to Europolis’ district heating grids.
District heating grids transporting heat in pipelines to the residents will hold an important role in urban Europolis districts. The centralised generation makes it easy to decarbonise fast and in huge steps. Solar thermal and geothermal heat will be the dominant technologies for centralised heat generation. Also, large-scale heat pumps utilising air and surface water – operating with renewable electricity, that goes without saying.
The heating sector shows huge differences compared to other energy sectors. Some specific features hold challenges, as the implementation of local renewable heat generation units in urban landscapes and the decentralised structure of the current heat supply.
At the same time, it involves opportunities: For implementing the heat transition, the habitants of Europolis have to be involved. Solutions are to be implemented within the city and districts in Europolis. What renewable heating sources are to be used? What is the overall heating strategy of Europolis? How can carbon neutral heating be implemented in certain districts of the city? If done correctly, the heat transition might also be a transition towards greater democratic involvement of the citizens.
 The numbers stated for “Europolis” status quo situation in this text are the current average values of the EU. The future projections are based on energy scenarios for the German energy/building sector.
 Climate Action Tracker (2019b): Country Summary – EU. (https://climateactiontracker.org/countries/eu/;)
EU Building stock Observatory EU Buildings Factsheets | Energy (europa.eu)
 Scenario 95 % greenhouse gas reduction in BDI (2018): Klimapfade für Deutschland.