by Linda Bertelsen
Europe at night as seen from space with city lights reveals human activity in Germany, France, Spain, Italy, and other countries

Although there are several tools for project feasibility studies, few software programs provide data and scientific calculation methods to perform strategic energy planning at a city or regional scale. That is why a group of research institutes and cities have developed the Hotmaps toolbox in the framework of a European project. City planners, consultancies and utilities can now access data and calculation modules for the entire European Union. The application of the toolbox in seven pilot areas has already brought some results and advanced their transition towards a greener future.

By Sara Giovannini, Policy and Communication Officer at Energy Cities; Lukas Kranzl, Senior Scientist at TU Wien; Marcus Hummel, Managing Director at e-think – energy research

An urgent need to support strategic planning of cities

According to the European Commission, “Becoming the world’s first climate-neutral continent by 2050 is the greatest challenge and opportunity of our times”. The European Union, but also its national and local governments are setting up ambitious plans to reach this goal.

However, if we want to succeed, we should look at the heating and cooling (H&C) sector more carefully. Heating and cooling accounts for the largest share of energy consumption in cities (where 75 % of the EU population live): new technical, regulatory and governance frameworks are necessary to transition to a more sustainable and green system.

In most European cities and regions, there is a need to better identify, analyze and map resources and solutions to decrease energy demand on one hand and to meet the remaining demand with green, efficient, and cost-effective energy sources on the other hand.

Thanks to strategic energy planning, including H&C, we can promote the transition to a more flexible integrated energy system with a focus on energy efficiency and renewable energy. However, knowledge, access to data, and resources for cities to perform this analysis are often lacking.

Figure 1 a screenshot from the Hotmaps.eu website

Figure 1 a screenshot from the Hotmaps.eu website

A toolbox and a large data set for Europe is now available for free for city planners

The Hotmaps project addresses this challenge. Leading research institutions in Europe developed a GIS-based website that allows you to have in just 5 minutes an estimate of H&C demand in your region and the potential of local renewable energy to cover this demand. By performing more detailed analyses, the tool supports the development of fully-fledged heating and cooling strategies.

The Hotmaps software is

  • Fast: it provides a quick indication about which direction to go, to kick-start detailed technical planning.
  • Free and open-source: it is available online, with no fees. You don’t need to install additional tools.
  • Easy to use: no need to be a GIS expert, the software combines web-based visualization of GIS data with a flexible selection tool. Data are visualized directly on the website.
  • Adaptable: You can retrieve indicators at various geographical and administrative levels. Moreover, you can upload your data to your account and use it to elaborate comprehensive heating and cooling strategies for your area of interest.

Hotmaps provides a large array of data sets with detailed resolution: from NUTS0 data down to LAU2 and even Hectare-level. Default data is available for the entire EU27 area, UK, and Switzerland, intending to support local, regional, and national H&C planning . Hotmaps open-source data sets provide information on:

  • Building stock;
  • Space heating, cooling, and domestic hot water demand;
  • Climate context;
  • Industrial processes;
  • Heating and cooling supply;
  • Renewable energy sources data collection and potential review;
  • Hourly load profiles.

Hotmaps dataset is good, but using local data is always better

Hotmaps especially provides open GIS data on the distribution of heat demand (HD) in buildings, based on gross floor area (GFA) data. Researchers broke down energy demand data from the national level to the local level using several other (open) data sets.

The data collected with a top-down approach was compared with other sources for 20 selected areas across Europe. The average difference of all compared values was 12% (median 8%), with a standard deviation of 10%.A comparison of the developed maps

with maps based on municipal building stock datasets (bottom-up approach) for three cities shows that, for these locations, the overall tendency of the distribution of gross floor areas and heat density is similar in both approaches.

In figure 2, you can see the difference between bottom-up and top-down dataset. The blue dots indicate that the Hotmaps’ top-down data assign a lower share of energy or gross floor area to a specific hectare cell compared to the bottom-up data (and vice versa for the red dots).

Therefore, the developed datasets seem to systematically overestimate the GFA and HD in low-density areas and underestimate the GFA and HD in high-density areas.

Figure 2 : Difference between the top-down and bottom-up values for each hectare element in three cities: (a) gross floor area (GFA) of all buildings (including industrial and non-energy relevant buildings) in the bottom-up data vs. heated area (HA) in the top-down data (left column), (b) HA in the bottom-up data vs. HA in the top-down data (middle column), and (c) heat demand in the bottom-up and the top-down data (right column). (Müller et al., 2019)

Figure 2 : Difference between the top-down and bottom-up values for each hectare element in three cities: (a) gross floor area (GFA) of all buildings (including industrial and non-energy relevant buildings) in the bottom-up data vs. heated area (HA) in the top-down data (left column), (b) HA in the bottom-up data vs. HA in the top-down data (middle column), and (c) heat demand in the bottom-up and the top-down data (right column). (Müller et al., 2019)

Therefore, we believe that the Hotmaps dataset allows performing the first analysis for strategic heat planning, including the identification of areas that might be suitable for district heating. For the detailed planning of supply infrastructure, however, users can upload their own data in the toolbox to get results that are more accurate.

Quantitative results are key to prioritize long-term scenarios

The Hotmaps toolbox was developed together with cities, to make it useful for local/regional/national authorities, and urban planners. Seven European pilot areas have been successfully testing it, to develop their heating or cooling strategies: Aalborg (Denmark), Bistrita (Romania), Frankfurt (Germany), Geneva (Switzerland), Kerry County (Ireland), Milton Keynes (UK) and San Sebastián (Spain).

These strategies have identified promising scenarios for a decarbonized H&C sector in 2050 with a mix of building renovation, district heating, and decentralized renewable systems. They resulted from qualitative and quantitative analyses as well as discussions with stakeholders and revealed interesting opportunities on the way forward. Thanks to the Hotmaps toolbox, cities could identify the cheapest supply areas for different types of district heating grids systems.

For example, it turned out that investing in a district heating grid connected to a waste incineration plant together with using excess heat in the wastewater treatment plant could be an economically interesting option for the City of Bistrita, and should be further explored.

In Geneva, there are great opportunities for using the ambient heat of lake water in a low-temperature district heating grid. For Frankfurt, the exploitation of heat sources using different types of heat pumps feeding into district heating grids will be one of the pillars of a decarbonized heating system. Industrial excess heat, excess heat from data centers, river water, and ground heat will play a key role in this context.

However, due to the high heat density in the city and the limitations for renewable energy and excess heat sources to provide peak power, a strong focus will also lie in reducing energy demand. A reduction of the space and water heating demand of around 50% by the year 2050 might be needed to meet CO2 emission reduction targets.

Thanks to Hotmaps, users can obtain a large-scale vision of the whole city, allowing them to identify energy-related issues very easily. Hotmaps helps gather all the information required to identify planning priorities for the future and can be used as a decision-making tool, to create different energy scenarios. It helped cities to bring together all the actors of the energy sector, to refine their knowledge of the territory, and to share data and analysis.

“Thanks to Hotmaps, we have a quick overview of where the heat demand is high enough to invest in district heating pipelines. This enables us to easily identify hot spots, which our energy utility can then investigate in more detail. A strategy across city boundaries is also made easy with the default data.”

Strategic heating planning is the unavoidable step towards decarbonization

Cities are not the only potential user of Hotmaps. The tool can support consultancy companies advising local authorities in the development of their sustainable energy and climate action plans, and utilities willing to identify new potential geographical areas to be supplied by district heating.

“The Hotmaps toolbox has been useful to identify and verify additional resources in our area, not just for heating/cooling networks, but other sources of locally generated energy.”

The elaboration of spatially differentiated strategic plans for different districts of a city will avoid uncoordinated projects, harmonizing energy, and urban planning. The ultimate goal is to decarbonize the building stock, which would be beneficial for the entire heating and cooling sector and the economies of cities. Utilities and consultancy companies have thus interest in collaborating with cities to build shared local visions.

The tool can also be used to support strategic macro-planning processes on a national level, such as the update of the comprehensive assessment of efficiency in H&C. According to article 14 of the Energy Efficiency Directive, the EU Member States have to perform this exercise by the end of 2020. Several governments have already expressed their interest in using Hotmaps.

For further information please contact: Lukas Kranzl kranzl@eeg.tuwien.ac.at

Meet the authors

Sara Giovannini
Policy and Communication Officer at Energy Cities
Lukas Kranzl
Senior Scientist at TU Wien
Marcus Hummel
Managing Director at e-think – energy research
“HOTMAPS – Heating and cooling data for all of Europe” was published in Hot Cool, edition no. 2/2020. You can download the article here: