URBAN THERMAL ENERGY PLANNING – A BOOSTER FOR DISTRICT HEATING?

The state of Baden-Württemberg introduces compulsory municipal heat planning for the biggest cities in the state. For the first time, the cities must develop a vision for their carbon-free heat supply in 2050. The Danish example was successfully adapted to German boundary conditions. We expect the obligation to craft the first municipal heat plans to boost district heating systems in southwest Germany. This experience can then be a role model for other regions or states.

By Dr. Volker Kienzlen, KEA climate protection and energy agency Baden-Württemberg

Today, only a few cities have a clear vision of how to decarbonize their heat supply within the coming decades. In Baden-Württemberg, the climate protection law obliges 103 cities and towns to work out their vision for a fossil-free heat supply by 2050 and to develop a roadmap.

These cities are home to 5,5 million—people and thus half of the state´s population. The parliament finally adopted the state’s climate protection law amendment from 2013 on October 14th, 2020.

With this amendment, Baden-Württemberg will pave the way towards a carbon-free thermal energy supply for the cities.

The cornerstones of the amendment were discussed already in 2018, but the political process was somewhat lengthy. Ultimately, it took almost two years to agree on the regulations. From an energy efficiency point of view, these are the most critical topics:

• Compulsory municipal heat planning for all cities with more than 20’000 inhabitants: (energy needs, potentials to reduce the energy consumption, potentials of renewable energies and excess heat, necessary areas, strategy for implementation)
• All 1,100 municipalities in Baden-Württemberg must submit their data on the energy consumption of the municipal building stock to an online database. This requirement intends to push municipalities towards effective energy management. To this end, KEA-BW has developed – together with three other state energy agencies – the toolbox Kom.EMS helps municipalities manage the municipal building stock systematically.
• PV will be required on all new non-residential buildings and parking lots for more than 75 cars from 2022 on.
• Climate mobility plans are introduced for cities.
• A tool to foster sustainable construction, NBBW, will be implemented in all grant schemes.

This article will focus on the requirements for municipal heat planning.

Municipalities need a clear strategy if the transition towards a carbon-free heat supply is successful. This strategy must be local; local boundary conditions must be considered.

In the first step, the energy consumption status quo must be analyzed. One element is a map showing the building type and the age of the buildings. This information already forms a valuable basis for the heat demand of residential buildings.

The amendment explicitly allows municipalities to gather heat consumption data, i.e., data from utilities or chimney sweeps, who own a good database of all installed heating systems.

They are also obliged to provide their data for the forthcoming planning process. Such data are essential to get a proper image of the current situation of the heat supply.

Furthermore, municipalities have the right to use data available within the administration. Of course, the data privacy regulations have to be observed during the entire planning process.

The next step covers the analysis of the potential to reduce the energy demand and supply fossil-free energy. Depending on the age and type of the building, thermal insulation can be applied. The municipalities have different kinds of enterprises. Thus, there is further potential to use excess heat. Sewage pipes and wastewater treatment plants are at least a valuable energy source in each municipality.

The use of renewable energies mainly depends on the available space, i.e., for big solar thermal and PV installations close to the municipality and the access to environmental heat sources.

Based on the status quo and the analysis of the potentials, a scenario for the fossil-free heat consumption of the whole city is then developed. It covers the demand for residential buildings and industry needs, including process heat. Boundary conditions concerning the availability and price of green electricity and green gas also have to be observed.

As a result, the municipality obtains a city map showing neighborhoods suitable for district heating, neighborhoods for heat pumps, and maybe some buildings where biomass is the suitable energy source. In any case, we expect the potential for district heating to be severalfold of today’s level.

The final step of the planning process is a local strategy for the transition of the heating sector. How will the city reach its targets within the given 30 years? This transformation strategy describes concrete measures necessary to become carbon neutral by 2050 the latest.

The results must be submitted to the regional council, where an evaluation can be made.

The visits of ministry delegations to Denmark in the German-Danish Energy Dialog framework showed the effect of an obligation for urban thermal energy planning. Minister Untersteller signed an MoU 2017(??)). Projects with the Danish Energy Agency supported the process.

In parallel to the legislative process, the state government initiated a pilot project in three cities in Baden-Württemberg. The cities are different in size, ranging from 20.000 to 230.000 inhabitants (Freiburg, Baden-Baden, and Rastatt).

Each project was conducted by a different engineering company. This pilot phase was closely followed by the Ministry for Environment and the KEA Climate Protection and Energy Agency (KEA-BW).

The findings of this initial phase are summarized in a guidebook drafted by KEA-BW and published at the end of this year. A valuable input was the “Experience with Heat Planning in Denmark” report by the Danish Energy Agency.

The cities have to finalize their plans by the end of 2023. KEA-BW will assist them on their way: KEA-BW will manage a network of municipalities obliged to participate in municipal heat planning. We supply a list of FAQs and are available for individual problems.

Next, KEA-BW supports the engineering companies that work for the cities. We expect that few big cities have the capacity to perform the planning process with their own municipal staff. The majority needs the support of an experienced engineering company.

The next step for KEA-BW is to develop a technical handbook defining boundary conditions for the task. Heat plans of different cities need to be comparable. Hence, the boundary conditions for calculations have to be identical. For example, interest rates or the availability of renewable gases and their price have to be defined.

We expect district heating to play a significantly more dominant role in the future. Excess heat, cogeneration, heat pumps, and solar thermal systems can be used much more efficiently if the systems exceed the demand of a single building. Thus, municipal heat planning will pave the road towards new and more efficient district heating systems.

For further information, please contact Volker Kienzlen, volker.kienzlen@kea-bw.de