by Linda Bertelsen
output center source

Municipalities in Flanders and Belgium are starting to implement sustainable district
heating, and they can use a three-step methodology in this starting phase:

Let’s meet: The energy broker
Let’s plan and map: Heat zoning plans and maps
Let’s calculate and design the optimal trajectory at a municipality scale:
Pathway optimization

By Esther Biermans, Energy Broker, Province of Antwerp,
Glenn Reynders, R&D Professional Sustainable Urban Development
and Robbe Salenbien, Senior Researcher, PhD

Energy broker

A large proportion of our total energy consumption is used for heat, both for industry and for domestic heating. We currently use fossil fuels almost exclusively for this purpose and making heat more sustainable is essential for the transition to a low-carbon energy system. The great challenge here is to bring providers and consumers of heat into contact with each other.

And there is often still a prior step missing: making companies aware of the potential of available (residual) heat that they can supply to consumers.

To facilitate this energy exchange, energy brokers can be brought in. The energy broker is a public broker who connects (residual) energy from companies to potential energy customers. It is a methodology developed in the Interreg-DOEN project (Sustainable Development Energy Neutrality) in Flanders and the Netherlands, from 2018 to 2021. The Interreg-DOEN project has now come to an end, but many Flemish and Dutch partners continue to take on the role of energy broker. A follow-up project and the platform for the energy broker (https:// www.platformenergiemakelaar.be/) are now being developed.

The platform is an online community on which energy brokers can exchange knowledge and experiences and offer training to
new partners who want to offer themselves as energy brokers. Residual heat from companies can be exchanged with other companies, public buildings, or even private partners. For local authorities, it is not always easy to make this jigsaw puzzle of heat supply and demand fit together. From the very beginning, the independent energy broker acts as a liaison between the various partners in a joint energy project such as a district heating network.

For public authorities, the energy broker can therefore, together with all stakeholders, focus on the objectives of the project and establish the link between supply and demand. What are the possibilities? Who are the right partners? How will the district heating network become workable in the long term? All these questions are taken into account by the energy broker to make the project a success. Once the right partners are in contact, the objectives are defined and the project has gotten off to a good start, the energy broker can take a step back and leave the actual elaboration of the project to the project partners.

Heat zoning plan, heat policy plan, heat vision, heat zoning maps

Cities and municipalities are thinking hard about how they can help achieve European, national and regional climate ambitions locally. One of the issues here is how buildings will be heated in the future. In order to realize a well-considered energy transition, heat zoning plans are a particularly useful instrument. A heat zoning plan maps out a vision for the future by indicating for the territory of a municipality in which neighbourhoods and streets sustainable heat can be supplied via a heat network in the future, or where sustainable heat will be produced at individual building level. Ideally, such a heat zoning plan goes together with a heat policy plan – which includes the policy steps to realize the heat zoning plan – and is based on a thorough local heat vision and analysis of the local context.

Because a heat zoning plan aims to provide all stakeholders – from local residents and companies to investors and policy makers – with guidance in making their own energy choices, one of the major challenges is to draw up broadly supported heat zoning plans that reflect climate ambitions taking into account local social, demographic and economic interests.

Nevertheless, the starting point in the heat zoning process typically lies in mapping the current heat demand, estimating different scenarios about the evolution of that heat demand and making an inventory of potential sustainable sources for
meeting the heat (and cold) demand. Using extensive data analyses and simulations, this knowledge is brought together
in heat zoning maps.

The heat zoning maps are then an interesting tool for various parties such as policy makers, but also energy brokers from cities and municipalities. They enable them to weigh up possible policy choices – which take into account socio-demographic
factors in addition to techno-economic factors. But perhaps even more importantly, we see that in practice they mainly make it possible to identify opportunities – e.g. for 5th generation heat networks – to be identified at an early stage.

Pathway optimization

By identifying such an opportunity, one is already one step closer to realizing a sustainable energy system. However, determining a design that meets all geographic and techno-economic requirements is a complex puzzle with many degrees
of freedom, each of which can have a major impact on the feasibility of a project. Many interdependent choices have to be made; which of the mapped sources are linked to which users, via which pipeline route and at which temperature level, at what cost, …
Completing such a puzzle has long ceased to be possible manually, and although designers have been using software that supports them for a long time to work out known networks in more detail, until recently there was no tool available that quickly and without simplification was able to determine the optimal design given all the preconditions contained in a heat zoning map.

An initiative that can change this is PathOpt, a non-linear optimization environment that determines an optimal network topology for geographically defined zones with known heat demand and possible sources. The non-linear aspect allows to calculate the physical behaviour of such a network without simplifying, while the optimization techniques used guarantee a fast performance. Both aspects together make it possible to calculate all kinds of scenarios in very short periods of time, and these form a crucial extra piece of information for the users of heat zoning maps.


Successfully and sustainably developing a new district heating project can be a daunting task, as so many actors and information streams need to come together. Here, a three-step approach was presented that provides a structured workflow.

An energy broker helps in the earliest phases, bringing together customers and providers, who often are unaware of the role they could play. With the support of heat zoning maps, they can then zoom in on specific geographical regions that show great potential in term of social, demographic, and economic interest. Finally, software environments bring in the computational power to quickly assess specific scenarios in the selected zones, so that all involved partners can select and weigh different options in the earliest stage of development and limit the amount of uncertainty involved.

For further information please contact: Erik De Schutter, erik.deschutter@vito.be

“How to start with sustainable district heating: A Flanders/Belgian approach” was published in Hot Cool, edition no. 4/2022
How to start with sustainable district heating - A Flanders-Belgian municipality approach, article in Hot Cool no. 4, 2022
Download and print the article here

Meet the authors

Glenn Reynders
R&D Professional Sustainable Urban Development
Esther Biermans
Energy Broker, Province of Antwerp
Robbe Salenbien
Researcher Thermal Energy Technologies