Flanders’ Warmest City: How Mechelen is getting everyone on board to deliver healthy heat

With a population of 87.000 inhabitants, Mechelen is the 5^th biggest city in Flanders (Belgium), and it prides itself in being the warmest, concentrating efforts in harnessing all of the potential of local and renewable sources of heat to deliver affordable and healthy heat to every home.  

It all starts with a plan 

Buildings in Mechelen still heavily depend on fossil fuels for heating, with approximately 35.000 connections to the gas grid. Mechelen has the ambition to decarbonise all buildings by 2050, making a heat detox necessary. In this context, the city adopted its municipal heat plan in 2024. This plan commits to four pillars: (1) Heat planning (2) District heating (3) Building decarbonisation and (4) the  Heat Coalition. Five guiding principles were also identified: (1) Affordable heat & just transition (2) Alliances & co-creation (3) Sustainable & reliable heat (4) Green jobs & skills (5) Local community benefits. 

The municipal heat plan contributes to many of the strategic objectives of Mechelen’s Sustainable Energy and Climate Action Plan (SECAP), adopted in 2020. Starting from 2030, more than 1.400 buildings will need to switch to fossil-free heating alternatives each year in order to fully decarbonise its building stock. This means that a heat demand reduction of 50% by 2050 has to be achieved. Furthermore, heat supply with individual heat pump installations will cover 50 to 60% of heat demand in 2050, while heat supply with district heating shall cover 40 to 50% of heat demand in 2050. The share of renewable heat sources in heat networks will be of at least 85% in 2030 and 100% in 2050. 

District heating: from a distant dream to a successful reality 

For a long time, it was assumed that heat networks were simply not possible in Mechelen, as there is no dominant residual heat source such as a waste incineration or power plant. Moreover, heat network projects are complex, due to long lead times and a multitude of stakeholders. However, emerging pilot projects and recent heat potential and zoning maps indicate otherwise. Three particular areas of interest have been identified: 

• Industrial areas are interesting areas for heat networks due to the presence of both large heat consumers and waste heat sources, with the potential for green renewable industrial transition hotspots. In the industrial areas Mechelen-North and Mechelen-South there are opportunities to valorise waste heat from sewage water plants, data centres and industrial processes.
• The existing buildings in the historical centre and the city districts around it are a promising area for a heat network because of the high heat density and residential apartment buildings as heat consumers. Moreover, the transformation of the two-way ringroad to a one-way public space offers a unique momentum to combine with heat infrastructure.
• Large-scale urban renewal projects with high sustainability ambitions can act as true leverage for innovation. In Keerdok, a 5th generation heat network with energy recovered from sewage system and stored in geothermal borehole fields will provide heating and cooling to approximately 250 dwellings. In Ragheno, a similar concept is explored but for more than 2.500 dwelling units and >100.000 m² office area that will be realised in the coming ten years. 

In sum, the city of Mechelen believes that the large-scale roll-out of heat networks combined with heat storage is part of the solution to provide green heat to densely built-up areas in Mechelen, while maximising the potential of local, renewable and residual heat sources. 

The Heat Coalition 

As part of the municipal heat plan, Mechelen established a multi-level and multi-sectoral partnership, the Heat Coalition. It is a local green deal in Mechelen between government, businesses and civil society. More than 25 organisations signed the charter of the Heat Coalition in April 2024, including key players such as district system operators, energy cooperatives, higher government bodies, vulnerable household support organisations, social housing corporations, knowledge centres, local businesses etc. Membership is open and it is still possible to join the Heat Coalition, as long as there is willingness to engage in the city’s heat plan. 

As the Heat Coalition forms the governance structure needed to implement the heat plan, taskforces are created (at least one for each pillar of the heat plan). Each taskforce consists of a balanced mix of local stakeholders, political decision-makers and different departments of the city administration to coordinate and implement actions from the city’s heat plan. A transition team monitors if all actions are in-line with the heat transition vision as outlined in the heat plan and initiates a reflexive learning process to identify bottlenecks and breakthroughs. The core-team is the steering group of the Heat Coalition, with 2 representatives from each taskforce and transition team. Finally, the community of the Heat Coalition communicates and organises networking opportunities and learning events, this way reaching out with activities and results to a broader audience. 

The Heat Coalition is the result of a ‘heat transition arena’ that was organised between February and March 2023. This was a series of three co-creation workshops in which city administration and policy-makers together with 20 local stakeholders and experts reflected on activities and results done in the framework of the heat plan, composing a transition vision and action plan. This formed the basis of the municipal heat plan and the Heat Coalition. 

Responding to everyone’s needs 

In the municipal heat plan, ‘affordability and tackling energy poverty’ is one of the five guiding principles, and social organisations are involved in the Heat Coalition. Four initiatives done by the city of Mechelen in collaboration with Heat Coalition members and other stakeholders demonstrate that project activities respond to the needs of vulnerable households: 

• First, Mechelen’s Home Integrated Renovation Service organised the ‘Check your boiler campaign’, offering inspection and maintenance free of charge to vulnerable households in Mechelen. This ensures proper and safe operation of the boiler and at the same time up to 8% energy savings. The City cooperated for this project with local stakeholders and social services of 10 municipalities in the surrounding region.
• Second, a neighbourhood approach to renovation is applied. A key case is the neighbourhood renovation of Nekkerspoel, targeting approximately 450 dwellings with a higher share of vulnerable households compared to other neighbourhoods. It demonstrated the ability to activate within 6 months green investments for 8% of the dwellings, and the appetite from private contractors to engage in a framework contract as neighbourhood contractor.
• Third, Mechelen specifically targets co-owned condominiums with its integrated home renovation service. This building typology has a higher share of vulnerable households in co-owned condominiums compared to single-family homes (less expensive, more rental, smaller homes). At the same time, barriers for energy renovation are higher caused by the co-ownership, technical complexity and high financial investments needed.
• Finally, the city also experiments with setting-up energy communities with social housing tenants. A key pilot is the social neighbourhood Otterbeek, in which social housing corporation Woonland, local energy cooperative Klimaan and City of Mechelen, have been experimenting with a local energy community between social housing tenants. 

Where Mechelen is in its heat strategy

Mechelen's Heat Detox

Key heat figures:

• Emissions related to heating: 46%
• 225.864 tonnes of CO2 coming from buildings (mainly from heating)
• Km of DHC planned: 0.33
• Percentage of renewables in heating system: Existing homes: 1,9%; New homes: 35% 

Covenant figures:

• Signatory to the Covenant of Mayors since: 2012
• Emission reduction ambitions:  
  • Overall CO2 emission reduction target: 171 ktonnes CO2 by 2030
  • % GHG emissions reductions by 2030: -40%
  • % GHG emissions reductions by 2050:-80%