Municipal heat planning: what the 30 June 2026 deadline means for large cities

What applies to large cities by 30 June 2026

By 30 June 2026, all 84 German cities with more than 100,000 inhabitants had to have a municipal heat plan, the kommunaler Wärmeplan, in place; smaller municipalities have until 30 June 2028. The basis is the Heat Planning Act, the Wärmeplanungsgesetz (WPG), whose full name is the Act on Heat Planning and the Decarbonisation of Heat Networks. It has been in force since 1 January 2024 and creates, for the first time, a nationwide obligation to plan the heat supply across the whole country.

The plan answers a single strategic question: how the heat supply of each district is to become climate-neutral by 2045 at the latest. It is not a one-off study but a structured planning process whose result, the zoning of the city into prospective heat supply areas, is the foundation on which utilities, building owners and the municipality itself can take their next decisions. About 10,700 municipalities are covered in total, which makes this one of the largest planning exercises the heat transition demands.

The two-stage deadline reflects capacity rather than ambition. Large cities have more administrative resources and denser networks, so they went first, by 30 June 2026; the much larger number of smaller municipalities follows by 30 June 2028. The deadline was also meant to be the moment from which the Building Energy Act starts to bite in a given city; the legislator deleted that link in July 2026, as set out further below. For a utility, this is the point at which the strategic picture of where heat networks make sense, and where they do not, finally has a legal footing.

The four steps of heat planning

The heat plan is produced according to a method laid down in the WPG, so it is not a free-form report but a structured, data-driven process with defined intermediate results that the responsible planning body has to publish. Four steps build on one another: a suitability check, an inventory analysis, a potential analysis and a target scenario that leads into the zoning of the area and an implementation strategy.

The first step is the suitability check (section 14 WPG). This is a rough pre-screening of which sub-areas are ruled out for a heat or hydrogen network from the very start, for example because they are too thinly built up or too far from any feasible network. Those sub-areas are then planned as decentralised through a shortened procedure, which spares the municipality from running the full analysis where the answer is already clear. The second step, the inventory analysis, records the present heat demand, the supply structure and the greenhouse-gas emissions for each sub-area, so the plan starts from a factual picture of how the city is heated today.

The third step, the potential analysis, looks forward: it maps the locally available renewable heat and the unavoidable waste heat, together with the storage and saving potential of each sub-area. This is where the question of which renewable sources a district could realistically draw on is answered. The fourth step brings the strands together in a target scenario, which is then translated into the zoning of the city into prospective heat supply areas and into an implementation strategy with concrete measures and a timeline.

Each of these steps produces an intermediate result that has to be made transparent, which is what turns heat planning from an internal exercise into a shared planning basis. The figure below shows the three specialists at the centre of that work, reviewing the colour-coded heat map and the city plan that the inventory and potential analyses feed into.

District-heating, review, decentralised: what the zoning means

The core result for utilities is the zoning of the city area into prospective heat supply areas. The WPG knows four categories, and they effectively decide the supply logic of a whole district. A district-heating area (section 3 no. 18) is one where a heat network exists or is planned and a significant share of final consumers is to be supplied through it, so this is the Fernwärme, the district heating, that carries the heaviest investment. A hydrogen network area (section 3 no. 23) provides supply through a hydrogen network and is the exception in practice.

The other two categories cover the rest of the map. An area for decentralised heat supply (section 3 no. 6) is one that is predominantly not supplied through a heat or gas network, so it relies on individual heating systems such as heat pumps. An area under review (section 3 no. 10) is still open, because the facts needed to decide are not yet sufficiently known, and it is the category that keeps a planning option alive where the analysis cannot yet settle the answer.

The single most important point about this zoning is what it does not do. The zoning is a forecast, not a connection obligation and not a building requirement. The heat plan is explicitly a legally non-binding, strategic specialist plan under section 3 no. 20 WPG, so the assignment of a district to one category or another does not by itself oblige any owner to connect to a network or to change a heating system. A separate area designation under section 26 WPG, a distinct legal act that the municipality has to take deliberately, does not oblige owners either; under section 27 WPG it feeds into land-use plans and other public planning. For a district-heating area, the climate-neutral generation that then follows, the large heat pumps and power-to-heat plants that supply the network, is a separate topic, covered in the analysis of power-to-heat and large heat pumps for district heating.

The deleted link to the Building Energy Act

Until late July 2026 the heat plan was tied to heating law. Under section 71(8) of the Building Energy Act, the Gebäudeenergiegesetz (GEG), the 65-percent-renewables rule for newly installed heating systems in existing buildings was to apply in large cities over 100,000 inhabitants after 30 June 2026 and in smaller municipalities after 30 June 2028. A municipality could bring the rule forward through an advance area designation under section 26 WPG, in which case it applied one month after the decision was published. The planning deadline would have become the heating-law deadline as well.

That did not happen. In late June 2026 the legislator moved the large-city date to 31 October 2026 (Article 8 of the Act of 22 June 2026, BGBl. 2026 I No. 191). Four weeks later it deleted sections 71 to 73 altogether: Article 1 no. 32 of the Act of 23 July 2026, BGBl. 2026 I No. 226, has applied since 29 July 2026. Since then the act has been called the Gebäudemodernisierungsgesetz (GModG). So the 30 June 2026 deadline never triggered the 65-percent rule in the large cities.

What applies now? Section 42 GModG lists ten options for replacing a heating system, among them a heat pump, a connection to a heat network and a gas boiler; sections 43 to 46 set conditions for some of them. Owners who install a gas, oil or LPG heating system in an existing building after 29 July 2026 must ensure that at least 10 percent of its heat comes from biomethane, bio-oil, biogenic LPG or hydrogen from 2029, 15 percent from 2030, 30 percent from 2035 and 60 percent from 2040 (section 43 GModG). Nowhere does the act refer to the heat plan any more.

References to the GEG were removed from the Heat Planning Act as well (Article 8(10) of the same Act). An area designation under section 26 WPG therefore no longer triggers any heating obligation; under section 27(2) WPG it only has to be taken into account in land-use plans and other public planning. For owners the heat plan remains a guide to whether a heat network is likely in their district. Utilities now have to win connections to the heat network on price and offer rather than through heating law.

Status in June 2026 and funding

Shortly before the deadline, the large cities were on track to meet it. According to the Competence Centre for Municipal Heat Transition (KWW), whose head is Robert Brückmann, the large cities would deliver: six of the ten largest cities had adopted their plan or were in final public display, about 80 percent of mid-size municipalities and over half of small ones were already working on the plan or finished. Concrete adoptions illustrate the pace: Munich adopted its plan on 26 November 2025, Stuttgart as early as 2023, Essen on 25 March 2026 and Düsseldorf on 7 May 2026, while Hamburg, Frankfurt and Dortmund were in the final stretch in June 2026.

Baden-Württemberg was the front-runner, ahead of the federal law. Under its state climate act, the KlimaG BW, urban districts and large district towns there already had to plan by 31 December 2023, with 103 municipalities under obligation, so the south-west had completed a first round of municipal heat plans before the WPG deadline applied elsewhere. That head start is one reason several of the most advanced examples sit in that region.

The funding model changed with the WPG. Since the end of 2023, heat planning is no longer funded via the Kommunalrichtlinie, whose earlier 90-percent grant ended in mid-December 2023 when the WPG came into force. Instead, the federal government provides the Länder with EUR 500 m as a connexity settlement for the years 2024 to 2028, in five tranches of EUR 100 m each through a fixed value-added-tax amount, and the Länder pass the money on to the municipalities. The stakes behind all of this are large: nationwide about 14 percent of households are supplied by near- or district heating today, and the heat plans will decide how far that share grows.

What utilities should do now

For a utility, the heat plan is the entry ticket to any robust network-investment decision. The zoning into a district-heating area or a decentralised area defines the future business field and the order in which the build-out should happen, so the plan is not a compliance task for the municipality to handle alone but a shared data basis that will run through the heat planning data space, one that utilities should help shape and whose data quality they should secure. Treating it as someone else's paperwork is the most expensive mistake on offer.

The practical work starts with the data base. A utility should bring its heat-consumption figures, its network inventory and its load profiles into the process as a reliable foundation for the inventory and potential analyses, because the quality of the zoning is only as good as the data behind it. The second step is to prioritise build-out areas: from the zoning, derive a concrete sequence of districts and realistic connection-rate targets, so that the billions in network investment go first where the heat plan shows the strongest case.

The third step is to factor in the legal effect of an area designation. Since 29 July 2026 a designation under section 26 WPG no longer triggers any heating obligation for owners, but land-use and other public planning has to take it into account (section 27(2) WPG). It is worth checking where such a designation would secure a network build-out in planning terms, and where an area under review should deliberately stay open until the facts are clearer. The fourth step is citizen communication: making transparent early on which districts will be a heat network, an area under review or decentralised gives owners the planning certainty they need and reduces the friction that derails build-out later.

Beyond the plan itself, two adjacent processes deserve a place in the utility's roadmap. The day-to-day operation of a district-heating network, once built, is increasingly run with a digital twin and AI for utilities, and the heat plan also has to mesh with the gas distribution grids' transformation plan, which decides the parallel question of where the gas network is wound down. Both sit alongside the wider regulatory framework of the energy transition that shapes the economics of the build-out.

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