The Netherlands has launched its first national standard for calculating heating costs: the Warmterichtlijn. Modelled on Denmark’s Samfundsøkonomiske method¹, it makes heat planning more consistent, more comparable, and more credible. It could transform how district heating decisions are made — in the Netherlands, and far beyond.
By Jacob Janssen, Energy Economist, TNO and Marten Witkamp, Energy consultant, Wattopia
Published in Hot Cool, edition no. 4/2026 | ISSN 0904 9681 |
When heat planning lacks a common language
Municipalities across the Netherlands are making some of the most consequential infrastructure decisions in generations. They are deciding which neighbourhoods should get district heating, which should get heat pumps, and which should wait for something better.
These decisions involve billions of euros and will shape heating infrastructure for decades. Yet, until recently, the calculations underpinning these choices were done differently in every city and by every consultant, using different assumptions.
The result? Numbers that could not be compared. Decisions that were hard to justify. And trust that was difficult to build – with residents, with regulators, and with investors.
“Good and comparable cost calculations are essential to properly underpin these choices. In practice, however, such calculations are often carried out in different ways, which makes transparency and comparability difficult.”²
The Warmterichtlijn — the Dutch Heat Calculation Guideline — was developed to solve exactly this problem. And to do it well, the Netherlands looked north to Denmark.
What is the Warmterichtlijn?
The Warmterichtlijn is a national set of principles for calculating the costs of sustainable heating solutions for homes and other real estate in the Netherlands. It was published by the NPLW—the National Program for Local Heat Transition—and Nieuwe Warmte Nu—a program to support district heating projects—and is designed for use by municipalities, engineers, and consultants.
It covers both collective solutions (such as district heating networks) and individual solutions (such as heat pumps). It applies at different stages of the planning process, from early-stage exploration to detailed project development.
What the Warmterichtlijn covers
✓ Increased consistency and transparency for cost calculation for all sustainable heating options
✓ Applicable to both collective (district heating) and individual solutions
✓ Usable at every phase of the planning process
✓ Includes guidance on key assumptions: energy prices, discount rates, lifetimes
✓ Freely available for download via the NPLW and NWN websites
The core logic is simple: if every party uses the same method and the same base assumptions, then the outputs become comparable and understandable. A district heating study in Rotterdam can be weighed against one in Groningen. A consultant’s analysis in 2025 can be compared with one from 2027. The numbers mean the same thing or, if they don’t, the differences be can more easily identified.
What this means for heat planning
The Warmterichtlijn is not just a methodological tidying exercise. It has real, practical consequences for how heating projects develop, and for how fast.
More credible decisions
When calculations are consistent, they are easier to scrutinise. Regulators, politicians, and residents can challenge assumptions rather than methods. This builds legitimacy for heating projects and reduces the risk of decisions being reversed late in the process.
Better comparisons
Municipalities can now compare district heating against heat pump solutions on a like-for-like basis. The Warmterichtlijn provides a common language. That means better decisions about which solution fits which neighbourhood and more efficient use of public funds.
Faster planning
Without a standard method, every project starts from scratch. Consultants reinvent the wheel. Municipal staff must evaluate incompatible studies. With the Warmterichtlijn, the starting point is standardised. Teams can focus on the substance, not the structure. This accelerates the planning cycle.
A stronger foundation for investment
Investors in district heating need confidence that projects have been rigorously assessed. A nationally recognised calculation standard signals that the work has been done properly. This helps projects reach financial close more quickly and with lower financing costs.
Opportunities for better oversight
The Dutch regulator, the ACM (Authority for Consumers and Markets), oversees district heating tariffs and approves project proposals. When all projects use the same transparent calculation standard, oversight tasks automatically shift to the public. The regulator no longer has to check each system, but can focus on the cases where there are complaints or significant discrepancies between planned costs and tariff outcomes.
The Danish Blueprint: Samfundsøkonomiske Analysis
The Warmterichtlijn did not emerge from nothing. Its design was explicitly inspired by Denmark’s long-established approach to energy planning: the Samfundsøkonomiske method.
Samfundsøkonomiske means ‘socio-economic’ in Danish. It refers to a method of cost-benefit analysis that evaluates energy projects from a whole-of-society perspective, not just the perspective of a single company or household.
The Danish Energy Agency has maintained and updated this method for decades. It underpins Denmark’s regulatory framework for district heating. Before a district heating project can be approved, it must demonstrate a positive outcome in a Samfundsøkonomiske analysis³.
The Danish Samfundsøkonomiske: Key Features
✓ Long-standing national standard, maintained by the Danish Energy Agency
✓ Regularly updated — most recently with 2025 assumptions (published March 2026)
✓ Used for all district heating project approvals under Danish heat supply law
✓ Evaluates costs from a whole-of-society perspective
✓ Includes standardised energy price forecasts, CO₂ values, and discount rates
✓ Publicly available — full methodology and spreadsheets downloadable
Denmark’s district heating sector is often cited as one of the most advanced in the world. Around 65% of Danish homes are connected to district heating networks — one of the highest penetration rates globally. This did not happen by accident. It happened because the regulatory and analytical framework made good projects easy to approve and bad projects easy to reject.
What the Netherlands learned — and adapted
The Dutch approach drew directly on Danish practice, but it did not copy it.
The Samfundsøkonomiske method is embedded in a regulatory system that is specific to Denmark, including Danish heat supply law, Danish tariff regulation, and Danish local government structures. Translating it to the Netherlands required adaptation.
The Warmterichtlijn takes the core insight: consistent, transparent, society-wide cost assessment — and fits it to the Dutch context. This means the Dutch planning system, Dutch subsidy structures, and the Dutch mix of collective and individual solutions.
From regulation to guideline
In Denmark, the Samfundsøkonomiske method is legally required. In the Netherlands, the Warmterichtlijn starts as a guideline, a best practice standard that municipalities and consultants are encouraged to adopt.
Covering individual solutions too
One important Dutch adaptation is the scope. The Warmterichtlijn explicitly covers individual heating solutions — such as heat pumps — alongside collective district heating. This reflects the Dutch reality, where individual solutions remain a major part of the transition, especially in lower-density areas.
Why more countries need their own standard
The Netherlands is not alone in struggling with inconsistent heat planning calculations. Across Europe, countries face the same problem: heating options are evaluated using different assumptions and untransparent modelling. As a result, good projects stall, bad projects advance, and policymakers cannot learn from one project to the next.
The EU in its Energy Efficiency Directive (Article 25) requires all member states to carry out comprehensive heating and cooling assessments using cost-benefit analysis, and to promote local heating and cooling plans in municipalities with more than 45,000 inhabitants. But it does not prescribe how those calculations are done. Each country, or even each heating project, defines its own methodology.
The European Union has been pushing for greater consistency in energy planning through the Energy Efficiency Directive. A common analytical framework for heating costs would make these directives far easier to implement. Both the Warmterichtlijn and the Samfundsøkonomiske are available freely to policymakers and researchers in other EU countries to learn from and adapt to their local context.
Call to action for heating professionals
For heating professionals, the Warmterichtlijn is both an opportunity and a call to action.
It is an opportunity because it creates a common language. Consultants who master the methodology will be better placed to advise municipalities, challenge poor analyses, and win the trust of decision-makers.
It is a call to action because standardisation works only if it is widely adopted. The guideline exists — but its power multiplies with every firm and every municipality that uses it.
Engineers, consultants and planners can download the Warmterichtlijn from the NPLW and NWN websites and study the methodology. They can align their firm’s standard calculation models with the guideline’s assumptions. They can review the Danish Samfundsøkonomiske method for deeper methodological context, advocate for its adoption in municipal procurement and tendering specifications, and share best practices with peers – including internationally.
Footnotes:
¹ Samfundsøkonomiske means ‘socio-economic’ in Danish and has slowly become a term for district heating projects. It refers to a cost-benefit analysis method that evaluates energy projects from a whole-of-society perspective—not just the perspective of a single company or household.
² https://nwn.nu/kennis/de-warmterichtlijn/
³ As researcher Sanne Akerboom noted in a 2024 study of Dutch heat transition policy, Danish municipalities carry out social and cost-benefit analyses to assess impacts on energy prices, jobs, and the potential of different energy resources — providing a holistic basis for decisions that the Netherlands has lacked. (Source: Akerboom, S. (2024). Urban heat transitions policy. Heliyon, 10(19). doi:10.1016/j.heliyon.2024.e37932)
For more information, please contact: jacob.janssen@tno.nl or marten@wattopia.nl