Consortium of Dutch Technology Innovators Launches WarmteFlex: Making Smart Heat Control a Reality for Dutch Households
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This project is co-financed by Top Sector Energy from the Ministry of Climate and Green Growth.
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The Challenge
Heating represents 75% of household energy consumption in the Netherlands, making it a critical factor in the energy transition. With 1.5 million heat pumps expected to be installed by 2030, these systems are essential for decarbonizing home heating. However, this rapid adoption creates significant challenges: heat pumps can account for up to 50% of a household's electricity consumption and place considerable stress on an already strained electrical grid.

Currently, most heat pumps operate with very limited steering capabilities—often just basic "Smart Grid Ready" functionality that offers minimal flexibility. This means households cannot optimize their heating based on their own solar production, take advantage of dynamic energy tariffs, or respond to grid capacity constraints.
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The Solution: WarmteFlex
Today, a consortium of leading technology innovators officially launches WarmteFlex, an ambitious collaboration aimed at developing truly interoperable home energy systems. TNO, together with industry partners Intergas, Plugwise (Anna Technology B.V.), Currentt, and the OpenTherm Association, is creating a comprehensive solution where energy management systems (EMS), heat pumps, and thermostats work seamlessly together using open standards.
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At the heart of WarmteFlex are two key open standards: S2 (Smart Energy Services) and OpenTherm. By integrating these protocols, we enable local, intelligent decision-making that doesn't rely on cloud connectivity, ensuring both reliability and user privacy.
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What We're Building
The WarmteFlex project encompasses several critical components:
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Resource Managers: We're developing sophisticated resource management capabilities for both heat pumps and thermostats, enabling them to communicate their flexibility potential and respond intelligently to optimization signals.
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Flex Home Model: Each home has unique thermal characteristics and flexibility potential. We're creating a model that understands these individual behaviors, allowing the system to predict and optimize heating patterns while maintaining comfort.
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‍Local EMS Control: The energy management system provides real-time control logic and user interaction, serving as the orchestration layer that coordinates all home energy assets. The local EMS optimizes across the complete home energy system—balancing solar energy production, dynamic electricity tariffs, grid conditions, battery storage, EV charging, and heat pump operation to minimize costs while maintaining comfort and supporting grid stability.
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S2 Integration: By embedding the S2 protocol directly in the EMS, we enable autonomous, local decision-making that can respond in real-time to household needs, energy availability, and grid conditions.
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Field Testing: Real-world validation is essential. We'll conduct comprehensive field tests to validate both system performance and user experience, ensuring our solution works reliably in diverse home environments.
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Open Documentation: To accelerate industry adoption and drive standardization, all technical documentation and learnings will be published openly, enabling other manufacturers and system integrators to implement compatible solutions.

‍The Impact
WarmteFlex will deliver tangible benefits for households, the energy system, and the broader transition to sustainable energy:
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For Households:‍

• Lower energy costs through intelligent optimization that leverages own solar production, responds to dynamic electricity tariffs, and prepares for future variable grid tariffs
• Maintained comfort through local control systems that prioritize user preferences and thermal comfort
• Future-proof technology based on open standards that ensure long-term compatibility and avoid vendor lock-in

For the Grid:

• Reduced congestion by intelligently balancing heat pump loads within available capacity limits
• Enhanced stability through demand flexibility that can respond to grid conditions
• Deferred infrastructure investments by optimizing use of existing grid capacity

For the Energy Transition:

• Accelerated heat pump adoption by making implementation feasible even in capacity-constrained areas where grid upgrades would otherwise be required
• Scalable solution with 1.5 million heat pumps expected by 2030, the flexibility potential is enormous
• Industry standardization through open documentation that enables broad adoption beyond project partners

A Collaborative Approach
WarmteFlex brings together expertise across the entire value chain:

• TNO provides system integration expertise, S2 deep expertise, and research capabilities
• Intergas contributes heat pump knowledge and innovation, building heat modeling, and implementation experience
• Plugwise brings thermostat and home automation expertise
• Currentt provides EMS expertise, hardware & software capabilities for connecting all devices, smart steering, local orchestration optimization, and dashboarding insights
• OpenTherm Association ensures standardization and protocol compatibility, scalability

This diverse partnership ensures that the solutions we develop are not only technically sound but also practical to implement and beneficial across all stakeholder groups.
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Looking Ahead
The WarmteFlex project represents a critical step toward truly smart, flexible home energy systems. By prioritizing interoperability, open standards, and local control, we're creating a foundation that can scale across the Netherlands and beyond.
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As the energy transition accelerates and heat pumps become the standard for home heating, solutions like WarmteFlex will be essential to ensure this transition is affordable for households, manageable for the grid, and sustainable for our climate goals.
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We invite other organizations working on interoperable home energy systems, policymakers interested in enabling the energy transition, and stakeholders across the heating and energy sectors to follow our progress and engage with our findings.

‍About the Partners
TNO is an independent research organization in the Netherlands that connects people and knowledge to create innovations that boost the competitive strength of industry and the well-being of society in a sustainable way.
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Intergas is a leading manufacturer of high-efficiency central heating boilers and heat pumps, committed to sustainable heating solutions.
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Plugwise develops smart thermostats and energy management solutions that give users control over their home energy consumption.
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Currentt develops and produces local energy management systems in the Netherlands that optimize energy use across multiple devices and energy sources.
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The OpenTherm Association is an international organization that maintains and promotes the OpenTherm communication protocol for heating systems.