PAS 1878:2026

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What is PAS 1878:2026 Energy Smart Appliances – System Functionality and Architecture – Specification about?

PAS 1878:2026 supports the integration of energy smart appliances (ESAs) into a flexible, low-carbon energy system. It provides a technical specification that helps domestic appliances operate effectively within demand side response (DSR) frameworks, enabling consumers to manage their electricity demand more efficiently and reduce costs associated with energy consumption.

This PAS establishes a framework for individual ESAs to communicate with demand side response service providers (DSRSPs), transferring information about demand so that appliances can schedule operation when there is less pressure on the grid. It applies to individual appliances such as dishwashers, heat pumps, heating and hot water systems, EV chargers, and battery storage. It does not include requirements for home energy management systems, though these may be optionally incorporated into the architecture.

PAS 1878 was first published in 2021 and sponsored by BEIS. The 2026 revision was sponsored by Department for Energy Security and Net Zero. This 2026 revision should be understood as a response to stakeholder input and feedback, together with significant industry maturation, rather than as a simple update to a static specification. PAS 1878 was due for a substantial rethink rather than a light-touch update – this work began in 2023 following structured feedback exercises including the Interoperable Demand Side Response programme and sustained informal industry discussion.

By enabling consumer‑led flexibility through smart appliances, PAS 1878 plays a vital role in supporting the UK’s transition to a low‑carbon energy system.

Who is PAS 1878:2026 Energy Smart Appliances – System Functionality and Architecture – Specification for?

PAS 1878:2026 is primarily intended for manufacturers of energy smart appliances and customer energy managers (CEMs). It provides the technical foundation needed to design, develop and deploy ESAs and CEMs that can participate in demand side response services.

The PAS supports:

• energy smart appliance manufacturers (heat pumps, EV chargepoints, batteries, wet and cold appliances, HVAC systems);
• customer energy manager developers and home energy platform providers;
• DSR service providers and flexibility aggregators;
• maintainers of ESAs and interfacing products;
• software developers and service providers;
• network operators and system operators; and
• government and regulators (DESNZ, Ofgem).

Whether you're developing smart appliances or operating flexibility services, PAS 1878 provides the common technical framework needed to support interoperability, security, and effective participation in demand side response.

What does PAS 1878:2026 Energy Smart Appliances – System Functionality and Architecture – Specification cover?

PAS 1878:2026 specifies the technical requirements that enable energy smart appliances to participate effectively in demand side response within domestic and small business premises. It defines the on‑premises and cloud‑based system architectures in which energy smart appliances, Customer Energy Managers (CEMs) and DSR service providers interact.

The PAS addresses:

• Minimum requirements and specification for Interface A (the interoperable interface between CEM and DSRSP), including cybersecurity requirements.
• High-level information model and cybersecurity requirements for Interface B (the interface between CEM and ESA).
• Functional and cybersecurity requirements for ESAs and CEMs that enable DSR-based activities.
• Sequence of DSR-based activities including registration, commissioning, creation of DSR offers, offer selection, and device deregistration.

The specification supports compatibility with smart meter technologies and the GB smart metering system, compatibility with DSR services requested by transmission and distribution system operators, and compatibility with DSR services using variable electricity tariffs. It applies to cold appliances, wet appliances, HVAC appliances, smart EV charge points, and battery storage used in domestic or small business settings.

PAS 1878 does not cover the operational aspects of DSRSPs, contracting or payment services, or demand side response services where a DSRSP directly controls devices by generating and setting power profiles.

Why should you use PAS 1878:2026 Energy Smart Appliances – System Functionality and Architecture – Specification?

PAS 1878 provides the technical interoperability layer that allows this flexibility to operate securely and at scale by enabling energy smart appliances and customer energy managers to participate effectively in demand side response.

Using PAS 1878:2026 supports organizations to:

• Design ESAs and CEMs that can participate reliably in DSR services, supporting grid stability and enabling consumers to reduce energy costs.
• Ensure technical interoperability across different manufacturers, platforms and service providers.
• Meet cybersecurity expectations through an outcomes-based approach that accommodates new methods and technologies.
• Benefit from a specification that has been developed with extensive industry input including DESNZ, NCSC, National Energy System Operator (NESO), Ofgem, major manufacturers, and service providers.

The PAS has been designed to be less restrictive than previous approaches. It allows for flexibility in implementation while maintaining the security and interoperability needed for effective demand side response at domestic scale.

What has changed?

PAS 1878:2026 represents a significant evolution from the first edition launched in 2021. The revision has been substantially restructured to improve clarity and readability, with new content incorporated based on feedback from the Steering Group, public consultation, the DESNZ Interoperable Demand Side Response Programme and Edition 1 development feedback.

Key updates include:

• Outcomes-based approach: This has been adopted in areas such as communications and cybersecurity requirements. It allows the PAS to be less restrictive and to accommodate upcoming new methods and technologies, while still maintaining security and interoperability.
• Improved architecture flexibility: The concept of the Smart Energy Processing Function has been introduced as a logical function that may be implemented either integrated with an ESA, as a separate device, or in the cloud. The CEM can now explicitly connect to multiple ESAs and aggregate them, with the information model updated to support this.
• Enhanced operational control: A new messaging framework enables DSRSPs to send Flexibility Performance Requests (FPRs) to ESAs, allowing them to request flexibility offers defined by power limits over time. The introduction of this framework is significant as it is designed to be extensible — additional payloads or types of performance requests can be incorporated in the future to support evolving flexibility and grid service needs. This approach gives service providers greater control over flexibility procurement and enables ESAs to respond with a smaller number of more targeted, and therefore more efficient, flexibility offers.
• Modernized Interface A: OpenADR 2.0b has been replaced with OpenADR 3.1, and the normative Annex has been entirely rewritten with practical examples of code. The implementation follows standard OpenADR practice and has been reviewed by an OpenADR 3.1 expert.
• Extensibility: A new approach to Interface A versioning has been adopted, which allows the PAS to accommodate updates and modifications within the existing structure. This framework supports multiple versions of Interface A and the use of companion profiles, enabling the specification to evolve without requiring fundamental restructuring.
• Simplified cybersecurity: The cybersecurity clause has been significantly simplified by removing detailed prescriptive requirements in favour of outcomes-based guidance that references international standards and industry best practice.

These updates ensure PAS 1878 remains aligned with how the sector is operating and where it is heading. It supports the technical foundation for smart, secure, interoperable flexibility at domestic scale.