Extending the SAREF4ENER Ontology with Flexibility Based on FlexOffers

TL;DR

The paper tackles the scalability gap of exact energy-flexibility models by extending the industry-standard SAREF4ENER ontology with the dCO module to support the full FlexOffer model, including advanced constraints (DFO) and uncertainty (UFO) while preserving backward compatibility. It introduces a detailed ontological design, constraints encoding (including H-representation for DFO and polynomial representations for UFO), and FO messaging for interoperability with WoT, CIM, and EEBus. Real-world demonstrations across multiple countries validate interoperability and show dCO’s superior flexibility representation and device coverage (batteries, EVs, heat pumps) compared to SAREF4ENER, along with scalable optimization and aggregation. The work enables more accurate, scalable, and interoperable flexibility services for smart buildings and energy systems, with future work planned to extend FO features and maintain compatibility as FlexOffer standards evolve.

Abstract

A key element to support the increased amounts of renewable energy in the energy system is flexibility, i.e., the possibility of changing energy loads in time and amount. Many flexibility models have been designed; however, exact models fail to scale for long time horizons or many devices. Because of this, the FlexOffers model has been designed, to provide device-independent approximations of flexibility with good accuracy, and much better scaling for long time horizons and many devices. An important aspect of the real-life implementation of energy flexibility is enabling flexible data exchange with many smart energy appliances and market systems, e.g., in smart buildings. For this, ontologies standardizing data formats are required. However, the current industry standard ontology for integrating smart devices for energy purposes, SAREF for Energy Flexibility (SAREF4ENER), only has limited support for flexibility and thus cannot support important use cases. In this paper, we propose an extension of SAREF4ENER that integrates full support for the complete FlexOffer model, including advanced use cases, while maintaining backward compatibility. This novel ontology module can accurately describe flexibility for advanced devices such as electric vehicles, batteries, and heat pumps. It can also capture the inherent uncertainty associated with many flexible load types.

Figures (5)

• Figure 1: A schematic description of the FOs life cycle (taken from DBLP:conf/eenergy/LilliuPSN23).
• Figure 2: Example SFO (a), TECFO (b), DFO (c) and UFO (d).
• Figure 3: dCO design overview.
• Figure 4: Overview of the flexibility module of dCO.
• Figure 5: UFO functions

Theorems & Definitions (1)

• Definition 1