MetamEnTh: An Object-Oriented Metamodel for IoT Systems in Buildings

Abstract

Buildings consist of systems that have to interact and coordinate with various systems to function smoothly. It is essential to have models and representations of buildings in forms that are easy to read for effective simulation, control, and optimization of building systems. It is also necessary for integrating and creating novel applications and functions. A building energy management system (BEMS) is a common feature of most commercial buildings. It contains models of some aspects of the building and its systems. However, these models in the BEMSs do not entirely model all systems and subsystems and their relationships because their primary function is to control heating, ventilation, air-conditioning (HVAC), and lighting. Project Haystack and Brick have made significant progress in modeling buildings for operational purposes by adopting a metadata approach. They offer machine and human-readable representations of buildings, systems, and their relationships. However, tags and tagsets in the metadata approach have some limitations that stem from a weak structure in defining entities, their properties, and relationships. In this study, we identify seven problems with the metadata approach to modeling buildings and address these problems with an object-oriented metamodel: Metamodel for energy things (MetamEnTh). Using an object-oriented modeling technique to establish structure and constraints, MetamEnTh produces a model that portrays a building and its systems. MetamEnTh adheres to the same naming convention of entities as other projects, such as Project Haystack and Brick. We accomplish a UML representation of the core structure of MetamEnTh and validate the representation through three different case studies.