Web of Things Semantic Interoperability in Smart Buildings

Buildings are the largest energy consumers in Europe and are responsible for approximately 40% of EU energy consumption and 36% of the greenhouse gas emissions in Europe. Two-thirds of the building consumption is for residential buildings. To achieve energy efficiency, buildings are being integrated with IoT devices through the use of smart IoT services. For instance, a smart space heating service reduces energy consumption by dynamically heating apartments based on indoor and outdoor temperatures. The W3C recommends the use of the Web of Things (WoT) standard to enable IoT interoperability on the Web. However, in the context of a smart building, the ability to search and discover building metadata and IoT devices available in the WoT ecosystems remains a challenge due to the limitation of the current WoT Discovery, which only includes a directory containing only IoT devices metadata without including building metadata. Integrating the IoT device's metadata with building metadata in the same directory can provide better discovery capabilities to the IoT services providers. In this paper, we integrate building metadata into the W3C WoT Discovery through the construction of a Building Description JSON-LD file. This Building Description is integrated into the W3C WoT Discovery and based on the domOS Common Ontology (dCO) to achieve semantic interoperability in smart residential buildings for the WoT IoT ecosystem within the Horizon 2020 domOS project. This integration results in a Thing and Building Description Directory. dCO integrates the SAREF core ontology with the Thing Description ontology, devices, and building metadata. We have implemented and validated the WoT discovery on top of a WoT Thing and Building Description Directory. The WoT Discovery implementation is also made available for the WoT community.