RealEstateCore, a smart building ontology for digital twins, is now available

Published Feb 16 2021 10:59 AM 21.3K Views

The open-source Smart Building RealEstateCore ontology for Azure Digital Twins is now available for you to accelerate time to market, enhance interoperability and extensibility of your smart building solutions and the reusability of your code. Here are the details of why, what, and how, along with pointers for you to get started and begin using the ontology in your solution today.

What is an ontology and why is this needed?

An ontology, leaving aside complicated academic jargon, is essentially a shared data model for a given domain, like a building structure, IoT systems, a smart city, the energy grid, web content, etc. Ontologies are often used as schemas for knowledge graphs, as they can enable:

  • Harmonization of software components, documentation, query libraries, etc.
  • Reduced investment in conceptual modelling and system development.
  • Easier data interoperability on a semantic level.
  • Best practice reuse, no need to make the same mistakes others have already done and learned from.

Azure Digital Twins and its underlying Digital Twins Definition Language (DTDL) are at the heart of Smart Building solutions built on Azure. DTDL is an open modeling language based on JSON-LD and RDF, by which developers can define the schema of the entities they expect to use in their graphs or topologies. Since DTDL is a blank canvas which can model any entity, it is important to reduce developers' time to results by providing a common domain-specific ontology to bootstrap solution development, as well as seamless integration between DTDL-based solutions from disparate vendors. Property owners and smart building solution providers alike have been asking for smart buildings' ontology, and we are proud to see the accelerated success they have begun to achieve with this new release.

How have we implemented?

Our partnership with the RealEstateCore (a Swedish consortium of real estate owners, software houses, and research institutions) has delivered an open-source DTDL-based ontology (or set of models) for the real estate industry, which provides common ground for modeling smart buildings while leveraging industry standards (like BRICK Schema, W3C Building Topology Ontology) to prevent reinvention. As part of the delivery, we also provide best practices for how to consume and properly extend the ontology. We hope it will be widely adopted and/or extended by developers, and strongly encourage active participation and contribution.




We (Microsoft, RealEstateCore and Willow) partnered over many iterations to bring the best models to represent majority of customers’ use cases and requirements. We have applied these Ontology Design Principles and we aimed to keep the models simple, flexible, yet balanced in this ontology. We kept compatibility with many standards to avoid confusion and reinvention. We optimized the models for query performance and defined flexible relationships while establishing model inheritance, semantic units, and reusable components. By using inheritance, and specifically multi-model inheritance, we are aiming this ontology to be industry-first. Similarly, by defining the properties and relationships, it provides the industry a much richer common data schema that can be adopted for interoperability. This ontology covers multiple areas: real estate, building structures, equipment (HVAC, plumbing, electrical, IT, etc.), agents (person, organization), sensors and actuators, and many more.


Watch this IoT Show episode to learn how we define real estate types and relations, how these models can be uploaded and used in Azure Digital Twins and exemplify how queries built against these models can be reused across multiple deployments to prove the benefits of model standardization and data interoperability.



Partners adoption

A key principle driving our ontology work is to ensure that any models we develop can be easily deployed by industry partners in real world projects. These efforts help take ontology discussions out of theory and into applied practice, validating that not only does the RealEstateCore ontology save developers time, but it also provides lasting value to property owners managing many disparate solutions as well.


Idun deploys the RealEstateCore ontology in its ProptechOS solution to their biggest customers, Vasakronan, Sweden’s largest property company and YIT the largest Finnish and a significant North European construction company and urban developer. ProptechOS has a large install base in Europe that will be upgraded to the new solution and further rollout are planned in CY2021.


Willow has integrated the RealEstateCore models into its WillowTwin solution, deploying it to Brookfield Properties iconic high-rise building One Manhattan West and other major commercial assets. The RealEstateCore ontology has completely transformed Willow’s software development process and saved them 200+development hours in the span of just one month.


Read more about these customer stories and how Microsoft is unlocking the potential of the smart buildings ecosystem here.

Calls to action

We invite you to explore our repository to find out how we have implemented it, how to upload it to Azure Digital Twins using Model Uploader, how to visualize it using Azure Digital Twins Explorer and how to extend it and contribute.


We strongly recommend developers to use it in their solution today, to actively participate and contribute by filling issues and sending pull requests. For property managers and customers, start applying it to the solutions that are onboarded into your properties.

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‎Jun 21 2021 07:36 PM
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