“The effective harmonization of building data from different systems has long posed a challenge. Recently there has been a big push in the smart buildings market to develop improved frameworks, models and ontologies for smart building data management,” reads our latest research study on the IoT in buildings. “New semantic data models that provide a common means of structuring and tagging data to represent it in a specific logical way across systems are being developed to support data governance, regulatory compliance, and data management demands in building data environments.”

Project Haystack is an open-source initiative to streamline working with data from the Internet of Things. Established in 2011 by Intel, Legrand, Lynxspring, Siemens, CABA, and others, the open-source initiative provides a standardized and contextually-rich approach to representing and using metadata across a wide range of applications. Haystack is already in widespread use, and as of April 2021, the organization estimates that the standard is active in over 40,000 sites worldwide.

Brick Schema uniform schema defines a concrete ontology for sensors, subsystems, and the relationships among them using technologies developed for the semantic web. It was launched in 2016 as a collaboration between  IBM Research, Carnegie Mellon University, UC Berkeley, the University of Southern Denmark, and others. 

“Brick excels in defining classes and relationships for HVAC and electrical systems and is expanding to incorporate domains such as security and access control, fire protection, location tracking, and AV equipment,” explains our in-depth report. “Brick is being used by building systems manufacturers to create easier data harnessing and interoperability with other building systems. Some end-users and building operators are now demanding that their building systems providers comply with the Brick schema.”

This blog post written by Erik Paulson in 2021, is a great comparison of the Brick Schema and Project Haystack. As noted in the blog, "Haystack version 4 is moving towards embracing a formal taxonomy and ontology and incorporating it into the next version of the Haystack standard".

RealEstateCore is another rising open-source ontology, developed by a Swedish consortium of real estate owners, software houses, and research institutions. Developed from the property owner's perspective, RealEstateCore is a modular ontology, that is, a collection of data schemas which describe concepts and relations that can occur in data that is generated to model buildings and building systems, or that is sourced from such systems. In order to accelerate adoption, the consortium has partnered with Microsoft to make RealEstateCore the key ontology for the popular Azure Digital Twins.

The RealEstateCore website includes a table (see below) which gives an indication of how some major standards for buildings cover the property owner’s perspective.

The Digital Buildings project by Google is an open-source, Apache-licensed initiative that aims to manage very large, heterogeneous building portfolios in a scalable way by enabling the management of applications and analyzes that are “trivially portable between buildings”. The Digital Buildings ontology and toolset are already being used to manage Google’s own buildings around the world, including their 88 acre Googleplex campus in Mountain View, California. Google has been clear that Haystack & Brick have “inspired” their project and maintaining “cross-compatibility and/or convergence with both is a long-term objective”.

Another ontology is Quantum, a partnership between building automation platform provider PassiveLogic and the US DoE that offers “a fully descriptive language for systems, buildings, and the interconnections between them”. The IoT Access Protocol (IAP), meanwhile, offers a platform-agnostic open data and services access protocol standard that aims to develop a “data and services fabric” that connects all elements of a smart building infrastructure. And, other initiatives, like the Ontology Alignment Project (OAP), seek to bridge the gap between naming and tagging standards in the building automation industry.  

“There are several schemas and ontologies used in the industry today, with no true consensus or front runner, it feels too often that this decision–what ontology to use– must be made before everything else,” a Buildings IOT official told Fierce Electronics. “This slows down the process of creating smart buildings as time and effort is spent on picking the data model to apply. Often owners can become paralyzed by these decisions, which prevents them from moving forward at all.”

Change is coming. Project Haystack, Brick Schema, and Digital Buildings announced a liaison agreement with The Digital Twin Consortium in February of 2022, marking their intention to collaborate on standardization and interoperability requirements. ASHRAE Standard 223P, which we wrote about in 2018, is still under development by a working group of the BACnet committee. RealEstateCore, meanwhile, has presented “common ground” for modelling smart buildings while leveraging other industry standards to prevent reinvention, offering various degrees of alignment with ontologies and other initiatives. Memoori believes there will be further convergence/standardization between leading standards.

“Each ontology is seeking to increase community engagement to address the needs of a broader range of system types and functions, and each has its benefits which have already driven adoption to varying degrees. However, without a degree of convergence between these different initiatives, the field of building data management risks becoming as fragmented as that seen for communications standards and smart building protocols,” our new report explains. “Moving forward, cross compatibility and/or convergence between key ontologies such as Brick, Haystack and RealEstateCore could prove to be a real game-changer for the standardization of smart building systems.”