If you were to look at a building automation system 20 years ago, chances are good that it was based predominantly - if not entirely on a single manufacturer. Proprietary systems would provide a unified tool set and device interoperability, but only within the confines of a particular brand (Honeywell, Johnson, Siemens, etc.). This proved to be limiting in both keeping up with current technology and providing competitive options for purchasing and service.
Additionally, these proprietary systems are siloed within their own subsystems, such as HVAC, energy, lighting, and security. In order to achieve an integrated and cost effective smart building, open standards emerged, offering new options to solve the proprietary challenges. Here's a primer on both open device standards and open data standards in the smart building industry.
Early on, there were multiple protocols often competing for the emerging open standard space in HVAC. They were BACnet and Lonworks. The BACnet standard was born out of necessity and has its roots in the need for both Cornell University to unify its campus and also a standards body within the ASHRAE organization. The BACnet standard evolved as a definition of how devices would talk to each other. Initially as a low-level protocol on RS485 (BACNET MSTP) physical layer and eventually to also communicate across ethernet (commonly known today as a local network or LAN).
In order to encourage interoperability and test protocol compliance, the BACnet testing labs (BTL) was formed. This independent testing lab is used by device manufacturers to certify their hardware and software to be BACnet compliant and hence display the BTL logo.
Around the same time, a chip manufacturer, Echelon, developed their own protocol and embedded it on a communications chip. Their approach to solving open protocol was to standardize the physical layer to a new FTT-10 physical layer by having manufacturers implement their communication chip into their devices. The novel approach of implementing the open protocol via a chip proved to be challenging as manufacturers of devices are typically cost sensitive and this proved to be a barrier to entry. Additionally, the protocol was designed to be comprehensive and crossed multiple silos in an intelligent building to include HVAC, lighting, energy, and security. Unfortunately, the complexity of describing points across a wide spectrum of input and output types proved to be difficult to implement. The Lonworks protocol also had a testing body to verify interoperability and if manufacturers' devices passed this test they would be Lonworks certified.
Meanwhile, in the lighting industry, an open protocol born in Europe by the KNX organization developed its protocol for communicating devices. This protocol also communicated on the serial physical layer and has also evolved to communicate on a LAN via gateway. The KNX network protocol is flexible in that it is used for HVAC and lighting systems. The popularity of the protocol in Europe also crossed over from commercial to residential markets. Similar to other open protocols, KNX devices can also be certified through the KNX certification.
Another standard protocol is Digital Addressable Lighting Interface (DALI). DALI was originally developed to control fluorescent ballasts, and has replaced that simple one-way control with more sophisticated two-way communication between individual devices. With the addition of digital control, DALI devices can operate in groups, enabling easy reconfiguration in software, eliminating the need to change physical wiring. The physical layer for DALI is a combined power and data carried by the same pair of wires that is polarity insensitive. The certification program, called DALI-2, is based on the latest version of the DALI protocol, and is developed and maintained by the DALI Alliance.
In the electrical monitoring and control of a building, the need for open protocols also developed a standard called Modbus. Electrical devices such as power meters, switchgear, and power monitoring devices communicated using the MODBUS protocol. It is also now a popular protocol in industrial markets, as well as with HVAC equipment manufacturers' controllers. This protocol initially started out with RS485 physical layer and was called Modbus RTU. In later years the protocol evolved to be Ethernet compatible with the update as Modbus TCP/IP. The Modbus Conformance Testing Program provides independent verification that qualifications have been met in compliance with Modbus specifications.
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Fast forward to modern day. Thanks to open protocols and testing labs, system integrators and building owners can now enjoy using the best of breed products for their intelligent buildings. With all these connected devices, a new problem (opportunity) has emerged, as lots of data is now available from our connected world. The challenge is how to leverage this data to derive value, which inevitably begins the discussion about open data standards.
Smart buildings have numerous devices, equipment, and systems all working to collect operational and energy performance data. The challenge is making sense of this data. Due to the poor semantic modeling (no standard naming), it requires labor intensive processes to “map” the data before value creation can begin. The Haystack Standard is an open source initiative that provides a new ontology and taxonomy to make data self-describing. This allows applications to programmatically connect to the data for analysis, visualization, control, and better management.
The metadata standard is a practical implementation for automated buildings and is utilized and sponsored by many leading building automation and application companies (including J2’s FIN Framework).
Another approach for holistically dealing with the increasing amount of building and asset data is Brick Schema. Brick is an open-source effort to standardize semantic descriptions of the physical, logical, and virtual assets in buildings and the relationships between them. Brick consists of an extensible dictionary of terms and concepts in and around buildings, a set of relationships for linking and composing concepts together, and a flexible data model.
The schema is rooted in the academic community and is gaining increasing support by some building automation companies. There have been recent conversations around bringing the two open standards (Haystack and Brick) in better alignment. Check out this 2022 Haystack Connect presentation to learn more.
As they say, a rising tide lifts all boats. Don’t wait and watch to see which standard wins, jump in and learn more about the benefits of adopting open standards. Our history has shown that it’s more about evolving towards a common goal and committing sooner than later and letting the industry grow together.
Topics from this blog: Project Haystack BACnet KNX Smart Buildings Technology
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