New processing prowess finding its way into building automation systems

  • May 29, 2014
  • Feature

By Punya Prakash, Texas Instruments

The amount of electronic intelligence around us is growing by leaps and bounds, from those amazing smartphones to new wearable computer devices, as well as a myriad of embedded industrial systems that we take for granted every day. Building automation systems are striving to keep up with this renaissance in processing prowess by incorporating hierarchical and distributed architectures, low-power processing and control capabilities, advanced sensors and many other exciting new technologies. In fact, sometimes the most pressing challenge is how to make sense of it all. Why innovate? Owners and operators of commercial buildings, and even residential homeowners, are keenly aware of the cost of energy and the amount of electricity consumed by a building. Reducing a building’s energy consumption is essential to remaining competitive in the commercial real estate market. In the US today, commercial buildings account for roughly 40 percent of the country’s energy consumption. In addition, the increasing demand for electricity has driven energy generation in recent years. Between 1985 and 2006 the generation of electricity expanded by 58 percent. As demand increases, so do costs. By incorporating the latest advancements in electronic technology, a building automation system (BAS) is better equipped to effectively control costs on two fronts. First, a building’s demand-based services like heating, ventilation and air conditioning (HVAC), lighting, water and others and secondly, by efficiently managing the ancillary operational services like elevators, security systems, fire detection and others.

In addition to controlling costs, advanced BASs play a critical role by ensuring the building is operational. Many owners and operators have realized that buildings now require a greater degree of energy self-sufficiency to counteract the increasing incidence of rolling brownouts, blackouts and the vulnerabilities inherent in the electrical grid. The building must be able to compensate for any inadequacy of failure in the electrical distribution network. Moreover, an innovative BAS should be able to detect, diagnose and, in some cases, self-heal failures and faults in the building’s operational systems as well as the BAS itself. Automatic adaptive failure recovery initiated by the BAS enhances the reliability of building systems and limits any downtime. Architectural issues Many of the more sophisticated BAS networks in development today have adopted a hierarchical topology (Figure 1) since this structure is well suited to distribute intelligence throughout the building where it is needed, while at the same time, maintain a cohesive centralized control capability. Such a BAS is usually composed of a primary bus or communications channel, as well as secondary buses.  

The primary bus interconnects all of the centralized subsystems and applications that make up the building management service (BMS) system, such as the building’s central computer(s), monitoring unit, energy management unit, and security and fire detection systems. In addition to linking the BAS’ top-level management systems, multiple gateway devices or controllers usually communicate over the primary bus as well. These devices aggregate and concentrate the data from the various building control systems (BCS) located throughout the facility. The BCSs are typically fed information from zone controllers and end node devices, like sensors, intelligent thermostats, lighting systems and others. Net effects In addition to their hierarchical topologies, BAS are quite heterogeneous in terms of the technologies, communications protocols and types of devices that comprise them. Due to this diversity, it is important that powerful processing capabilities are embedded throughout a particular BAS deployment to facilitate cohesive interaction among the underlying technologies and devices. Not long ago the backbone networking technologies that made up most BAS were wired technologies such as RS-485, Ethernet, CAN or others. These technologies still form the basis for most BAS implementations, but wireless networking technologies such as WiFi, Bluetooth and ZigBee can be cost-effectively deployed in building automation networks to supplement the wired backbone communications. Wireless communication is often found at the top and bottom of the BAS topology, where it plays a role as a connectivity technology for both users of end node devices like thermostats and at the top of the hierarchy where operators might interact wirelessly with the systems in the BAS’ control center. A BAS network rarely relies on just one communications protocol. Unlike legacy automation equipment that typically only supported one protocol -- the proprietary protocol provided by the equipment’s manufacturer -- much of today’s equipment can support a range of communications protocols. Now, several protocols that had previously been proprietary, including BACnet and LonMark, have transitioned into industry standards. In contrast to these, several other protocols, such as Modbus, were developed from scratch as open standards for building automation. However, the critical point to note is that many of today’s BASs will run a multiplicity of communications protocols concurrently. Here again, powerful processing embedded in a particular BAS is needed to perform the seamless and instantaneous cross-protocol conversions that will be required for the pieces of the BAS to communicate with each other. One more fly in the building automation ointment is intra-building communications. Previously, most BASs were self-contained in one building. A BAS was limited to the automation devices and control nodes in the building being automated. Now that access to the Internet is ubiquitous and the Internet-of-Things is becoming a reality, building owners and operators are finding greater economies of scale in building automation by widening the traditional scope of a BAS to include multiple buildings. It is more cost effective to control and automate multiple buildings than it is to control just one. This intra-building networking often introduces additional protocol processing and another layer of complexity into a BAS. Moving Forward If the immediate past is a prelude to the future, it’s safe to say that building automation will continue to evolve as it incorporates new technologies and innovative techniques when appropriate. For example, in the area of the user/operator experience, there’s been a great influx of creative solutions in recent years, such as touch displays for control panels, wireless connectivity and engaging easy-to-understand graphics. Certainly this trend will continue, but this raises the issue of how to future-proof a BAS that’s being installed today. In this regard, the adaptability and agility of the base technologies that compose a BAS will be crucial moving forward. Most BASs are designed to scale as the network grows with additional controllers and end nodes or as the building is expanded with more space or new tenants. But beyond these expected changes, the integration of new technological advancements into a BAS will require a certain degree of flexibility in the already installed technologies. Powerful programming tools and graphical application programming interfaces (API) will be an essential part of the toolkit for users and BAS equipment manufacturers moving forward.

About the Author:

Punya Prakash leads the Energy Automation business for the Sitara™ processors product line at TI. She is responsible for support and growth of business opportunities for embedded processors with a key focus on solutions for connected home and building automation. 

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