In the 1950s the first centralized building control centres were developed. These were free-standing, hardwired and pneumatically-piped panels, with switches, controls and pilotlights to control and monitor the equipment in many mechanical rooms (Fig.1). A typical control centre had graphics and schematics mounted to the face. Although these systems had definite benefits, the cost was high and expansion capabilities were limited.

In the 1960s, multiplexing was introduced to the Building Automation System. Multiplexing was a switching technology, similar to that used by the telephone companies. Remote switching panels, which served as junction panels for temperature sensors, control set point adjustment etc. were strategically placed throughout the building and connected to a central console. Central consoles had a built-in slide projector that could display building schematics and HVAC system layouts on a display screen (Fig.2).

In the early 1970s, solid-state logic technology replaced noisy electromechanical relays, while digital type sensors were employed for temperature sensing. Data could be transmitted over transmission loop wiring at speeds up to 50 kilobits per second (that's comparable to the transmission speeds of 56K faxmodems used on PCs today). The central processing unit had enough memory storage for alarm limits, time based programming and equipment status alarms. Printers provided hardcopy readouts and operator's terminals had colour CRT displays. During this period, customized software was also developed, making these systems the first "intelligent" software-driven BASs, and the first step toward the integrated building.

The application of minicomputers to the BAS was a major development. These computers had the ability to fulfill all building automation requirements and generate management reports (Fig.3). However, these systems were extremely expensive and required specially-trained, highly skilled personnel to operate them. Consequently they were, for the most part, used only in large building complexes where high paybacks on energy and manpower savings could be achieved.

In the early '80s, microprocessor-based technology gave birth to two major inventions that have come to define the modern BAS: PCs and Direct Digital Control (DDC) controllers. DDCs are software-driven controllers containing HVAC control strategies and functions formerly performed by pneumatic or electrical controllers. The DDC controllers communicate with one another and with a host PC over a communications bus (Fig. 4). Powerful BAS software, with sophisticated graphical interfaces allow users to control and monitor building functions with point and click simplicity.

 

Sorry, I don't speak 1110010011001
Despite the development of digital technology in the '80s, integrating building systems and subsystems was difficult and costly, mainly because equipment from the various manufacturers spoke different "languages". To make the systems compatible, manufacturers have used gateways, devices that translate the code used by the equipment of one manufacturer so that another manufacturer's equipment could communicate with it. While gateways allow a certain level of integration, they can be expensive and require frequent upgrades.

 

Establishing protocol
Over the past several years, open data communication protocols have been developed to facilitate systems integration. An open data communications protocol defines a set of rules that allow different devices in a computer network to communicate with each other regardless of who manufactured them. With the use of open communications protocols, buyers are able to integrate equipment from different vendors into their BASs much more easily than before. Installation costs are reduced and system upgrades are more cost-effective. While many data protocols have been developed, the two most prominent are BACnet™ and LonWorks.

 

BACnet™ (Building Automation and Control network) is a non-proprietary data communication protocol introduced in 1995 by the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE). To prove their equipment is BACnet™ compliant, manufacturers provide a Protocol Implementation Conformance Statement which describes their product's BACnet™ capabilities. Thousands of BACnet™ systems have been installed around the world. This past winter ASHRAE approved an addendum to BACnet™ called BACnet/IP which allows manufacturers to build internet capabilities directly into their BACnet™ compliant devices. This will make it much easier for users to monitor and control building functions over the internet. Further, planned improvements to BACnet™ will make it easier to integrate fire safety and other life safety systems.

 

LonWorks is a proprietary data communications protocol which was developed by the LonMark Interoperability Association, a group of 36 companies from different industries with interests in systems integration. In order for their devices to be LonWorks compliant, manufacturers must install the LonWorks Neuron chip. Despite the need for proprietary technology, LonWorks is gaining wide acceptance in the HVAC industry. Today, more than 3500 companies are designing products using LonWorks technology. The LonMark Association is also working on protocols for greater control of LonWorks compliant systems over the internet.

 

The future is bright and less expensive
With reductions in both complexity and cost due to better and cheaper digital technology, open data communications protocols, and the internet, more and more building owners and operators are now able to benefit from the control, flexibility, ease of operation, and energy efficiency made possible by today's Building Automation Systems.

 

Will all buildings - industrial, commercial, residential - one day, be "smart" buildings with fully-integrated systems that provide the right function at the right time and use just the amount of energy needed? While pondering the possibility, I'm reminded of the opening sequence of a certain 1970s television show, in which the people faced with the challenge of creating a bionic man proudly declare: "We have the technology"

 

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