Committee drafts standard to guide future installation.
The maturation of communications technologies and the expansion of industry standards relating to cabling systems and protocols have made facilities and IT managers hungry for a single cabling system that serves an entire building. The resulting demand is directly responsible for the development of a new standard from the same group that brought you TIA/EIA-568 A. Three years after it began work on a specification for building automation systems (BAS), standards-making committee TIA TR 41.8 has drafted ANSI/TIA/EIA-862, “Building Automation Cabling Standard for Commercial Buildings.” The committee has now done for building automation systems what it did for building telecommunications cabling.
Originally called SP-3-4655-B, the standard enables the planning and installation of a structured system for BAS applications used in new or renovated construction of commercial buildings and campuses. The document establishes performance, topology, and technical criteria on various cabling system configurations for accessing and connecting BAS equipment.
The functions supported by building automation cabling include environmental management (HVAC), lighting/power control, security and access control, and fire and life safety. In some cases, audio/video paging and service/equipment alarms are also included.
Need for integration.
The concept of an intelligent building first emerged in the '80s when building control system manufacturers developed their own proprietary control/communications system for services like HVAC, lighting, and security. The control systems used different cable constructions and had difficulty communicating with one another. And until recently, these control systems used complex, proprietary, hierarchical architectures, making it difficult to link together systems from different manufacturers. Connecting these disparate control systems required expensive controllers, costly gateways, and complex software. As a result, many system vendors are shifting away from proprietary protocols and turning toward standards-based, or open, protocols.
Open system integration has a number of benefits, one of which is its ability to share information among disparate systems, which can reduce the total number of devices and reduce costs. For example, a single room occupancy sensor can notify the lighting control, HVAC, and security systems to the presence of occupants, allowing them to take appropriate action: lighting goes on or off, the HVAC adjusts temperature, and the security system provides alarm annunciation if an intruder is detected during an unoccupied period.
End-users' need for open, interoperable products led to the emergence of open protocols that have allowed products from a number of manufacturers to speak a common language. One such solution, the Building Automation and Control Network (BACnet), is an ASHRAE standard for computers used in building automation and control systems. Almost every major vendor of building automation and control systems in North America offers new products that support BACnet.
Consider also that the Ethernet protocol, which is becoming a sort of de facto communications standard, is being studied by a number of standards-making groups. For example, IEEE Standard 802.3af, “Power Over Ethernet,” which is currently in development, will address the concept of delivering 48VDC power to equipment on a network's UTP (unshielded twisted-pair) copper cabling. Such a power delivery system could apply to voice over IP, wireless access points, building automation system sensors, security access gear, and lighting control.
Two groups, the Open DeviceNet Vendor Association (ODVA) and the ControlNet joint special interest group (JSIG) are developing standards for an Ethernet industrial protocol (EtherNet/IP). The latter has selected an RJ-45 plug and outlet design with a protective bayonet style outer housing for use in harsh industrial environments. In addition, the TIA's TR-42.9 Industrial Telecommunications Infrastructure Group is working on the environmental requirements for this type of hardware. A suitable cable will also be part of the new industrial Ethernet standard.
Although BACnet, LonWorks, and proprietary protocols still dominate the core infrastructure of BAS networks, Internet protocol (IP) is still prevalent in several parts of building automation systems. A number of companies manufacture devices that access the control network using IP. By integrating control networks with IP-based data networks, a company can leverage an installed data network to distribute its environmental and control data. Control data is accessible through PCs connected directly to the network. The data, which is used for diagnostics, troubleshooting, and trending, can be used locally on the control network.
Now a facilities manager who previously never had access to basic environmental data can monitor a building's lighting usage. For instance, power consumption can be tracked by zone or time of day. The manager can monitor and plan the optimal use of power, air conditioning, or heating, based on established patterns, and a building owner doesn't have to pay for multiple networks. If a small cell of controls exists on the other side of the building, an existing IP network can be used to make the connection, rather than installing another local area network.
Several factors are at work to put all, or nearly all, of a building's services on a single network. And if the development of standards and communications protocols doesn't encourage the further implementation of building automation systems, it could provide the following benefits:
The use of one set of pathways and communications spaces, such as closets and equipment rooms, increases the square footage available for rental income. Even more economic benefits are possible when you reduce the number of contractors installing and commissioning the systems.
According to a recent survey, it's possible to save as much as 30% of the initial cabling costs on a building project. At the same time, the cost of ongoing system maintenance can be reduced by 60%.
By properly identifying system elements and maintaining accurate records on all moves, adds, and changes, troubleshooting and repairs can be handled faster and more efficiently. This also makes it easier to comply with the labeling and record keeping procedures required by the TIA/EIA 606-A standard.
Think primarily of a BAS as a diagnostic tool. The information logged and made available for analysis can accelerate the troubleshooting of mechanical problems and equipment failures.
A BAS that monitors and controls the electric power system can issue load shed commands and monitor power status from a central workstation. It's also easier to maintain a log of shed/restore commands and metering data. Additionally, full integration of this particular function with a lighting control and monitoring scheme can reduce power without making it obvious to tenants.
Constructing a solid foundation.
If a number of functions are going to be placed on a single network, a lot of attention should be given to specifying the cabling plant. The best approach may be to plan a cabling infrastructure around the cable types specified in the ANSI/TIA/EIA-862 standard. However, this lineup of cable types could be expanded or upgraded to include the following:
- High-pair count Cat. 3 cable
This cable selection presents an affordable way to use various telephone services like conventional analog/digital PBX and high-speed Internet connections like T1, ISDN, and DSL.
- Upgrade from Cat. 5e to Cat. 6 cable
This option can support Ethernet (10 Mbps), Fast Ethernet (100 Mbps), and Gigabit Ethernet (1,000 Mbps) as well as future technologies. The newer designs of copper-based structured cabling offer vastly improved transmission performance in terms of return loss, equal level far-end crosstalk (ELFLEX), and delay skew.
- Single- and multi-mode optical fiber
Selecting this medium for backbone cabling eliminates any concerns regarding the length and bandwidth limitations of copper media at a facility.
Within the horizontal cabling run, the ANSI/TIA/EIA-862 standard introduces two terms not found in TIA/EIA-568: horizontal connection point (HCP) and coverage area cable. The HCP is similar to the consolidation point (CP) used in open office (zone) cabling in TIA/EIA-568-B.1, since both are located somewhere in the horizontal cabling run between the telecommunications room and the user/device. Coverage area cable is the portion of the horizontal cabling that connects either the BAS outlet or the HCP to the BAS device.
With a telecom system in the 568 standard, a CP can be used to provide a cross-connection function between the telecommunications room and a telecom outlet. With a BAS system in the 862 standard, an HCP can be placed between the horizontal cross-connect in the telecom closet and a BAS device. The horizontal cabling from the HPC can also go to a BAS outlet and then to a BAS device. Of course, the cabling can also run directly from the horizontal cross-connect to a BAS outlet and then to a BAS device. Fig. 1 on page 41 shows the three BAS horizontal cabling options. In all cases, the distance limitation is 90 m.
As with the TIA/EIA-568-B standard, ANSI/TIA/EIA-862 calls for the HCP or BAS outlets to be wired in a star topology from the telecommunications room, although bus or ring layouts are also possible, using multi-point connections.
Unlike home automation, which was surpassed in popularity by home networking, building automation is making the dream of integrating a building's control systems a reality. And thanks to the passage of ANSI/TIA/EIA-862, systems integrators and cabling installers have a definitive blueprint upon which to base their system designs.