By Jim Kohl
From the July/August 2014 issue of Today’s Facility Manager
Wireless devices are more common than ever before. In fact, there are more mobile connected devices than people on the planet today, according to Cisco’s 2013 Global Mobile Data Traffic Forecast. No wonder wireless communications technology has moved into the facility management world. Wireless networks enable the reliable performance of building automation system (BAS) technology and mission essential building systems, such as heating, ventilation, and air conditioning (HVAC).
Wireless solutions deliver a range of benefits for facilities of all kinds. But they offer distinct advantages in historic buildings and other older facilities. For example, wireless sensors can be installed almost anywhere and without penetrating the structure of a building. In addition, wireless solutions can be more reliable than conventional hard-wired solutions, particularly in buildings that may have been wired decades ago.
Many wireless systems use the building automation and control network (BACnet) protocol over the ZigBee Building Automation standards. BACnet allows the BAS to communicate directly with independent systems, including HVAC components that are equipped with direct digital control (DDC) technology. ZigBee Building Automation is the only BACnet approved wireless mesh network standard for commercial buildings.
Wireless BAS technologies follow Institute of Electrical and Electronics Engineers (IEEE) standards. These ensure that the building wireless network will coexist with other wireless systems used in the facility, including Bluetooth and Wi-Fi. Through the use of these industry-wide standards, the most capable BAS will enable secure and reliable wireless monitoring and control over current and future building systems.
Wiring in older buildings can fail permanently or intermittently when wires are cut, damaged, or disconnected. Redundant, self repairing mesh technology, which routes signals around obstructions, makes wireless communications links more reliable. And recent improvements include additional reductions in power consumption and longer life batteries for remote sensors. Meanwhile, high-performance routers can double the range of previous generation equipment, eliminating the need to install repeaters throughout a building.
There are three major advantages to implementing a wireless building automation solution in older facilities.
On time, on budget project completion. Wireless significantly simplifies control projects in existing buildings. There are fewer delays and labor costs are reduced because there are no wires to be pulled, tested, and repaired. Zone sensors, controllers, and other hardware can be installed quickly, without penetrating structures (often preferred in historic buildings). Hardware can be attached directly to a wall or ceiling, saving time and cleanup costs. Meanwhile, sensors can be easily moved to improve data collection and ensure occupant comfort. The cost of placing and relocating sensors is dramatically reduced. In general, it takes about 90 minutes per zone to relocate wired sensors, while it takes about 15 minutes for wireless sensors.
Easier problem solving. In a wireless environment there are no cut or compromised wires to cause the network to go down. Troubleshooting and repairing faulty wiring situated behind walls is eliminated, saving both time and cost.
It is also less labor-intensive to relocate sensors to improve comfort and energy efficiency. During the building design phase, it is nearly impossible to know exactly where sensors should be placed in a given room or office area because the designer does not always know where equipment will be placed. For example, the effectiveness of an HVAC sensor or thermostat may be compromised if positioned near a copy machine or other heat generating piece of equipment. This can cause the room to be overcooled. There may also be operational or aesthetic reasons why equipment cannot be moved.
Life cycle savings. Wireless solutions significantly reduce the cost of building control projects in existing structures. Major steps in the rewiring process can be eliminated altogether; for example, there is seldom a need to conduct a pre-installation site survey in most buildings.
Material and labor costs are reduced because establishing a BAS communications link is simplified. Designers are not “bound by the wire” when it comes to placing zone sensors and other system components. Sensors and user interface devices can be placed where they make the most sense from a systems efficiency perspective—on columns, cubicle walls, or wherever they can detect true conditions within the facility.