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Wireless mesh technology, improved security, and reduced RF congestion are just some of the advances that have made wireless connectivity more attractive in BAS (Building Automation Systems).
We asked leading experts in the field to provide their clarifications on frequently asked questions and to comment on some interesting aspects of the new technology. The following took part in the conversation:
Tom Munson, Registered Communications Distribution Designer (RCDD), Director of TLC Engineering for Architecture (Orlando, Florida, USA);
Jay Hendrix – Manager, SBT Wireless (Buffalo Grove, IL, USA);
Terry Hoffman – Johnson Controls (Milwaukee, USA);
John Ruiz – Program Manager, Wireless BAS, Johnson Controls (Milwaukee, USA);
Jon Williamson – Marketing Manager, TAC North (Andover, MA, USA).
CSE: What are the key benefits of using wireless technology?
Munson: An important advantage of such technologies is the ability to install devices in difficult conditions, especially in existing buildings or in remote locations. In addition, the advantages include the mobility of such devices and the ability to install them quickly, as well as a reduction in overall costs due to the reduced need for wiring.
Hoffman:While one of the benefits is certainly the potential for cost savings by eliminating the need to run wires between sensors and controllers, I believe the main benefits of using wireless technologies are flexibility and ease of expansion of systems.
Companies need flexibility now more than ever. They (companies) as a whole must change in accordance with their changing needs. It is precisely this environment that encourages the use of wireless technologies, especially in the case of installing, for example, sensors in premises intended for rental. With wireless technologies, installing new sensors, both temporarily (to diagnose problems) and permanently (to expand an existing system), becomes much easier.
Hendrix:Using wireless technology also means that the layout of sensors can be optimized to ensure that they are located in the most relevant locations. In the past, sensor locations were typically determined by how easy it was to get the necessary wiring to them. This was often an issue in large shared office spaces divided into individual work cells, but now using wireless technology not only makes it easy to move sensors from one location to another, it also allows for more sensors to be used, increasing the data collection capabilities of the BAS.
Another benefit of using wireless technology is that it simplifies retrofitting. There is no longer a need to open up walls and ceilings to run cables and new wiring. This is especially true when using wireless devices that are powered by batteries or other existing power sources, as it eliminates the need to run new power cables.
CSE: How has the use of wireless technology affected the installation process?
Hendrix:I believe that the use of wireless devices facilitates coordination between different sectors during installation work. For example, a room sensor can be installed and put into operation at the very end of a project, and this operation does not need to be coordinated with other work providers at various stages of the implementation of the planned project. In addition, when using wireless technologies, the renovation is much less disruptive to the work of tenants in the buildings.
Using wireless technology also facilitates a gradual transition from old systems to new ones, allowing such work to be completed within budget and schedule. Often, the wiring used in older systems cannot be used in new systems.
Accordingly, it has to be relocated, and the system has to be upgraded in one step. This usually means that the old system has to be completely dismantled and the new system installed at the same time.
With wireless technology, the “transition” of devices to the new system can be done gradually, without affecting the operation of other devices connected to the old operating system.
CSE: What obstacles still remain in the way of using wireless technology?
Hendrix:One of the problems is the use of batteries for many wireless devices, such as sensors (batteries have to be replaced many times during the life of the devices). However, as the power consumption of these devices decreases, the technology used in the production of batteries improves, and alternative power sources such as solar panels and thermocouples are developed, the severity of this problem will gradually decrease.
Munson:Another obstacle is the lack of confidence in the reliability of protection of the systems being created from malicious external intrusion and from interference from other electrical devices. In essence, end users ask themselves: «Can I consider such a system reliable, and what should I do if this system really fails?»
Ruiz:These are the current user perceptions, and as technology advances, they are becoming outdated. In reality, properly designed wireless systems are as reliable and secure as wired systems, and as new technologies such as frequency hopping, mesh networks, and signal stretching are introduced into wireless networks, such systems are becoming even more reliable and secure.
Williamson:As with any new technology, adoption of wireless technology is expanding as it becomes more tried and tested in the field. Over the past three years, manufacturers have devoted significant R&D resources to improving the reliability and security of wireless solutions to meet user expectations. The technology has now reached a level of maturity where it can meet customer goals and requirements at an attractive price point for a wide range of applications.
Hendrix:However, it is still true that the cost of additional electronics required to create wireless networks still exceeds the cost of installation work eliminated by using wireless technologies, but this issue is constantly changing as more and more electronic devices begin to use single-chip circuits, the cost of which is rapidly falling each year.
In addition, the lack of technical compatibility between different wireless devices is still a problem.
Further standardization work is needed to address this issue.
CSE: There are arguments for using wireless devices in almost any building, but what types of buildings are best suited for wireless technology?
Hoffman:Generally speaking, wireless devices are naturally most suitable for buildings where wiring is impossible or difficult to install. The reasons for this may be purely cosmetic, or related to, for example, general safety or health concerns. In addition, wireless networks are economically justified in cases where conventional networks would require wiring through contaminated areas or through underground areas flooded by groundwater. Examples abound.
Williamson:When developing any project, it is necessary to use best practices for planning wireless networks, taking into account the impact of various physical obstacles and building materials on their future operation. There are four types of buildings in which the use of wireless solutions is especially attractive: urban buildings, clean workshops, historical buildings and buildings remote from immediate neighbors (including buildings to which and in which wiring is difficult).
For example, in cleanrooms, it is necessary to precisely maintain the specified pressure and microclimate, so any violation of the integrity of the boundaries of the production zone worsens the working conditions in it. In historic buildings, it is important to maintain the integrity of their structures: this means that wires cannot always be laid in a straight line. Thus, to install a network in the next room, it may be necessary to lay up to a thousand feet of cable, while the length of a wireless connection will be only 10 feet.
Additionally, digging a trench to run cable to a remote building and punching holes in brick, concrete or glass walls can be difficult and expensive.
Hendrix: Offices, schools and universities, as well as manufacturing and other industrial buildings, are a wide range of applications for wireless solutions.
Buildings with fairly open interior and exterior spaces may be ideal for wireless technology, as they create minimal obstructions to the propagation of radio frequency signals.
Munson: Additionally, buildings with a large number of individual workstations are ideal candidates for wireless solutions. In fact, monitoring the status of individual workstations should be the primary motivation for using wireless technology.
Feeling comfortable and in control of your personal space can increase a company's revenue by making its employees happy and satisfied.
CSE: So how should building infrastructure be designed in the future to facilitate the use of wireless technology?
Ruiz:It is advisable to consider the use of materials that are radio-transparent. Wireless systems generally work best in open environments where there is no interference or absorption of radio frequency signals. In such environments, these signals can travel up to 300 feet, making wireless technology ideal for connecting sensors to measure temperature and control humidity in rooms.
Controllers are typically located 30 to 60 feet away from the sensors, behind ceiling tiles.
Porous materials like particle board, ceiling tiles, and cement blocks have less of an effect on wireless signal propagation than metals and concrete, where signals travel less than 100 feet.
Surprisingly, metal ducts sometimes help wireless signals propagate because they act as wave guides, helping signals travel between controllers.
Williamson:One of the recently developed technologies, wireless mesh networking, has the advantage that it does not require any special infrastructure to create. It is based on the fact that each node contributes to the construction of a reliable wireless network.
Wireless mesh networks differ from wireless Ethernet networks, which are based on a hub-and-spoke, multipoint architecture that depends on the location of the access points. In wireless mesh networks, each node is connected to other network elements by multiple paths and is aware of all of its closest neighbors. If one node is disconnected from the network, or if the path it uses to transmit data is blocked, the network automatically rebuilds its structure by finding the next closest node to resume transmitting messages. Since no infrastructure is required to set up a wireless mesh network, it is easy to see how much cheaper this makes them to build compared to conventional networks. As a result, the daisy chain connection of network elements is becoming a thing of the past.
Hendrix:That's right, mesh networks use a lattice topology to create multiple redundant communication paths, with each node acting as a transmitter, receiver, and router at the same time. Mesh networks can route signals around obstacles, and each node only needs to be connected to two or three other nodes.
Williamson:In fact, the IEEE 802.15.4 standard for wireless mesh networks provides much better wireless solutions for command and control systems than the ”WiFi” or ”Bluetooth” standards. Wireless mesh networks are self-forming and do not require special infrastructure, access points or routers, although they may sometimes need to include repeaters.
CSE: What other advances have been made in wireless technology recently, other than wireless mesh networks?
Hendrix:The power consumed by wireless devices is increasingly reduced, allowing such devices to operate on batteries for very long periods of time.
Hoffman:One of the latest trends is the use of systems based on distributed antenna technology. Such systems ensure coverage of all wireless systems in a building, including mobile phones, wireless LANs, VoIP and BAS. They also help improve security, as antennas can be designed to facilitate the reception of signals inside the building and prevent them from spreading outside.
Wireless system designers are also beginning to incorporate military-grade technologies. For example, to reduce interference, wireless networks use frequency hopping technology to dynamically select the frequency bands they use. They also use spread spectrum signaling, which spreads the signal across the frequency band they use. Advanced encryption algorithms are also being built into radio equipment to help increase the security of wireless networks. These technologies have long been used in military radios, and now they are becoming cost-effective for wireless BAS.
CSE: How do you envision the future of wireless systems in 10 and 20 years?
Munson:I believe that all devices will support wireless IP addressing technology with a minimum channel width for data transmission of 1 Gigabaud.
Hendrix: I foresee that in the near future, wireless devices will become low-cost infrastructure elements.
Their power consumption will continue to decrease, and alternative energy sources or technologies for harvesting energy from the environment will be used to power them, allowing such devices to operate virtually forever without any maintenance. Radio-electronic components will be built into all devices.
Sensors and electronic devices will be even smaller than they are today and will be embedded in all devices that need to be monitored and controlled to ensure their timely maintenance, as well as to maintain comfort and security in general. BAS control devices will also use larger wireless infrastructures that will be established everywhere by then. Each building will contain its own repository of information that can be monitored and processed via the Internet or automatically to optimize management, improve energy efficiency and ensure the comfort of people in that building.
Ruiz: We expect the evolution of wireless BAS to repeat in terms of technology adoption that is happening in the mobile phone and WiFi market.
This will also allow for more distributed and less hierarchical control and management systems. Due to their high cost and low reliability, mobile phones occupied only a relatively small niche in the market until the mid-1990s. As technology advanced, their cost fell and reliability increased, and the number of mobile phone users began to grow. Today, there are more than 1.5 billion wireless users worldwide, and the WiFi industry is growing at an equally rapid pace.
In addition, another phenomenon is observed in the WiFi networking industry: wireless equipment installation does not necessarily have to be done by experts.
Technology has advanced to the point that wireless networking equipment can be installed by an ordinary user in just one day. The same can be expected in the case of BAS: in the next 10 years, wireless networks will become the most common way to create BAS in commercial buildings.
With the creation of wireless networks based on standards such as WiFi and ZigBee, the current hierarchical structure of BAS will change. End devices such as sensors and actuators will become smarter and require less control. They will be equipped with user interfaces and embedded systems for generating alerts, recording schedules and setting schedules.
Integration between different systems will also become more common.
For example, time clocks will be able to transmit information to lighting, heating, ventilation and air conditioning systems about the presence of people in the room and, accordingly, a signal to take action.
Williamson:Over time, the number of systems that combine wired and wireless technologies will increase. Just as offices use a combination of wireless connection points and fixed access points to connect to local Ethernet networks, buildings will continue to have some control systems based on wired technologies. Wireless devices will become more common and will include a variety of peripherals: intrusion alarm sensors, temperature sensors, door contacts, and more.
Open protocols such as the ASHRAE «BACnet» protocol being developed will include wireless standards as an optional method of data transmission. By standardizing wireless communication technologies for use in control and management, it will be possible to integrate products from different manufacturers into a single mesh network based on their technical compatibility.
With the choice between the reduced installation costs of wireless mesh networks and the freedom of choice offered by open protocols, building owners are looking for a future in which they can provide safe and comfortable building conditions in ways that are cost-effective, efficient, and effortless.
In conclusion: the evolution of wireless standards
Any new technology poses the problem of incorporation into existing regulations and standards. This task usually falls on the shoulders of standard-setters and industry alliances, who are forced to work as hard as they can, putting aside personal preferences and corporate interests for the common good of the people who work and live in buildings.
«Unfortunately, petty squabbles and market positioning often get in the way of getting the right products to market in a timely manner. Standards committees continue to fight internally over when to stop fine-tuning and ratify the standards they create,» says Tom Munson. «In the wireless world, it appears that the Institute of Electrical and Electronics Engineers (IEEE) and the ZigBee Alliance, a group of control equipment manufacturers working to promote wireless networking through a global open standard, are leading the way.»
As John Ruiz of Johnson Controls puts it, «IEEE's efforts to create an open standard for low-power, moderate-bandwidth radios have resulted in the IEEE 802.15.4 standard. This standard has also been adopted by the ZigBee Alliance as part of the ZigBee standard version 1.0.
Version 1.1 of the ZigBee standard introduces additions aimed at improving the reliability and security of radio networks by adding the use of mesh network architecture and advanced encryption algorithms. In addition, at the ASHRAE meeting held in January 2006, a working group was formed to determine how to include ZigBee support in the BACnet communications standard.”
This article is based on materials from the journal Consulting Specifying Engineer
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