The evolution of connectivity for building automation
Buildings are evolving rapidly as developers try to maximise their returns, users’ expectations change, and climate-change mitigation becomes urgent. Building automation systems are being updated to address these concerns.
Changing expectations of buildings
Why the shift to intelligent buildings? The large capital investments involved in a new-build project mean that the resultant space must work as hard as possible during its operating lifetime to maximise profitability. With the rapidly changing nature of work, leisure, manufacturing, logistics, retail and care, buildings must be able to adapt to new circumstances. Coworking company WeWork demonstrated the principle by adapting legacy city-centre buildings into flexible office space. Now the pandemic has taught us that, in extremis, exhibition complexes can become hospitals, gyms can become vaccination centres, and our homes can become our workplaces.
New buildings must be designed to ensure that their physical space can be easily and cost-effectively adapted. They must also have a flexible smart building infrastructure that can be quickly reconfigured to deliver the necessary power, lighting, HVAC, IT, and data networks to wherever they are needed, however the building is configured.
Buildings also need to be rethought to minimise their climate footprints. Some of this can be achieved through stricter building codes, innovative materials, and new approaches: for example, employing wireless connectivity instead of structured cabling, to save raw materials such as copper. Intelligent building strategies can also mitigate one of the largest climate impacts of buildings: the way they are used. For example, combining presence detection with room-by-room HVAC and lighting control can stop office space being heated, cooled, or lit when it is unoccupied.
Smart buildings are also being equipped with comprehensive surveillance and security measures, to protect them against a variety of threats. These measures can include IP-based security cameras, presence detectors and, since the pandemic, thermal imaging at building entries to recognise people with elevated temperatures. Footfall-counting systems, enabled by infrared sensors, are also being introduced to track how many people are in a room at once.
These advances in technical infrastructure can help smart building-management systems adjust HVAC settings to match occupancy levels. They can also provide the raw data needed to understand the dynamics of a building’s occupancy – useful, for example, for tracking consumer trends in retail spaces or optimising the deployment of staff in many other contexts.
The pandemic has also taught us that buildings can have an important impact on our health. HVAC systems are being uprated so that they can monitor and improve air quality, using sensors to detect heat and humidity, as well as the concentration of key gases such as oxygen, nitrogen, and carbon dioxide.
Lighting is another critical aspect of intelligent building strategies. Properly designed lighting can encourage consumers to buy more in shops, enable office workers to concentrate for longer at their desks, and help people enjoy their time in social spaces. One way to deliver such highly functional lighting is through intelligent lighting systems, which can be remotely controlled to deliver a variety of effects and to adapt quickly to greater changes such as the reconfiguration of building spaces. There are at least two approaches to implementing such intelligent lighting grids: one gives the lights standalone power and then connects them to the building management system over a Bluetooth mesh; the other uses Power-over-Ethernet to provide both energy and control data to each light.
In another example of how interwoven the choice of connectivity strategies is becoming with the operation of buildings, some developers are considering using intelligent lighting to provide data links as well as functional lighting.
Li-Fi, enabled by modulating the lighting LEDs at high enough frequencies to carry valuable amounts of data without causing perceptible flicker, is regarded by some as an alternative to Wi-Fi. Some also claim that Li-Fi is more secure than Wi-Fi in some use cases.
Wired connectivity standards
Because intelligent buildings are expected to integrate so many different types of functionality, they often use heterogeneous connectivity strategies carried forward from other disciplines. Many traditional building-management systems use hierarchical connectivity, with a primary bus connecting highlevel building controllers to each other, and then secondary buses providing connections to lower-level controllers, I/O devices, and user interfaces.
Devices talk to each other over open protocols such as BACnet or LonTalk, and physical connectivity is provided in various ways, including optical fibre, Fieldbus or traditional Ethernet links, RS232 and RS485 serial connections, or specialised low-power, low-bandwidth wireless networks.
Advanced building management systems are moving towards using IP as a unifying protocol for all communications. Connectivity is then provided in a variety of ways, including fibre for building backbones, traditional Ethernet with power-over-Ethernet options, and wireless options including Wi-Fi, Li-Fi, Bluetooth, Zigbee and even 5G.
One emerging connectivity option is Single Pair Ethernet (SPE), a cut-down version of traditional Ethernet that uses a single twisted-pair for data transmission and features miniaturised connectors. SPE offers a dense, fast, quick-to-install and lower cost wired connectivity option than traditional Ethernet. SPE is defined in the IEEE standard 802.3cg-2019 amendment and specifies 10Mbit/s transmission over distances of up to 1,000m (10Base-T1L). Signals to this standard will need conversion to connect to 10/100/1000Base-T networks.
The SPE standard is supported with emerging SPE cable, connector, and channel-performance specifications. The new SPE connector, defined in IEC 63171-1, looks like the LC connector used for optical fibres and so is known as a ‘copper LC’. It will also be possible to deliver up to 50W over SPE, although the approach used is not compatible with current power-over-Ethernet infrastructure. Work is also underway to define how SPE should be used in structured cabling installations, enabling it to play a larger role in intelligent building infrastructure in the future.
Wireless connectivity
Many different protocols are being pressed into services to enable wireless connectivity in intelligent buildings. For example, the mesh-networking capabilities of Bluetooth LE make it easy to create ad hoc wireless networks among low-cost sensors installed in a smart building. Bluetooth’s beacon capabilities can also be used to provide building occupants with highly localised data services.
Multiple low-power wireless LAN technologies, such as Zigbee, can also be used to enable smart building functionality. As with wired connectivity, although it would be tidy to stick to a single standard, in practice intelligent buildings will probably have to implement multiple low-power WAN standards to support the use of a wide variety of functions such as sensors, lighting, and local controls.
One key standard for wireless connectivity within intelligent buildings will be IEEE802.11ax, commonly known as Wi-Fi 6. This uses the same frequencies and channel structure as previous Wi-Fi standards, but more sophisticated modulation schemes to enable higher data-rates over the same amount of radio spectrum. Wi-Fi 6 employs a multipath technique known as multi-user multiple-input multiple-output to enable each access point to handle eight simultaneous users, twice as many as supported by Wi-Fi 5. And beam-forming techniques will extend the reach of each router. Support for a technique called ‘target wake time’ will enable Wi-Fi 6 routers to tell devices when to wake and when to sleep, so that they can minimise their power consumption. As a side effect, having fewer devices polling the router will reduce radio interference, increasing its aggregate throughput.
This combination of features will make it easier for intelligent building designers to deliver high-bandwidth connectivity to transient populations of multiple users in busy locations from fewer routers. It will also make wireless connectivity a more capable connectivity option for semi-permanent infrastructure such as security cameras.
At the top of the wireless connectivity stack, in terms of capability and complexity, is the 5G cellular standard. This broadly drawn mobile communications standard offers higher bandwidth, lower latency and support for more devices per unit area served than previous cellular standards. The standard also includes two low-energy, low-datarate communications protocols that are formulated to support Internet of Things devices. The promise in 5G is that many intelligent building connectivity needs could, in theory, use equipment operating to a single umbrella standard.
Implementing 5G in buildings will involve the installation of multiple 5G signal repeaters, or a distributed antenna system that connects back to a centralised 5G basestation. Users will also have to decide whether they want to implement a private 5G network, or simply bring an external carrier’s network indoors. Propagation issues, especially with the millimetre-wave bands licensed for 5G in places such as the US, will also make it important to do proper radio planning to minimise interference among colocated wireless networks while maximising service to each user.
Conclusion
The premise of intelligent buildings is that, with the right communications, sensing and actuation infrastructure, buildings will evolve from being useful places for keeping out of the weather to sophisticated ‘machines for living’. This idealised vision would, of course, be enabled by leadingedge technology throughout and a single, heterogenous connectivity backbone.
In reality, today’s intelligent buildings have evolved from yesterday’s not-so-intelligent buildings, and so their functionality and connectivity will be implemented with a mix of existing and new technologies. Connectivity planning in this context, therefore, will be much more about ensuring peaceful coexistence between multiple standards than it will be about choosing the right clean-slate approach to work with.
This article was taken from the latest edition of Focus magazine. Click below to read the magazine in full, or alternatively, if you have a question about sensors for building automation you can get in touch with our team of technical specialists.
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