INTERNET OF THINGS
For small-scale operations, this approach can be workable, but will generally create extra supplier-management overheads. It can also lead to inefficient ‘swivel chair’ integration, as facilities staff attempt to manually manage numerous SIMs on different operating platforms, with different contracts from multiple suppliers.
When it comes to retrofit connectivity in HVAC systems, the best option is usually wireless. This generally works well as the low frequencies used in most formats are chosen for their ability to easily penetrate walls and common obstructions. Sometimes it can be beneficial to use a meshing protocol such as Zigbee, which allows each sensor to relay data to and from its nearest neighbour. Once the data reaches the gateway, the 3G or 4G connection is best maintained using a multi-network or ‘roaming’ SIM card to increase resilience and coverage. It’s worth noting that although many of the major network operators do now offer IoT clients a multi-network option, these are generally steered to the operator’s home network. A priority list determines the order in which different networks are tried if signal is lost.
Also, IoT devices are generally configured to use GSM voice as a proxy measure of signal strength (like the bars on a mobile phone),
although a strong signal does not guarantee that 3G or 4G data is available. The best workaround is for engineers to configure the device to check for 3G or 4G data availability, following a GSM attach, using this metric for network selection.
Security
Security is fundamentally important for every connected HVAC or refrigeration system, especially since networks of this kind are often targeted by cybercriminals.
When it comes to IoT projects, each company needs to find an appropriate level of network security – one which minimises cybersecurity threats, as well as potential connectivity obstruction. This depends on a number of factors, all of which vary by organisation and particular circumstance.
An internet protocol security (IPSec) virtual private network (VPN) helps ensure that communication between devices and the servers is fully encrypted and the IP address range remains private. Further steps include deploying an edge security system where data is encrypted on the sensor device, before being transmitted for storage.
IoT connectivity also has an increasing role to play in another kind of security – helping
companies protect their engineers. In the HVAC industry, installers and technicians frequently work in field and on plant-based jobs alone. Here they are exposed to risks such as falls from height and other ‘worker down’ scenarios, as well as unforeseen situations during travel to jobs. Lone Worker Solutions uses our connectivity in its range of wearable, mobile and app- based safety systems. HVAC engineers and their employers can use them to maintain uninterrupted fall/worker down detection as well as voice, text and button-activated alarm links with a dedicated 24-hour alarm centre.
Looking ahead
The HVAC connectivity option of the near future is NarrowBand IoT (NB-IoT), which uses the 2G spectrum to offer improved indoor reach and building penetration versus 3G and 4G. It also promises a lower power drain on devices, similar to other LPWA alternatives, offering longer battery life for situations where there is no accessible power supply.
NB-IoT pricing will fall to the point that it becomes too cost effective to ignore. It is a simpler and more powerful alternative to hub and spoke, or meshed, short-range wireless or any of the current LPWA services.
www.acr-news.com
March 2019 23
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