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Smart building OT: Buying new vs. Retrofitting old

March 24, 2022
One way to get around the need to purchase new OT systems for IT/OT convergence is to retrofit them with specialized hardware and software that allow them to operate over a typical LAN.

The convergence of information technology (IT) and operational technology (OT) onto a single unified network is a trend that’s being driven by the hopes of lower overall operating costs, ease of management and uniform cybersecurity enforcement.

Now that the time for convergence has arrived, however, building owners are finding that several of their legacy OT systems cannot natively connect or communicate over IP-based networks.

One way to get around the need to purchase new OT systems for IT/OT convergence is to retrofit them with specialized hardware and software that allow them to operate over a typical LAN. Let’s look at what this entails and the pros and cons of retrofitting OT versus buying new.

What legacy building OT systems can be retrofitted?

OT equipment and platforms within commercial properties often consist of HVAC, lighting, elevators surveillance/access control, occupancy health and physical safety systems. As with all digital transformation projects, if these OT platforms can be centrally managed and automated, several cost savings efficiencies and an overall increase in positive occupancy experience can be gained.

However, to accomplish these smart building digital transformation goals, these OT components must be accessible from the in-building IP network.

In certain cases, legacy OT systems are still in place within commercial properties – many of which use proprietary or non-IP communications protocols that cannot be transported across a typical IP-based LAN. Common communication protocol examples include Bluetooth LE (BLE), LORA, Sigfox and Zigbee.

That said, the fact that one or more of these legacy OT systems can communicate and be managed remotely using these types of protocols is a key indicator that they can be retrofitted to operate on more modern IP-based wired and/or wireless LANs.

How are legacy building OT systems retrofitted?

Due to differing communication protocols being used by older OT systems, a process must occur that either encapsulates non-IP protocol traffic into IP -- or one that directly translates non-IP comms into IP.

The first option is useful in situations where the management platform is also only capable of interacting with and controlling various OT device endpoints using a non-IP communications protocol. Thus, the IP network in this situation is used as a basic transport backhaul. The benefit of this retrofit model resides in the fact that a unified network for both IT and OT can be utilized, eliminating the need for multiple air-gapped networks to exist. The downside of this option, however, is that OT remains in a communications silo – making it impossible to manage these systems from a centralized smart building OT management platform.

A second popular method is to place protocol translation gateways in front of OT devices. This option effectively converts other popular protocols used by legacy OT systems and turns them into IP. Doing so opens the door to the ability for OT to be controlled and monitored by third-party and centralized OT management platforms. The caveat, however, is that the legacy protocol must be supported and some management/automation functions that operate natively may not work once the communications are converted to IP.

Why buy new when you can retrofit?

According to several vendors that offer OT retrofitting platforms and gateways, the upfront capital expenditure savings gained when retrofitting existing OT as opposed to replacing them with natively speaking units is in the ballpark of 50-80% depending on the type of OT in question.

While these cost savings figures are significant, one must also consider the potential drawbacks. For one, retrofitted OT systems often lose certain functionalities when it comes to automations and integrations with other smart building platform. In some use-case situations, basic management and automation capabilities my not be enough.

Second, understand that the gateways and software-defined processes required to retrofit systems for usability on IP-based networks make troubleshooting and management a more cumbersome ordeal. Thus, while CAPEX may be lower when retrofitting, expect ongoing operational expenditures (OPEX) to be higher due to an increase in operational management complexity.

The ultimate decision on whether to retrofit or replace with new OT systems will largely come down to the goals of the smart building digital transformation project and whether the benefits of a retrofitted system can meet those goals. In most cases, a building can be retrofitted with basic OT component metering, management and automation processes put in place.

Then, once the OT equipment finally does reach the end of its useful lifecycle, the systems can be replaced with IP-native OT hardware and software.

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About the Author

Andrew Froehlich | Contributor

As a highly regarded network architect and trusted IT consultant with worldwide contacts, Andrew Froehlich counts over two decades of experience and possesses multiple industry certifications in the field of enterprise networking. Andrew is the founder and president of Colorado-based West Gate Networks, which specializes in enterprise network architectures and data center build-outs. He’s also the founder of an enterprise IT research and analysis firm, InfraMomentum. As the author of two Cisco certification study guides published by Sybex, he is a regular contributor to multiple enterprise IT-related websites and trade journals with insights into rapidly changing developments in the IT industry.

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