Smart buildings are rapidly becoming the norm rather than the exception. However, when it comes to operational technology (OT) such as Building Automation Systems (BAS), HVAC, smart lighting, energy management systems, and fire detection/life safety systems, serious concerns about a lack of built-in security can compromise OT devices. Once compromised, attackers can move laterally to disrupt other operations, often resulting in data theft or loss. The best way to address these issues in 2026 is to adopt a Zero Trust approach that uses a “never trust, always verify” methodology, protecting OT devices directly at the network level.

Inherent Vulnerabilities of OT in Smart Buildings

While smart buildings have been proven to deliver impressive gains in terms of operational efficiency and occupant comfort, legacy (and even some modern) OT platforms were not designed with cybersecurity in mind. These realities create persistent vulnerabilities, including:

• Slow firmware update cycles: Compared to IT systems, OT devices often have multi-year firmware update cycles, leaving these systems vulnerable to emerging threats.
• Inability to use traditional security agents: Many OT controllers and embedded systems lack the processing power, memory, and OS needed to run endpoint detection tools.
• Insecure legacy protocols: Proprietary and standards-based protocols commonly found in OT frequently lack end-to-end encryption, authentication, or validation checks that are standard with IT systems.
• Weak access controls: OT systems often ship with default passwords, open ports, and limited logging capabilities. If these default settings remain unchanged, attackers can easily gain access, move laterally across the network, and maintain persistence with little chance of detection.

These built-in limitations clearly show why a Zero Trust approach is particularly well-suited to protecting OT and all other connected devices that share the same network.

Addressing OT Vulnerabilities with Zero Trust

Zero Trust offers a fundamentally different security model that is well suited to the inherent security flaws of smart building OT. Instead of relying on perimeter-based security that only protects threats from the outside while allowing traffic inside the network to go unfettered with implicit trust, Zero Trust does the following:

• Enables strong device fingerprinting and authentication that work with legacy OT systems.
• Requires continuous verification of every device access request inside the network.
• Enforces least-privilege access through network-based policies so that compromised devices cannot scan or potentially compromise other devices on the internal network.
• Supports continuous monitoring and anomaly detection that increases the ability for security teams to monitor OT systems.

By shifting the focus to device identity, context, and operational behavior, Zero Trust significantly reduces the attack surface and limits the impact of a breach, even for OT.

How to Implement a Zero Trust Framework for Smart Building OT

The good news is that adopting a Zero Trust framework doesn’t require a complete overhaul of your existing OT infrastructure. Instead, it can be implemented seamlessly using a phased approach that won’t impact operational and safety requirements.

The process starts with providing an accurate inventory of all OT devices within a smart building network. Popular tools include Nozomi Networks, Claroty, Dragos, and Armis, which are specifically designed for OT and building automation systems. Once an inventory and real-time visibility are established, network segmentation planning can begin, which creates secure zones using network policies that contain lateral movement and limit most threats such as unauthorized device scanning and ransomware propagation.

The next step in the process is to strengthen identity and access controls for OT devices by implementing device fingerprinting, certificate-based authentication, and least-privilege policies. Continuous behavioral monitoring should also be implemented here to establish baselines for normal operating behavior, and to flag changes to this behavior that could indicate a breach. Many of the same platforms used for initial device visibility and inventory can also support these capabilities.

Finally, secure remote access should be addressed, as many OT systems rely on vendor-driven remote access capabilities for management and maintenance. These remote sessions should be reworked to a Zero Trust model using just-in-time access approval, multi-factor authentication, and other common security features that restrict vendor access to only specific systems and maintenance windows.

Building a more Secure OT Future with Zero Trust

Keep in mind that Zero Trust for OT delivers more than just risk reduction for sensitive data and apps. It also minimizes costly downtime from breaches, simplifies cybersecurity compliance policies, and can lower cyber insurance premiums. In 2026, building owners and operators who treat Zero Trust as a strategic enabler as opposed to just another security project can gain a competitive advantage through more resilient, efficient, and future-proof buildings.

Next Steps for Owners, FMs, and Tech Integrators

• Create a complete OT inventory that includes BAS, HVAC, lighting, energy management, access control, and life safety systems connected to the building network.
• Identify high-risk vulnerabilities such as default passwords, open ports, outdated firmware, insecure protocols, weak logging, and unnecessary network connections.
• Segment building systems into secure zones to limit device-to-device communication and reduce the risk of lateral movement if one system is compromised.
• Apply least-privilege access controls using device fingerprinting, certificate-based authentication, continuous verification, and role-based permissions.
• Strengthen vendor remote access with multi-factor authentication, just-in-time approval, limited maintenance windows, and system-specific access.
• Implement continuous monitoring and anomaly detection to establish normal operating baselines, flag suspicious behavior, and improve long-term OT resilience.