A decade ago, “smart building” was largely a marketing term. Sensors existed, controllers talked through proprietary wiring, and a skilled technician could coax useful data out of a system if he knew which menus to navigate. What has happened since is one of the quieter revolutions in the built environment — quiet because it happens inside walls and above ceilings, but consequential because buildings account for roughly 40 percent of global energy consumption.
2016 to 2018: The Language Problem
The building automation industry arrived in the IoT era with a foundational challenge: its devices could not easily communicate with one another, let alone with the broader internet. Three open international standards — KNX, LonWorks, and BACnet — had been developed for building automation, but alongside these, many manufacturers had developed proprietary protocols reserved exclusively for their devices. (MDPI, Generic IoT for Smart Buildings and Field-Level Automation, 2024)
You might have a Siemens controller managing HVAC on one floor and a Johnson Controls system handling lighting on another. Getting them to share data required custom integrations that were expensive and fragile. BACnet/IP became the bridge many practitioners turned to, but even that had its limits. Even when using BACnet, information could be wrapped in proprietary packets, denying other systems access to that data. Just because you could access a device’s data didn’t mean your interface could actually read it. (IoT For All, IoT Devices: A Sea of Change to the Building Automation Industry)
IoT protocols like MQTT began to enter the conversation, promising open, readable data transport to cloud platforms and analytics engines. The industry’s vocabulary began to shift — building managers began hearing “API,” “data historian,” and “analytics platform” alongside controllers and field devices.
2018 to 2020: Sensors Proliferate, Data Takes Shape
By 2018, sensor costs had fallen dramatically, wireless protocols like Zigbee and LoRaWAN had matured, and cloud storage had become affordable at scale. Connected sensors began monitoring temperature, humidity, occupancy, light levels, and energy usage in real time, feeding data into centralized platforms that allowed buildings to sense and respond to changing conditions automatically. (Neuroject, Top 7 IoT Building Automation Trends, 2025)
The first commercially viable fault detection and diagnostics software emerged. Rather than waiting for a chiller to fail or an energy bill to spike, operators could receive alerts when a VAV box was hunting or a damper was stuck. Lighting, humidity, and air quality were increasingly recognized as crucial to occupant productivity and well-being, and wireless IoT sensors became the instruments to maintain that environment. (Infraspeak, How IoT is Reforming Building Automation, 2024)
The challenge was no longer collecting data — it was making sense of it. Analytics platforms began applying rule-based logic and early machine learning to surface signals from the noise.
2020 to 2022: The Pandemic Accelerates Everything
No event reshaped building operations as suddenly as COVID-19. Social distancing, occupancy tracking, smart HVAC, and stricter cleaning requirements significantly increased the importance and demand for IoT in buildings, because smart buildings could enable more efficient facilities management and support a safe, healthy environment. (Umair et al., Impact of COVID-19 on IoT Adoption in Smart Buildings, MDPI Sensors, 2021)
This gave rise to novel use cases — remote occupancy monitoring, automated HVAC optimization, and predictive asset maintenance — that helped employers save costs and demonstrate compliance, while creating a new wave of IoT adopters, including owners of legacy buildings. (IoT For All, Comparing Pre & Post COVID IoT Deployments in Smart Buildings, 2022)
IT and operational technology moved closer together as companies limited on-site staff and defaulted to remote monitoring. While this provided real benefits, it also merged vulnerable OT systems with more mature IT infrastructure — and, long treated as a background concern, cybersecurity became urgent almost overnight. (ISA Interchange, IoT Security in the COVID-19 Pandemic, 2021)
2022 to 2024: AI Enters the Control Loop
With data infrastructure in place and cloud connectivity normalized, the industry shifted from collecting information to acting on it intelligently. AI and machine learning became game-changers — by analyzing sensor data on equipment performance including vibrations, temperature, and runtime, AI could predict failures or inefficiencies before they occurred. (Neuroject, Top 7 IoT Building Automation Trends, 2025)
Rather than alerting a human and waiting for a response, systems began executing corrective actions autonomously. HVAC setpoints adjusted on predicted occupancy and weather. Energy management systems shed loads during grid peak periods without manual intervention. Siemens launched Building X as a cloud-based, open platform, while Accenture and Johnson Controls announced OpenBlue Innovation Centers advancing AI, digital twins, IoT, and cloud computing in building operations. (Markets and Data, United States Building Automation System Market, 2023)
Edge computing also gained serious traction — local decisions made in milliseconds, critical for safety systems and latency-sensitive control, where round-trips to the cloud are not acceptable. This is the era where the concept of the closed-loop autonomous building stopped being theoretical.
2025 to 2026: The Feedback Loop Closes
Today’s leading building automation systems are genuinely autonomous in ways that would have seemed ambitious five years ago. The OT-AI relationship has matured from data collection into something closer to a nervous system — sensors feed AI, AI decides, actuators act, sensors confirm, AI improves. Continuously, with progressively less human intervention.
Europe’s smart building market has grown from roughly $6.3 billion in 2024 to a projected $7.5 billion in 2025, on track to reach $31 billion by 2033. (Neuroject, IoT Building Automation Systems: 2025 Ultimate Guide) The U.S. market reached $24.66 billion in 2024 and is projected at $68.67 billion by 2034. (Precedence Research, Smart Building Market Size, 2025) The industry valued at $6.65 billion globally in 2016 is now one of commercial technology’s more consequential growth sectors. (ReportsnReports, Smart Building Market Forecast, 2018)
Sustainability has become the defining operational pressure. Carbon accounting is now a real-time function, not an annual report. Buildings are beginning to actively participate in energy markets rather than passively consuming from the grid. Cybersecurity has matured in parallel — when BACnet/IP was first introduced, no passwords were required to access building automation devices. (NECA, Smart Buildings and IoT Impact on Electrical Contracting) That era is over. Modern deployments treat control networks with the same discipline as enterprise IT.
What Comes Next
The trajectory is clear even where precise timing is not.
Digital twins move from demonstration to standard practice for large portfolios. Simulate a setpoint change or retrofit investment before executing it — the cost and risk of optimization drops substantially.
Edge AI keeps pushing intelligence closer to the action. Latency and bandwidth constraints are shrinking steadily. Within a few years, routine building decisions will happen locally; cloud infrastructure will handle learning, benchmarking, and portfolio analytics.
Grid integration deepens considerably. Buildings are flexible, controllable assets capable of providing real grid services. As renewables grow and grid intermittency increases, that flexibility becomes genuinely valuable — and building automation systems will be the mechanism for capturing it.
Open standards approach resolution. Semantic data models like BRICK Schema and cloud-native APIs enable building intelligence to be composed from best-of-breed components rather than committing to a single vendor’s ecosystem.
The building of 2030 will not look different from the outside. Inside, an intelligence will be managing its energy, air, occupant experience, and grid relationship in ways today’s best systems are only beginning to approximate. Ten years ago, that building was an aspiration. Today, its foundations are substantially in place
From the AutomatedBuildings.com Archive — Further Reading
The following articles from the AutomatedBuildings.com archive provide context and depth for the 2020 to 2022 period covered in this post.
“When AI and IoT Meet” AutomatedBuildings.com, June 2022 automatedbuildings.com/news/jun22/articles/biot/220526123101biot.html
Published at the inflection point between the pandemic era and the AI era, this article captures the moment when the industry began connecting its newly expanded IoT infrastructure to machine intelligence. Heightened concerns about climate change and rising energy costs had increased the need for building systems to take full advantage of AI and IoT devices, with the combination better equipping building operators to analyze and optimize energy efficiency data — encouraging IoT devices to act intelligently with minimal human intervention. Automatedbuildings A practical, grounded read for facility managers trying to understand where sensor data actually goes once it leaves the floor.
“IoT for Smart Buildings Isn’t What You Think It Is” AutomatedBuildings.com, February 2018 automatedbuildings.com/news/feb18/articles/iotforall/180116105505iotforall.html
Written just before the pandemic reshaped every assumption about building occupancy, this article is worth reading in retrospect. The HVAC, lighting, fire protection, and other systems work on their own — directly reading inputs and controlling outputs to keep a building comfortable and secure. The question posed was why a facility manager should care about the Internet of Things when virtually all existing buildings operated just fine when not connected to any external network. Automatedbuildings COVID-19 answered that question definitively two years later. Remote monitoring, air quality tracking, and occupancy management suddenly moved from optional to essential — and the buildings that had already invested in IoT infrastructure were the ones that adapted fastest.
IoT Opens to Mobile Messaging Standards — The Direction Is Toward Open Standards @therese Sullivan, — Contributing Editor, AutomatedBuildings.com | April 2014 @tridium
Writing a full six years before the pandemic forced the industry’s hand on remote connectivity, Therese Sullivan identified MQTT’s publish/subscribe architecture as the missing link between building automation and the broader Internet of Things. Her analysis — tracing MQTT from its IBM origins through Eclipse Foundation adoption and into real-world sensor network applications — proved prescient. The lightweight messaging standard she championed here became a foundational layer of the cloud-connected building platforms that defined the 2020–2024 era. Essential background reading for anyone asking how buildings learned to talk to the internet.
Six years before remote connectivity became urgent, Sullivan identified MQTT’s publish/subscribe architecture as the missing link between building automation and the IoT. The lightweight messaging standard she championed here became foundational to the cloud-connected platforms that defined the 2020–2024 era.
