Consider a building with devices like energy meters, occupancy sensors, room thermostats, and pressure monitors. These sensors supply a Building Management System (BMS) with crucial data, alerts, and status updates. The BMS functions across three distinct levels, integrating sensors, actuators, controllers, and management interfaces to enhance building performance.
Field level: At this level, there are sensors (like those for temperature and air quality) and actuators (such as light switches, blinds, and ventilation flaps). Systems like KNX, BACnet, and Modbus are commonly used here.
Automation level: This middle layer hosts controllers and I/O modules that process data and execute controls for various systems, such as HVAC and temperature regulation. It follows the principles of Metering, Control, and Regulation (MCR).
Management level: The top layer provides the interface for facility managers and operators, typically through web-based platforms. This level allows users to input commands that the BMS then translates into actions at the field level.
A command from the management level can trigger adjustments in HVAC settings, lighting, or equipment operation modes, showcasing the BMS’s role in optimizing building functionality.
Wired systems, LoRaWAN, and cellular gateways
The architecture of a BMS can vary significantly depending on the building’s age and technological infrastructure. Sensors and actuators within the system can be connected via wired systems, LoRaWAN technology, or cellular gateways.
Wired sensors
Wired sensors communicate through physical cables, integrated directly into the building’s infrastructure and connected to a central control system. These sensors typically use protocols such as KNX, BACnet, M-Bus, and other fieldbus standards.
Advantages of wired sensors:
- Reliability: Wired connections provide consistent performance and real-time data with minimal latency
- Interference: Lower risk of signal interference compared to wireless systems
- Existing infrastructure: Utilizes already established cabling
Disadvantages of wired sensors:
- Installation costs: High labor and material costs, especially for retrofitting older buildings
- Inflexibility: Limited scalability due to the fixed nature of cable installations
LoRaWAN sensors
LoRaWAN sensors are wireless devices that use the LoRaWAN protocol, designed for low-power, long-range communication. These sensors are particularly suited for IoT applications within buildings.
Advantages of LoRaWAN sensors:
- Scalability: Eliminates the need for extensive cabling, reducing installation costs and complexity
Disadvantages of LoRaWAN sensors:
- Range: LoRaWAN sensors may have limitations regarding data transmission range, especially in buildings with thick walls
- Battery life: Battery is also a consideration, as it determines the maintenance requirements for replacements
Cellular gateways
In some BMS setups, cellular gateways are used to connect sensors and actuators. These gateways provide an alternative means of communication, especially useful in areas where wired infrastructure or LoRaWAN coverage is impractical.
Advantages of cellular gateways:
- Scalability: Cellular gateways are easily scalable
- Coverage: Cellular gateways offer broader coverage and higher bandwidth compared to LoRaWAN
Disadvantages of cellular gateways:
- Connectivity: Potentially higher latency compared to wired connections, depending on network conditions
Integrating existing BMS with an IoT platform
By connecting an existing BMS to an IoT platform, facility managers and building owners gain a centralized view of all building data, seamlessly integrating both wired BMS and wireless, battery-powered devices. This unified data hub enables data-driven decision-making, providing a holistic view of building performance where insights from diverse sources come together in one place.
