Building Management Systems: Functions and Integration

A building management system collects and manages information from connected building services and supports coordinated operation. Through information exchange, it can issue commands to equipment according to the approved operating strategy, while supporting technical performance, safety and security.

A BMS can integrate monitoring and appropriate control of building services such as:

• Heating, ventilation and air conditioning.
• Security systems.
• Lighting controls.
• Energy metering.
• Lifts.
• Electrical systems.
• Fire-protection systems, through approved interfaces and without overriding their dedicated safety controls.

The integration scope varies with the project and may include more or fewer systems than this illustrative list.

A BMS can be designed for high availability. For example, an optional redundant-server arrangement allows a second server to take over if the first fails. This is a design choice, not a feature of every BMS. Data-retention periods, backup arrangements and recovery procedures are configured according to the project’s requirements.

Building-management software can provide the following functions:

Information collection

• Collect environmental measurements, equipment status, system operating information and data needed to coordinate connected services.
• Store and process the information for the retention period required by building management.

Monitoring and alarms

• Provide graphical displays for technical warnings and alarms. Faults reported by connected equipment and systems can be displayed for the operator.
• Provide audible alerts to notify operators who are not watching the display.

System management

• Allow authorised operators to extend the configured system, for example by adding equipment and control points, subject to the platform’s capacity and licensing.

Control

• Operate equipment through graphical interfaces showing equipment images or building floor plans.
• Use authorised graphical control points to issue commands such as On, Off or Disable where the equipment and safety strategy permit.
• Schedule automatic operation to match the building’s weekly, monthly or annual activities and reduce unnecessary energy use. When activities change, an authorised operator can revise or remove the relevant schedules.

Access control and operating records

• Assign different monitoring and control permissions to operators according to their responsibilities, applications and equipment.
• Record operator access, the time of actions and equipment commands in the system’s audit trail.
• A BMS may use distributed building controllers for different applications. Storage, programme retention and backup-power capabilities depend on the selected hardware. An example configuration uses a 100BASE LAN and TCP/IP links between central servers and control panels to download programmes.
• During a communications failure, suitably configured controllers can retain settings and log selected measurements such as temperature, humidity and pressure. Retention during a power failure depends on memory, backup power and product specifications; uninterrupted recording cannot be assumed.
• Authorised personnel may access compatible controllers locally using approved tools and credentials. Where supported, local operation can continue during a BMS network interruption.
• Suitable interfaces or gateways enable integration with other systems using protocols such as BACnet and Modbus.

Building controllers can monitor and, where appropriate, control the following equipment:

• Electrical systems
  • Transformers.
  • Standby generators.
  • Main and floor-level distribution boards.
  • Uninterruptible power supplies (UPS).
• HVAC systems
  • Chillers.
  • Chilled-water pumps.
  • Cooling towers.
  • Air-handling units (AHUs).
• Extract fans.
• Staircase pressurisation-fan status and approved operating interfaces.
• Fire-pump operating status and approved interfaces.
• Readiness indicators for gaseous fire-suppression systems.
• Alarm signals received from the dedicated fire-alarm panel.
• Interfaces with building security systems.
• Interfaces with lift systems to monitor operating status and car position from the central control room.

Controllers are installed in appropriate plant or technical rooms: electrical controllers in electrical rooms, and HVAC controllers in mechanical plant rooms, for example.

Integrating building services provides operators with a clearer view of technical systems and supports coordinated management, improved operation and potential reductions in operating costs.