BMS systems are “Intelligent” microprocessor-based controller networks installed to monitor and control a building’s technical systems and services such as air conditioning, ventilation, lighting, and hydraulics. More specifically, they link the functionality of individual pieces of building equipment so that they operate as one complete integrated system.

Now installed in every major building or facility with the availability of direct integration into all other building services such as security, access control, CCTV, fire, Lifts and other life and safety systems. Current generation BMS systems are now based on open communications protocols and are WEB enabled allowing integration of systems from multiple system vendors and access from anywhere in the world.

Terminology and acronyms:

  • Building Management Systems (BMS) also known as Building Automation Systems (BAS)
  • Building Management and Control System (BMCS)
  • Direct Digital Controls (DDC) and Building Controls.

Other terms associated with Control Systems include:

  • Supervisory, Control and Data Acquisition (SCADA)
  • Programmable Logic Controllers (PLC)
  • Energy Management System (EMS)
  • Data gathering panels (DGP)
  • Modbus, Lonworks, and Bacnet – All refer to communications protocols
  • ‘Front End’ – a legacy term used to refer to the BMS Operator Workstation


  • It should allow the owner to set up schedules of operation for the equipment and lighting systems so that energy savings can be realized when the building or spaces in the building are unoccupied.
  • It should have the ability to monitor energy usage including the ability to meter electric, gas, water, steam, hot water, chilled water, and fuel oil services.
  • It should offer the ability to send alarms via email, pager, or telephone to alert building managers and/or technicians of developing problems and system failures.
  • Likewise, it should have trim and respond based on zone demand the set point for various heating and cooling sources will change according to demand from the zones. In a VAV system, all the VAV boxes are served from a central air handling unit.
  • It should have such BAS control algorithms as reset schedules for heating plants, static pressure control, and other systems where energy savings can be realized through these predictive programs.
  • In conjunction with the appropriate mechanical system, the set-up should offer economizing based on enthalpy calculations and/or CO2 set point control.
  • It should allow the system to compare space temperature, outside air conditions, and equipment capabilities so that the equipment can be turned on at an appropriate time to ensure space set points are achieved before occupation.
  • It should have the communications abilities to be integrated with other building automation control systems and TCP/IP. BACnet compatible or other open-source communication protocol is a plus.

Building control applications include for the following:

  • Zone temperature monitoring and control
  • Zone Variable Air Volume (VAV) control to zones
  • Zone CO2 monitoring and control (Air Quality)
  • Air handling unit supply air temperature control
  • Air handling unit supply airflow/pressure control
  • Main Plant Chiller and Boiler sequencing
  • Toilet, car park, kitchen, and general exhaust fan control
  • After-Hours Building Control

Application domains:

  • Event centers
  • Schools / Universities
  • Office Buildings
  • Shopping Malls
  • Stadiums
  • Hospitals

Building management systems help building managers understand how buildings are operating and allow them to control and adjust systems to optimize their performance. As well as collating data and allowing ease of control, BMS can help; visualize data, automatically generate reports and create alarms and alerts when parameters are exceeded, failures occur, or with prognostic systems, when failures are likely to occur. They can also allow comparison between spaces, buildings, and benchmark data.

Intelligent building management systems bring together information and controls relating to a number of different systems operating using a range of different software applications and allow them to be controlled form single interface. This makes monitoring and analysis more straightforward and comprehensive and allows information from one system to influence the controls for another.

The most common primary function of the BMS system is the control of a building’s Heating, Ventilation, and Air Conditioning Systems (HVAC) including:

  • Air Handling Units
  • Chilled Water Plant
  • Cooling Towers
  • Tenant Condenser Water
  • Heating Water Plant
  • Exhaust Systems
  • Zone Controls
  • Computer Room AC


The day-to-day role of the BMS:

  • Control of Building Systems and Services
  • Graphic User Interface (GUI)
  • Real-Time Monitoring of Building Operation and Performance
  • Trending and Logging of Building Operation and Performance
  • Time Scheduling of Building Systems
  • Fault Management and Alarming
  • Control Application Programming
  • User Event Management
  • Energy Management and Reporting (NABERS)

BMS may also be used to monitor and control power distribution, energy consumption and uninterrupted power supplies (UPS) and may be referred to as building energy management systems (BEMS).

Building Automation Systems.

Lighting control

As BAS works with mechanical systems, BAS can also be integrated with electrical systems such as lighting. In a typical campus environment or office buildings, there are typical times of high occupancy. During these times you want the lighting systems to work normally. After hours, when everyone has gone home, you want the lights to be off. Some people forget or haphazardly leave lights on. When a BAS system is integrated into the lighting system, time can be programmed into the system to turn the lights off for most of the building.

ADVANTAGES OF BMS  Vs Stand-Alone Control

The effectiveness of the BMS system will depend on the range and quality of the information it receives from sensors and the programming of how this information is used. For example, information about external and internal conditions can be used to determine the level of heating required so that a plant can be activated and a building pre-heated before occupants arrive.

Building Automation Systems

HVAC Control

Modern buildings typically have central HVAC plants to provide heating and cooling for the entire building. Some high-rise buildings can have several central plants either in the basement, on various floors, or on the roof of the building. Institutional buildings also, to some degree, have central plants that provide heating and cooling for the buildings that are spread out over campus. In the old days, before building automation systems, these systems were not integrated.

Building automation systems or BAS offered all these systems to be integrated and offered precise control based on several factors including weather conditions, demand factors of occupation, and other variables down to the micro-level that allows for the systems to be very energy efficient.

BAS Integration for HVAC Systems.

Many people wonder what Building Automation Systems (BAS) can do. BAS is mainly used in commercial HVAC control systems and energy management system applications. Building Automation itself is an energy management system that saves management companies and building owners by efficiently controlling air conditioning and heating comfort and process systems.

BAS is where mechanical and electrical systems and equipment are joined with microprocessors that communicate with each other and possibly to a computer. This computer and controllers in the building automation system can be networked to the internet or serve as a stand-alone system for the local peer-to-peer controller network only. In addition, the BAS controllers themselves do not need a computer to process the control functions, as the controllers have their own internal processors.

Improved Tenant Comfort Air Conditions:

  • Real-time monitoring of tenant conditions
  • Greater load-based control strategies
  • Trend data of performance, improved fault-finding
  • Air quality management (CO2)
  • After hours operational requests, tenant billing
  • Alarm notifications of faults reduce downtime
  • Automated changeover of failed equipment

In some of the strictest definitions, air conditioning is used to describe systems that control the moisture content of air, that is, its humidity. This can include humidification and dehumidification. Humidity control can be important for; the comfort of building occupants, to reduce the incidence of condensation (both surface and interstitial), for specialist environments such as swimming pools, and where the protection of sensitive items requires particular conditions.

Air conditioning involves full control over the humidity within the conditioned space as well as temperature control.

HVAC is one of the biggest energy-consuming equipment and needs to work efficiently.

Heating Ventilation and Air Conditioning (HVAC) is generally responsible for a significant proportion of total building energy consumption. A typical system accounts for approximately 40% of total building consumption and 70% of base building.