What is Building Management System?

Introduction

Building Management Systems (BMS) also known as Building Automation Systems (BAS), Building Management and Control System (BMCS).

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.

Building Management System or BMS is normally used in a high-rise building that has a number of MEP types of equipment like chillers, AHUs, VAV, Lightings, Electrical panels, pumps, Firefighting equipment, etc. It becomes very difficult to operate, maintain and commission all of them physically and would require a huge manpower resource.  Which increases the cost burden on the owner. The HVAC components are responsible for maintaining the human comfort of the building, the chillers should maintain the temperature of the supplying water at a certain degree Celsius so as to maintain the human comfort at the desired level. All the above-mentioned equipment should be well coordinated to achieve maximum efficiency and functionality.

 Without a well-coordinated system. The efficiency would be at stake. The technicians and the field working team won’t know which equipment has stopped working and need a replacement or repair in order to function at its utmost efficiency.

In such conditions, a Building Management System (BMS) comes into the picture. It is a computer-based control system that controls and monitors buildings Mechanical, Electrical, Plumbing, Firefighting, Security system equipment’s all from a single room. Which makes it easier to identify the problems.

Building Management Systems are most commonly implemented in large projects with extensive mechanical, electrical, HVAC systems. All these systems are linked to BMS which use a large amount of energy. BMS systems are critical components to manage energy demands. Improper configuration can lead to energy wastage.

What Does a BMS Do?

1. The role of the BMS in day to day building operation

• The most common primary function of the BMS is the control of a buildings Heating, Ventilation and Air Conditioning Systems (HVAC) including-Air Handling Units, Chilled Water Plant, Cooling Towers, Tenant Condenser Water, Heating Water Plant Exhaust Systems.
• Control of Building Systems and Services
• 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

2. Building Control Applications

Building control applications include for 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 air flow / pressure control
• Main Plant Chiller and Boiler sequencing
• Toilet, car park, kitchen and general exhaust fan control
• After Hours Building Control

3. Measuring and Monitoring Building Performance

• Operator Interfaces including Graphical User Interface (GUI) for monitoring and adjustments
• Trend data is important when determining the stability of control algorithms and when tuning the system.
• Reports are pivotal when demonstrating building performance against sustainability targets such as NABERS.
• Equipment alarm and fault notification, reduces down time and consequential impact

4. Interaction With Other Building Systems

There are 3 major levels 

1. Field Level – here all the equipment’s like sensors, actuators, valves, thermostats are included it holds the important level in BMS system. As the actions taken by the BMS systems is totally dependent on the inputs from this field devices.
2. Automation Level – it has compact modules with programmable PLC, relays, ddc panels, etc. it takes the input from the field devices and maintain the occupant comfort as per the set points.
3. Management Level – here the working of all the major equipment is represented in a graphical format. It displays all the information taken from the field level. Use to control and monitor the equipment’s from the single room through PCs or HMIs

The field devices are hardwired to the DDC panel, the DDC panels which include the plc are connected to the BACnet ethernet cable. The automation levels are connected to BMS levels via the BACnet IP protocol.

Communication used in BMS

1. BACnet – stands for Building Automation Control network. It is developed by ASHRAE. The main objective was to achieve interoperability between building systems from different manufacturers.

2. Lonworks– Local Operating Network, it is the 2^nd widely used protocol created by echelon corp in 1988. Designed to work on low bandwidth, for networking devices through power lines, fiber optics, and other media.

3. Modbus -Modbus is a serial communication protocol developed by Modicon published by Modicon® in 1979 for use with its programmable logic controllers (PLCs). In simple terms, it is a method used for transmitting information over serial lines between electronic devices. The device requesting the information is called the Modbus Master and the devices supplying information are Modbus Slaves.

Advantages of BMS

1. Simple user interface- it provides a simple interface with all the operating values and inner components which makes it easier to control and monitor the equipment’s from one place.
2. Alarm management – it provide minor and major alarms for hvac equipment’s, smoke detection, lighting which helps in exactly identifying the device wanting repair or replacement.
3. Timely scheduling- we can schedule the operation of equipment’s to run for a particular time based on the human occupancy in the particular area.