A building management system (BMS) is an electronic network used to monitor and control a building’s electrical and mechanical services, including heating, ventilation and air conditioning (HVAC), and lighting. A BMS can incorporate wider building services such as security, access control, elevator and safety systems. Depending on specific application and configuration, a BMS may be known by other names including a building automation systems (BAS), building management and control system (BMCS), and a building energy management systems (BEMS).
A BMS gives owners and operators automated precision to optimise the performance and energy efficiency of their buildings from a single, intuitive digital interface. Installing a modern BMS enables occupant comfort to be delivered consistently and for the lowest possible energy use, delivering savings, improved productivity and reduced greenhouse gas emissions.
A BMS can be procured as a complete, engineered package or implemented as a means to integrate existing systems. Modern BMS applications are based on open communications protocols and are web-enabled, allowing integration of systems from multiple system vendors.
Benefits of a BMS
Compared with multiple separate control systems, a BMS offers centralised control, greater flexibility, increased interaction and feedback. Replacing separate control systems with a BMS can provide a cost-effective energy saving opportunity, while delivering a range of other benefits. The US Department of Energy and other researchers have shown that proper tuning with a BMS can deliver 17 to 30% energy cost savings compared to typical buildings without a BMS.
A BMS older than 10 years is likely to benefit from an upgrade or replacement, especially if the software and components are no longer replaceable or supported by the vendor. Other reasons to consider upgrading include reliability issues, poor condition of components, lack of web compatibility, difficulty with incorporating new equipment and sensors, and whether the system can perform energy monitoring and reporting. A new BMS should be an essential consideration of any major building fit-out or plant upgrade.
Following installation, closely monitor and fine-tune the system for at least 12 months. A BMS can initially perform badly due to poor commissioning. Control loop tuning should be performed to ensure that the equipment operates in a stable, predictable and repeatable manner. Specifications should include a requirement for the BMS contractor to regularly run diagnostic functions, assess energy-use trends, and provide reporting against targeted NABERS ratings.
Other benefits associated with installation of a BMS are outlined below.
Comprehensive control and optimisation
BMS allows comprehensive control and optimisation of equipment cycles, and can be implemented with control algorithms focused on energy efficiency. The following energy saving strategies can be enabled:
- Accurate control of a wider range of comfort conditions, including seasonal temperature adjustments.
- Precise start-up and run times, eliminating excess usage.
- Economy cycle control including CO2 occupancy control.
- Removing all overlap between systems, especially heating and cooling equipment.
- Automatically adjusting for seasonal conditions, including variable plant sequence selection.
- Variable air pressure control and coolant temperature control.
To get the most out of a BMS, correct location and calibration of sensors is crucial. This ensures the BMS is responding to accurate readings at all times. While many modern sensors do not suffer accuracy drift over time, a baseline error of up to one degree can occur and must be offset appropriately. Even greater inaccuracies can occur due to sensors being placed at the wrong height or near heat sources.
Ability to maintain tuning
A BMS helps maintain a building’s optimal HVAC tuning over extended timeframes. It’s common for buildings using stand-alone controls to deviate from their original, optimised settings over time. The US Department of Energy has found that building’s tuning can drift by as much as 30% in the first two years. A BMS can identify and respond to drift in real time, thereby helping to maintain optimum tuning all the time.
BMS can also highlight systemic faults associated with excessive energy use, as well as identification of unusual patterns of energy usage, such as equipment being left on when not needed.
The automated functionality of a BMS takes the pressure off building managers to constantly monitor data and manually intervene in HVAC settings. The time saved on monitoring and tuning can free facilities staff to implement physical improvements and maintenance.
The BMS single-user interface also saves time by bringing all relevant information and controls together in one place. Interfaces can range from basic dashboards through to full graphic workstations, but should always be intuitive to use, making monitoring and analysis easy. A BMS can quickly translate real-time data into useful business information, assisting rapid decision-making.
Lower maintenance costs
A BMS enables early identification of equipment failure. Over time, most buildings become less efficient as operational patterns change and equipment performance declines. A BMS can implement diagnostic functions for most HVAC components, and detect indications that a component is starting to fail. Operators can be alerted via alarms to commence preventative maintenance.
Improved occupant comfort
A BMS allows real-time monitoring and optimisation of occupant comfort, taking into account factors such as temperature, humidity and airflow. A BMS can also improve occupant comfort through air quality management, and by allowing notification and rectification of system faults before comfort is diminished. By supporting high levels of indoor comfort, a BMS helps boost occupant satisfaction, health and productivity outcomes.
Performance management and reporting
A BMS provides performance management and reporting capabilities, helping to ensure energy consumption and star rating targets are met. In high-performing buildings, achieving and maintaining a good NABERS energy rating is crucial to rental income and asset value. A BMS supports performance target management by:
- serving as a diagnostic tool that indicates performance drop in a timely fashion
- providing measurement against load-profile targets and making adjustments as appropriate
- recording historical trend data, including separation into tenant and base building loads
- displaying dashboard-style feedback on energy demand and consumption
Affordable wireless networks
Historically, the expense of implementing a BMS has limited its application to large commercial buildings. However, equipment such as controls and sensors have come down in price, and wireless technology is increasingly commonplace, making BMS installation relatively easy and affordable.
Opportunities to implement a BMS have been enhanced through internet connectivity, with communication between devices or complete systems over a data network replacing traditional hard-wired connections. Recent developments in wireless energy harvesting is enabling a new generation of sensors capable of gaining their required energy from ambient sources.
Grid responsive demand management
The nature of the grid is changing, with increasing need for businesses to tailor their load in response to price signals and potential shortages during severe weather. In addition, building owners are installing more grid-connected generation and storage on their premises.
BMS are increasingly being integrated with software-based, grid-responsive demand management systems or specialised energy management systems (EMS). These software innovations allow for overall optimisation of all energy consumption, generation, export and storage to make best use of energy market conditions at all times.
A BMS can implement strategies to reduce maximum demand charges, which make up a sizeable portion of many business’ energy bills. A BMS can anticipate high building loads and allow appropriate adjustments in advance to avoid maximum demand threshold levels.
Using public weather forecasts, a web-enabled BMS can anticipate favourable or extreme weather conditions and adjust HVAC sequences to achieve the most efficient outcome. For example, if the BMS anticipates a hotter than normal day to come, it can automatically pre-cool the building in advance to take advantage of off-peak energy or more favourable weather conditions.
Integration with broader business systems
A BMS is increasingly being connected to a range of other business systems, allowing a more integrated approach to business management. For example, a BMS can feed into accounting and resource planning systems, or interface with entire facility management systems. The flexibility and cross-compatibility of modern BMS components has removed many barriers between business systems, allowing multiple aspects of a business to be coordinated more effectively.
Integration with building information modelling
Building information modelling (BIM) is a computer 3D modelling process used by architects, engineers, and construction professionals to collaboratively plan, design, construct, and manage buildings.
BMS can be integrated with BIM. This allows a proposed design to be comprehensively simulated and refined prior to construction and, following construction, to compare performance in use with design criteria and design simulations.
BMS - Advanced management and improvement opportunities (PDF 2MB) City of Melbourne
Case study - Using on-bill financing to finance a new building management system (PDF 175KB) NSW Government
A primer on organizational use of energy management and Information Systems (PDF 856KB) US Department of Energy