Building management system or electrical power monitoring system?

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BMS or EPMS? Eaton’s JOHN ATHERTON offers a technical perspective on choosing the right power monitoring system for your facility.

It is well known that optimising power system monitoring and control can go a long way towards enhancing power reliability, efficiency and safety.

Even in today’s energy-conscious world, many building managers do not know where energy is being used or worse, if it is being wasted. Addressing the high cost of energy and need for uptime have become critical to success.

A recent report by the Australian Energy Market Operator (AEMO) predicted a deterioration in Australian power reliability with mass blackouts on the horizon for many homes and businesses this summer. With this in mind, building management teams will need to assess how they can best monitor their energy consumption and understand what solution is right for their facility.

Today, building management teams are increasingly reliant on the combination of two solutions to deliver insight into energy consumption: Building Management Systems (BMS) and Electrical Power Monitoring Systems (EPMS). Energy monitoring is particularly important for data centres, which account for almost four percent of Australia’s total energy consumption and around 10 percent of the world’s energy consumption.

Generally, BMS platforms are used to keep an eye on heating and ventilation systems, as well as lighting, security, fire safety, plumbing and water systems. BMS platforms do not provide the capabilities needed for sophisticated power quality monitoring, however they can be used to detect electrical system issues through basic alarm and control notifications. So, why would you need to build upon these capabilities with an EPMS?

Debunking the myth: BMS v. EPMS

For many building management teams, there are some misconceptions about the functions of EPMS and a BMS.

One of these is that BMS already performs adequate energy monitoring and control.

Yes, BMS systems provide general oversight of safety and lighting management of a building. However, they are not designed to monitor or communicate at the speed that is necessary to analyse electrical events and anomalies. This makes it extremely difficult to regularly capture sensitive power quality data such as harmonic displays or waveform capture. By capturing and communicating electrical system data rapidly, alarm conditions can be propagated immediately and in many cases event correlations can be reconstructed in a forensic analysis.

EPMS systems can also request that each piece of equipment reports once per second. In comparison, one of the most common BMS platforms in the market details that the maximum acceptable response time from any alarm occurrence should not exceed five seconds for network connected user interfaces or 60 seconds for remote or dial-up connected user interfaces. This is a dramatic difference when compared to response times that average under a single second.

Another common misconception is that if a BMS is monitoring parts of the electrical system an EPMS system is unnecessary. It is very common to see a BMS and EPMS monitor the same key points; however, the difference is in what these systems can show. For example, a BMS typically shows what is going on when an issue occurs – for example, where a power outage occurred. An EPMS can also show what is happening, but more importantly, why it has occurred. Understanding the why is far more valuable and necessary in preventing it from reoccurring and has the potential to avoid the situation in the first place.

Informed decision making

Monitoring and managing power distribution systems is critical to successful, energy efficient and reliable operations. An integrated EPMS allows real-time tracking and historical data to identify, monitor and improve wasteful energy practices. System updates are intuitive, making it easy to add or remove devices as electrical systems change so that the EPMS continues to provide an accurate picture of the electrical system over time. Further, an EPMS can integrate third-party products and other critical facility systems (including BMSs, security systems and fire alarm systems). This will help compile complex data in to a unified management platform for informed decision making.

Reliable systems

The critical purpose of an EPMS is to keep systems up and running. In Australia, most data centre operators view having an EPMS as an essential management tool to maximise uptime while minimising operating costs. Data centre operators invest a lot of time and money into ensuring their facility is designed robustly, constructed with high quality components and is intelligently operated. The EPMS system is what provides facility operators, staff and owners with the visibility and assurance that the countless sub-systems are operating as intended.

While many buildings are already measuring energy consumption or keeping an eye on harmonics and voltages, EPMS systems go a step further to provide accurate data on details such as circuit loading, peak demand, equipment status and hundreds of alarms that warn building managers about underperforming equipment and conditions that threaten uptime.

Effective energy monitoring

An EPMS user-defined dashboard gives users complete insight into real-time energy consumption and trended data with intelligent and detailed power quality data on the electrical distribution network extending far beyond the capabilities of a BMS. By providing detailed analysis and reporting on power quality and other important metrics, users can perform detailed analysis to optimise energy use and identify opportunities to reduce electrical power consumption.

An important aspect of any successful energy monitoring program is identification of those facility loads that consume the most energy. An EPMS dashboard will allow users to prioritise energy reduction efforts, including shedding non-critical loads, shifting loads to an off-peak rate period and targeting inefficient operations for further action.

For example, companies/manufacturing plants that want to receive rebate for reducing demand during peak times can use EPMS to verify energy readings, not only lowering energy but also saving money. Selecting a platform for energy monitoring and control or upgrading existing solutions involves justifying the investment and demonstrating a return on that investment. By keeping tabs on energy consumption, companies can usually find ways to realise new savings.

Future planning

Similar to preventing the downtime of today, planning the electrical usage and energy demands of tomorrow can be a difficult job. As site loads increase and usage patterns change, demand on a device may grow beyond its intended capacity. While average demand may not be a concern, peak demand always is, as even a momentary spike has the potential to bring down an entire network.

EPMS products track energy usage over time, immediately inform facility management of peak levels and project future demands based on past usage. This knowledge is critical in planning for electrical upgrades, avoiding unnecessary expenditures and making changes to the power chain to support load patterns.


Electrical consumption and demand should be closely managed to help address other rising costs that are more difficult to control. To this end, the more effective energy monitoring systems in place, the greater impact it will have on overall system reliability and bottom line.

By installing an EPMS to work alongside your BMS, facility management can accurately manage, analyse and trend electrical availability to set the proactive alarms needed to spot problems before they result in costly downtime while easily identifying areas for energy efficiency improvement. The integration can also help with demand response programs, as well as providing accurate consumption levels for calculating power usage effectiveness or utility rebates.

John Atherton is the general manager of power quality, Eaton.


Image: Anthony Indraus,

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