Energy Management Systems (EnMS): Meaning & Benefits

Mar 18, 2024 | News | 0 comments

What is an Energy Management System?

Organisations are under pressure to improve sustainability, and one practical way is to reduce their energy use, which in turn reduces the carbon footprint.  An energy audit can point the way to achieving this. However, this is usually a once-off exercise and without a systematic approach to monitoring energy use after the audit, it’s easy for the carbon footprint to slowly increase.  Therefore, a system to manage energy is required; such a system is termed an energy management system.

An energy management system (EnMS) is not a bolt-on system to measure energy use at a fine level and provide an array of statistics such as kWh/widget, but a systematic approach to identifying the causes of variation in energy use and eliminating them. The system will also include policies for staff training and purchasing.  The actual analysis tools need to be similar to Six Sigma techniques. 


Implementing an Energy Management System

Energy Audit

The first step in implementing an energy management system is to have an energy audit.  The audit will start off by collecting a minimum of 12 months of energy use data.  Data for the level of activity is also required. For an office, this may be employees present per month.  For a manufacturing plant, this could be items manufactured per month. The auditor will then undertake some initial analysis to uncover trends in energy use such as space heating energy use normalised by weather for an office or kWh/widget for a manufacturing plant.  This will give the auditor a focus.  For example, if the relationship between space heating energy consumption and outside weather (degree days) is not near linear, the auditor will look more closely at the heating controls.

The audit will identify a number of energy-saving opportunities.  Importantly, the audit will also identify the significant energy users in the organisation and how well-controlled the energy use is for these significant users.  This will then guide how the energy management system is to be implemented.  The energy management system will need to monitor the energy consumption of the significant users, and some form of sub-metering will be needed for this.  For example, if gas is used both for space heating and for some processes (e.g., heating treatment tanks), then the gas for the space heating should be submetered to give daily readings.

Utilising Good Quality Data

The ability to collect good quality and timely data is essential and the audit will have identified what needs to be metered.  The data then needs to be analysed on a regular basis.  For small organisations, this can be carried out manually using spreadsheets monthly.  At the other end of the scale, such as a large pharma plant, the data should be collected automatically and analysed on an hourly or daily basis.  The analysis can be automated with exception reports generated.  For example, if the kWh/litre increases outside of an acceptable range, then warnings are generated.  There are many commercially available systems to undertake this.


What are the Benefits of an EnMS?

There are significant benefits in having an organisation-wide EnMS

  • By understanding the causes of variations in energy use, opportunities to reduce energy use can be evaluated, implemented and the success or otherwise determined.
  • Enables better communication with staff and stakeholders in move to improved sustainability
  • Allows evaluation of alternative energy supply strategies
  • Provides clear and consistent information for CapEx decisions

Many surveys have confirmed the energy-saving benefits of such systems.  A UK Department of Energy Survey found that the average annual savings identified by companies implementing such systems was 13%, and in some cases, savings of more than 25% were obtained.  


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This article has focused on the collection and analysis of data.  There are other aspects to energy management such as training and purchase policies. ISO 50001 is the standard for energy management and should be used as a basis for documenting your system.

The author of this article, Bob Sutcliffe, is a Chartered Engineer and Certified Energy Manager.  Bob is listed on the Irish SEAI and UK ESOS registered of approved energy auditors.