3.2 Methodology for determining SEUs

There are a number of ways of identifying and quantifying your SEUs.Helpful is worksheet ER3 SUE from EnMS Tool:


If you have sub metering of each or some energy sources then these meters may be able to help or even give a complete picture.

You may also be able to identify gaps in you metering e.g. you may also have sum metering of, say, electricity but not but not fuel or vice versa.

If you don’t have sub metering, which is very common, you may have to estimate by other means – totalling the estimated consumption of different uses. If loads are stable then spot readings with a power meter will allow you to make accurate estimations.

The use of ammeter readings to estimate power is considerably less accurate due to power factor variation.


By totalling all significant consumers you will see what proportion of your total electricity use you are aware of. Typically the principal other use of electricity besides motors is lighting. Some processes use electricity for heating also and if so alternatives should be investigated. Some production processes have no alternative to electrical heating. The same methodology can be used for determining significance of different heat uses.

Key elements to be consider:

  • Find what variable(s) drive their use. Is it production, weather, occupancy, ?
  • Find out which personnel influence these activities and check if they are adequately trained in how to operate and maintain these This activity will feed into the development of training plans for all relevant personnel.
  • Document the critical operating parameters for each The EnMS Tools spreadsheet includes a worksheet (ER6 Critical Op Param) with sample critical operating parameters for different SEUs.
  • Establish baseline energy Establish energy performance indicators for each SEU. Again these should ideally take account of the relevant driving factor(s).
  • Identify opportunities to reduce energy use in each
  • Establish objectives and targets for each
  • If you haven’t identified opportunities to improve the energy performance of any SEU you should carry out a more detailed review of that SEU in order to identify opportuni- ties. This detailed review should review the whole system of that SEU using techniques such as system

Base load energy use is that energy use when there is no activity driving its use i.e. which is independent of any beneficial driver. The causes of high base load are many and varied but might include air compressors left on when no air is being used, lights, PCs, fans, air handling systems, pumps, etc.