Your monitoring and targeting scheme should alert you to any exceptional excess energy consumption by comparing your estimated and actual usage.
You can base your estimate on either:
- the energy you used in previous periods
- the factors that affect the amount of energy you consume
Basing your estimate on previous periods
To base your estimate on your energy use in previous periods you simply compare this month with last month, or this year with last year.
This method is best if your energy use data is seasonal, for example shops that stay open late during the pre-Christmas shopping period.
You may find that this method is too simplistic and that it is more useful to make your estimates by relating energy use to the things that affect it.
Basing your estimate on the factors affecting consumption
You should use this method if there are clear factors that cause your energy use to vary, such as:
- production throughput
- production processes
- the weather
- hours of darkness
Example of Factors affecting energy usage
|Energy use||Possible driving factor|
|Space heating||Outside temperature|
|Air conditioning||Outside temperature - possibly also humidity levels|
|Steam raising||Quantity of steam produced|
|Production process||Production quantity|
Once you know what causes your energy use to vary, you can then begin to estimate your expected usage by measuring the effect each factor has on it.
The Carbon Trust has produced practical guidance on managing energy. This includes details of how to estimate expected consumption. Download guidance on practical energy management from the Carbon Trust website (PDF, 4.8MB).