The Metered Baseline Method compares electricity consumption before and after the energy savings project (or 'Recognised Energy Savings Activity' as defined in the legislation) is implemented. The difference in consumption is used to calculate the energy savings delivered by the energy savings project.
The Metered Baseline Method relies on the remainder of the site operating as it did before the energy savings project was implemented.
Determining the baseline
A number of different sub-methods are provided in the ESS Rule to determine the baseline before the energy savings project and the calculation of energy savings certificates:
- Baseline per Unit of Output
- Baseline Unaffected by Output
- Normalised Baseline, or
- National Australian Built Environment Rating System (NABERS) baseline.
For more detailed information please refer to the Energy Savings Scheme Rule and the Application Guide.
Baseline per Unit of Output
This method is most appropriate where consumption is strongly linked to output (eg, aluminium smelting).
You may use this method if:
- the consumption of all energy sources for the site are linear functions of output (that is they directly reflect each other)
- the energy consumption is fixed (that is, the proportion of energy consumed at the Site does not vary with variations in output) and can be measured or estimated, or
- output has not changed by more than 50% from the average output over the period that the variable baseline was measured.
Baseline Unaffected by Output
This method is most appropriate where consumption is not linked to output (eg, schools and swimming pools).
This method is most appropriate where the baseline needs to be normalised to remove explainable variation from the baseline. Examples may include changes to ambient conditions or input characteristics.
Option C of the International Performance Measurement and Verification Protocol (IPMVP), published by the Efficiency Valuation Organization (EVO), can be used for guidance for normalising baselines. A copy of the 2012 IPMVP can be obtained via this link: http://www.evo-world.org/index.php?option=com_form&form_id=75&Itemid=535.
The National Australian Built Environment Rating System (NABERS) method is based on the Normalised Baseline approach and consists of 2 methods - Method 4a and Method 4b in the Energy Savings Scheme Rule.
Method 4a is for existing NABERS buildings and Method 4b for new NABERS buildings. These methods are to be used for normalising baselines of offices, hotels and shopping centre buildings that use the NABERS for measuring building energy performance