Metered baseline method

Written and checked by the Energy Merchants desk · Reviewed 3 October 2026

The metered baseline method uses a site’s own meter data to prove an energy saving. It is one of the calculation methods under the NSW Energy Savings Scheme (ESS). Instead of a table value, the saving comes from comparing real consumption before and after the upgrade.

The steps

1. Collect baseline data. Metered consumption, often a year or more of it, for the equipment or the whole site, along with the drivers that affect it, such as production output or operating hours.
2. Build the baseline model. The relationship between those drivers and energy use becomes the expected consumption without any upgrade. See ESS baseline.
3. Install the upgrade.
4. Measure after. Consumption is metered again over a reporting period.
5. Calculate the saving. The difference between the baseline model’s prediction and the measured use, for the same conditions, is the energy saving. ESCs follow from it.

A worked figure

Suppose the baseline model predicts 600 MWh over a period, given production levels, and the site meters 540 MWh after the upgrade. The saving is 60 MWh. The ESC count then follows from the scheme’s conversion rules, which a certificate provider applies. Do not estimate it from this page.

In practice

The method suits sites with good sub-metering and stable operations, like a plant with a clearly metered process line. It is weaker where use is erratic or the data is poor, because the baseline model will be uncertain. A project that spans a whole building may fit project impact assessment better. Where the upgrade is a standard product, deemed savings are simpler.

An accredited certificate provider (ACP) must hold the data and register the certificates. See accredited certificate provider.

Common confusion

It is not the same as a simple before-and-after bill comparison. Without adjusting for production and weather, a quiet month will look like savings. Nor is it a rooftop solar method. STCs for solar use deemed output and no metering.

For the broader picture see certificate trading glossary and the glossary, and how it works.