Reporting uncertainty
V2.0 20/09/2016
Contents
Purpose ................................................................................................................................................................ 2
Introduction ..................................................................................................................................................... 2
Background to uncertainty reporting .................................................................................................................. 2
What is uncertainty? ....................................................................................................................................... 2
What is it used for? ......................................................................................................................................... 2
Principles of calculating uncertainty ............................................................................................................... 3
Uncertainty reporting requirements ................................................................................................................... 3
Facilities ........................................................................................................................................................... 3
Facility Aggregates........................................................................................................................................... 4
Incidental and percentage reporting............................................................................................................... 4
Methods for calculating uncertainty ................................................................................................................... 4
Calculating uncertainty: where method 1 is used to estimate emissions....................................................... 4
Calculating uncertainty: where method 2, 3 and 4 are used to estimate emissions ...................................... 4
NGER Uncertainty Calculator 2015-16 ............................................................................................................ 4
Reporting uncertainty in EERS ......................................................................................................................... 5
Calculating uncertainty: Industrial process sources using method 1 .............................................................. 7
Further information ............................................................................................................................................. 8
Abbreviations and definitions ............................................................................................................................. 8
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Purpose
Introduction
Under the National Greenhouse and Energy Reporting Act 2007 (NGER Act), controlling corporations are
required to report on their greenhouse gas emissions, energy consumption and energy production. If certain
requirements are met, corporations reporting under sections 19, 22G or 22X of the NGER Act are also
required to provide a statistical estimate of the level of uncertainty associated with their scope 1 emissions.
Scope 1 emissions are the release of greenhouse gases into the atmosphere as a direct result of an activity,
or series of activities (including ancillary activities) that constitute the facility.
This guide provides information about the reporting requirements for uncertainty under the NGER Act. This
includes information about:

background to reporting uncertainty

reporting requirements for 2015-16 onwards

available methods for uncertainty calculation

how to report uncertainty using the Emissions and Energy Reporting System (EERS)
Background to uncertainty reporting
What is uncertainty?
Uncertainty can be described as the amount of variation in a numerical result consistent with observations.
Statistical uncertainty, as measured under NGER legislation, accounts for the level of uncertainty that may
be attributed to sampling and statistical variation. Uncertainty is to be reported at the 95% confidence level.
An uncertainty assessment of seven per cent, for example, identifies that with 95 per cent confidence the
true value of scope 1 emissions is within seven per cent of the reported value. From basic statistical
principles, the reported figure is more likely to lie near the true value than at the outer limits of the
uncertainty range.
The Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance and Uncertainty
Management in National Greenhouse Inventories contains a broad, all-encompassing definition of
'uncertainty'. This document classifies uncertainty as a general and imprecise term referring to the lack of
certainty in inventory components resulting from any causal factor. For the purposes of reporting under
NGER, uncertainty might be described as a parameter characterising the dispersion of values based on a
statistical analysis of the measurements or emission estimates.
What is it used for?
The uncertainty data provided under NGER legislation will help to inform the uncertainty estimates
published in Australia’s National Greenhouse Accounts, including:

meeting Australia's reporting commitments under the United Nations Framework Convention on Climate
Change (UNFCCC)

tracking progress against Australia’s targets under various international agreements, and

informing policy makers and the public.
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The uncertainty data can also assist corporations in understanding the uncertainties associated with their
emission estimates, informing their allocation of resources and their choice of methods under the NGER
legislation. It is important to note that the submitted uncertainty data is not published annually as part of
section 24 of the NGER Act.
More information on the National Greenhouse Accounts can be found on the Department of Environment
and Energy website.
Principles of calculating uncertainty
There are a number of sources of uncertainty identified in the Uncertainty Protocol1 – however reporters are
only required to estimate the statistical uncertainty. This type of uncertainty results from natural variations.
For example, random human errors in the measurement process and fluctuations in measurement
equipment. More information on statistical and other sources of uncertainty can be found in the Uncertainty
Protocol.
The methods in the Uncertainty Protocol and the National Greenhouse and Energy Reporting (Measurement)
Determination 2008 (NGER Determination) are based on an the assumption that the following principles
hold true for calculating scope 1 emissions:

the estimated parameters are uncorrelated (i.e. all parameters are fully independent)

errors in each parameter are normally distributed

no biases in the estimator function exist (i.e. the estimated value is the mean value), and

individual uncertainties in each parameter are less than 60% of the mean.
Uncertainty reporting requirements
Only uncertainty data relating to section 19, 22G or 22X reportable entities are required to be reported. For
example, if a corporation does not meet the corporate group threshold, but is reporting for a facility that
does meet a facility threshold, only uncertainty relating to the scope 1 emissions from that facility needs to
be included in the final report.
Facilities
Regulations 4.08 and 4.17A of the National Greenhouse and Energy Reporting Regulations 2008 (NGER
Regulations) detail the threshold for uncertainty associated with the estimate of emissions from combustion
of an energy type (i.e. fuel), or from a source, at a facility. Uncertainty must be reported for a facility if the
scope 1 emissions from the combustion of that energy type or for that source are 25,000 t CO2-e or more in
a reporting year. Amendments remove the requirement for uncertainty to be aggregated to the facility and
corporation or group levels.
When reporting under regulation 4.28, a Network/Pipeline is treated as though it is a simple 'facility' and is
therefore subject to uncertainty reporting requirements.
1
GHG Protocol guidance on uncertainty assessment in GHG inventories and calculating statistical parameter
uncertainty (September 2003 v1.0)
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Facility Aggregates
Facilities must not be reported within a facility aggregate if scope 1 emissions from the facility are 25,000 t
CO2 -e or more (see NGER Regulation 4.25). Therefore, emissions from facility aggregates are not subject to
uncertainty reporting requirements.
Incidental and percentage reporting
Data reported as an incidental under Regulation 4.27 is not subject to uncertainty reporting requirements.
Data reported as a percentage under Regulation 4.26 is not subject to uncertainty reporting requirements.
Methods for calculating uncertainty
The NGER Determination provides up to four methods for determining scope 1 emissions. Part 8.1 of the
NGER Determination provides that uncertainty must be assessed according to the method by which
emissions for the source were estimated.
Calculating uncertainty: where method 1 is used to estimate emissions
Part 8.3 of the NGER Determination provides default uncertainty values which can be used to calculate the
uncertainty for emissions estimated using method 1. Default values in the NGER Determination are either
aggregated uncertainties or uncertainties for parameters needed to calculate the emissions. For fuel
combustion, these vary due to the variable range of compositions of each fuel type. Liquid fossil fuels
generally have a limited range of compositions, and therefore have a low associated uncertainty. Biofuels
have an apparently high default uncertainty, as they are generally heterogeneous in composition.
In some situations, reporters have the option of performing their own assessment of uncertainty in
accordance with the Uncertainty Protocol (refer to part 8.3 of the NGER Determination).
Calculating uncertainty: where method 2, 3 and 4 are used to estimate
emissions
As set out in part 8.4 of the NGER Determination, calculations of uncertainty of scope 1 emissions estimated
by methods 2, 3 or 4 are to be made in accordance with the Uncertainty Protocol. Item 4, Part 7 of the
Uncertainty Protocol is not to be used when emissions are estimated using methods 2, 3, or 4.
NGER Uncertainty Calculator 2015-16
The Clean Energy Regulator has provided a spreadsheet tool that can help reporters calculate uncertainty.
For a step by step guide on how to use the Uncertainty Calculator and related EERS functions, refer to the
NGER Uncertainty Calculator User Guide.
The Uncertainty Calculator and its user guide are both available for download on the Clean Energy
Regulator’s website.
Note that it is not compulsory to use the Uncertainty Calculator. Reporters may use their own method, in
line with the NGER Determination.
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Reporting uncertainty in EERS
In order to report uncertainty, reporters must ensure all relevant activity data has been entered into EERS.
To report uncertainty, click on the 'Data Entry' tab and then on the 'Report Uncertainty' button, found on
the lower left, underneath the Favourites pane (Figure 1).
Figure 1: Report Uncertainty button on the lower left
The Facility Uncertainty reporting screen (see Figure 2) shows all sources and fuels that exceed the
uncertainty reporting threshold for the organisation.
For the 2015-16 reporting year, the Facility Uncertainty reporting screen will include an ‘Auto-calculate’
option, which when clicked calculates uncertainty using default values for the fuel type or source where
Method 1 has been used to estimate scope 1 emissions. Reporters can choose which method 1 fuel or
source items they want to exclude from auto-calculation by unticking the checkbox in the 'Auto-calculate'
column (see Figure 2). Note that an auto-calculate checkbox will only be available where only Method 1 was
used to estimate emissions for the fuel and source item.
To return to the Reporting Entity Information screen, click the 'Exit' button.
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Figure 2: Uncertainty screen with Auto-calculate button on top right and Auto-calculate checkboxes
To enter, modify or remove any reported uncertainty value, click the edit symbol in the 'User input' column.
This will open the uncertainty add/modify entry screen (shown in Figure 3).
On this screen, reporters should enter the uncertainty related to the activity data for the fuel or source in
the 'Uncertainty Percentage' field on the left hand side of the screen ). Reporters may choose to use the
Uncertainty Calculator to calculate and report uncertainty in accordance with the NGER Determination.
Figure 3: Add/modify – Uncertainty entry screen
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NOTE: It is important to remember to perform uncertainty reporting last, because if any activities relevant
to uncertainty reporting are adjusted, uncertainty will need to be re-entered.
Calculating uncertainty: Industrial process sources using method 1
The table below (Table 1) specifies industrial process sources that do not have default uncertainty values in
the NGER Determination. If emissions from these sources involve the combustion of a fuel, then default fuel
combustion uncertainty factors may be used for emissions attributable to each fuel. Otherwise, the autocalculate uncertainty function will use a default uncertainty value of 10% for the source in accordance with
the ‘worksheet’ of the Uncertainty Protocol.
Table 1: Sources without default uncertainty values in the NGER Determination
Source
Sodium cyanide production
Soda ash production
Ammonia production
Carbide production
Chemical or mineral production (other than carbide production) using a carbon reductant or carbon
anode
Iron, steel or other metal production using an integrated metalworks
Ferroalloys production
Aluminium production (where activity is emissions from the production of baked carbon anodes)
Other metals production
Calculating uncertainty from Methods 2, 3 and 1 (non-default factors) emissions
Uncertainty for emissions estimates calculated under Methods 2, and 3 must be calculated in accordance
with the Uncertainty Protocol (Part 8.4 of the NGER Determination). Under certain circumstances, outlined
in part 8.3 of the NGER Determination, uncertainty for emissions estimated under Method 1 can also be
calculated in this manner. Refer to the Uncertainty Calculator user guide for how to apply these methods in
the Uncertainty Calculator.
Calculating uncertainty from Method 4 emissions estimates
Assessments of uncertainty for emissions estimated under Method 4 must conform to principles outlined in
the Uncertainty Protocol. Refer to the Uncertainty Calculator user guide for how to apply these methods in
the Uncertainty Calculator
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Further information
Email: [email protected]
Phone: 1300 553 542
This fact sheet is not a substitute for independent professional advice. Controlling corporations are
responsible for applying the legislation to their particular circumstances and organisational structure.
Abbreviations and definitions
Term
Definition
EERS
Emissions and Energy Reporting System
NGER
National Greenhouse and Energy Reporting
NGER Act
National Greenhouse and Energy Reporting Act 2007
NGER Determination
National Greenhouse and Energy Reporting (Measurement)
Determination 2008
NGER Regulations
National Greenhouse and Energy Reporting Regulations
2008
t CO2-e
Tonnes of equivalent carbon dioxide
the Uncertainty Calculator
NGER Uncertainty Calculator 2015-16
Uncertainty Protocol
GHG Protocol guidance on uncertainty assessment in GHG
inventories and calculating statistical parameter uncertainty
(September 2003 v1.0)
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1300 553 542
[email protected]
www.cleanenergyregulator.gov.au
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