Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

GEN ERA L BACKGROUND PAPER
ACKNOWLEDGEMENTS
This paper was written by Dina Kruger (USEPA) and reviewed by Ian Galbally (CSIRO), William Irving(USEPA), Thomas Martinsen (IPCC/OECD/IEA Inventories Programme), and Jim Penman (DETR, UK).

General Background Paper

1Background Paper

1

OVERVIEW OF THE WORKSHOPS SCOPE
AND GOALSIn June 1998, the Subsidiary Body on Scientific and Technological Advice (SBSTA) asked IPCC to “...give highpriority to completing its work on uncertainty, as well as to prepare a report on good practice in inventory
management (emphasis added) and to submit a report on these issues for consideration by the SBSTA, if
possible by COP 5.” The IPCC developed its work-plan for preparing this report at an expert meeting held inParis in October 1998.
The current state of practice in national greenhouse gas inventories is reflected in the Revised 1996 IPCC
Guidelines for National Greenhouse Gas Inventories (IPCC Guidelines). The use of the IPCC Guidelines was
agreed at Kyoto. These IPCC Guidelines contain a detailed list of source categories, but they are less prescriptive
about calculation methods. In fact, the IPCC Guidelines encourage Parties to use their national methods andassumptions where these are more accurate than the methods described in the Guidelines. At the Paris expert
meeting, it was agreed that the use of good practice procedures in the selection of emission factors,
methodologies, and activity data could reduce uncertainties and minimise the possibility of bias in emission
inventories. In this case, the values recorded (although uncertain) would be the best available estimates of actual
emissions, and therefore presumably the best available basis for assessing compliance with commitments under
the Convention and the Protocol. Good practice can refer not only to estimation methods, but also to the way inwhich inventories are managed, including the management of uncertainty. The idea of good practice was also
extended to ensuring transparency for review purposes, to quantify uncertainties and to cross-checking national
estimates with independent calculations and empirical data.
Good practice guidance developed to supplement the IPCC Guidelines could be considered by the Parties forincorporation into the guidelines for national inventory systems to be decided under the provisions of Article 5 of
the Protocol or as supplementary information under Article 7. How prescriptive the good practice guidelines
should be will of course be for the Parties to decide; the role of the IPCC is to provide necessary technicalinformation on what is feasible. This could include the selection and application of estimation methods andmanagement of inventories in terms of quality control and review procedures to ensure unbiased estimates.
In order to define good practice within the context of the IPCC Guidelines, the Paris meeting proposed that the
IPCC should organise four sectoral workshops dealing with good practice in inventory estimates. A fifth
workshop will deal with cross cutting issues on quality assurance/quality control (QA/QC) and the quantificationand management of uncertainties, and a concluding workshop to ensure consistency in the definition of goodpractice as a whole. These workshops would be held in 1999 and 2000 and be scheduled so that a substantive
report on progress could be made available, bearing in mind the timetable suggested by SBSTA.
The sectoral workshops will focus on developing good practice guidance that will promote the development ofemission inventories that contain unbiased, reliable and accessible data that can be readily assessed in terms of
quality and completeness, and can be reasonably achieved considering the resource considerations of all
applicable Parties. In essence, the fundamental question for consideration at the sector workshops is: How do we
define good practice for a particular emission source category? Based on discussion at the Paris meeting, thefollowing issues will be considered at the sector workshops at the source level:•

Identification of preferred emission estimation methods, including selection and use of emission; factors andactivity data, completeness, and uncertainty;•

Considerations for transparency and reporting, and•Considerations for quality assurance (QA) and quality control (QC).

The good practice guidance should outline a high standard for inventory quality within the context of the IPCC
Guidelines that will give confidence in the use of inventories for assessing compliance. The good practiceguidance should recognise the diverse national conditions of data availability, resource constraints, andinfrastructure, and should recognise that inventories will improve over time.
Table 1 summarises these issues and the following sections discuss them in more detail. The sector workshops
will develop recommendations on these specific components of good practice guidance as they relate to eachsource category. A model of the areas to be addressed in the good practice guidance is attached as Annex B tothis paper. It is anticipated that the results of each expert group’s work will be approximately 5 pages long andfollow this format.
To assist expert groups in their work, technical papers are being prepared for each source category, outlining how
these issues may apply to the source. These technical papers will form the basis of discussion at the sector workshops.

2

Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

TABLE 1EXPECTED OUTPUTS FROM SECTORAL WORKSHOPS
Inventory Attribute
Methodological Issues

Outputi.

Identification of good practice for methodological choices for estimating
emissions, including development of a decision tree for determining what
method is most appropriate, given national circumstances.

ii.

Guidance on the use and/or development of emission factors and associateduncertainty rangesiii. Guidance on the use and/or development of activity data and associateduncertainty ranges
iv. Information on uncertainty for the upcoming meeting (in October 1999 in
the United Kingdom)v.

Guidance on completeness of emission estimates in the source category

vi. Guidance on other important issues, such as consistency in time series, etc.
Reporting andDocumentationi.

Clear definitions of the end uses of data and corresponding implications
on reporting and documentationii.

Minimum elements for transparency and reproducibility on a source categorybasis using IPCC reporting tables, taking UNFCCC Guidelines into accountiii. Existing tools, or recommended new approaches, to collecting and storing
emissions-related data to facilitate comparisons, transfer, and review ofinventory data
Inventory Quality
Assurance and Quality
Control

2i.

Guidance on which QA/QC tools best represent good practice in inventory
management for particular sourcesii.

Recommendations on how to document good practice in QA/QC procedures

METHODOLOGICAL ISSUES

The selection and application of emission estimation methods are fundamental to inventory quality. Under the
IPCC Guidelines, Parties have a great degree of flexibility in their selection of emission estimation methods. A
variety of approaches or “tiers” are outlined in the IPCC Guidelines, ranging from simple default methods tomuch more complex approaches. Complete standardisation in methodologies is neither likely nor desirable,
given differences among Parties. Thus, good practice guidance provides an alternative means of ensuring thatthe method employed is used appropriately. To this end, good practice guidance on emission estimation methods
should address the following:•

Which method is chosen;•

How emission factors are developed and used;•

How activity factors are developed and used;•

Uncertainty associated with various methods;•

Completeness, and•Other Important Issues.

2.1

Choice of method

The main goal of the sector workshops will be to review the emission methodologies described in the IPCC
Guidelines and develop good practice guidance on how to select and apply the most rigorous method appropriate
for each source, taking into consideration available national circumstances and resources.
Good practice methods should yield a high quality unbiased emissions estimate. They should be challenging yet
allow for Parties' varying capabilities in terms of resources. Good practice should take account of all methods
consistent with the IPCC Guidelines, up to and including direct monitoring of emissions where feasible. A good

General Background Paper

3

Background Paper

practice method employing the “emissions factor X activity data” or other appropriate algorithm should bedisaggregated spatially and by sub-source to the furthest extent possible, and take into consideration the uniquecharacteristics of the country. Disaggregation allows for the algorithm to be applied to increasingly homogenous
data sets. One or more good practice methods should be identified for all sources, together with a decision tree
or equivalent to guide Parties to the method most appropriate to their circumstances. Decision trees should
recognise that any Party may choose to use most detailed methods consistent with the IPCC Guidelines and theassociated reporting requirements. The relative size and/or rate of change of a source in a national inventory may
play a role in determining good practice, but an evaluation of whether a particular source is “key” is not an issue
that will be addressed by expert groups at the sector workshops.
In source breakout groups at the sector workshops, experts should identify good practice methods for estimating
emissions from their source. They should also develop a decision tree that describes the process by which a Party
would determine which method or tier was most appropriate given its national circumstances. Annex B includes
a sample decision tree which should be adapted for each source. Guidance has also been developed on howgroups are to work within the IPCC Guidelines as they consider the issue of methodological choice (see Box 1).
BOX 1
DRAFT CRITERIA FOR GOOD PRACTICE BEING CONSISTENT WITH IPCC GUIDELINES

Applying good practice guidance should reduce uncertainties and minimise the bias in greenhousegas inventories produced through the use of the IPCC Guidelines. The breakout groups should use
the following criteria to decide whether the good practice guidance that they are proposing is
consistent with the IPCC Guidelines:(a)Good practice guidance should address the same source categories and gases as the IPCC
Guidelines;(b)

Good practice guidance should use the same functional forms for the equations used toestimate emissions that are used in the IPCC Guidelines;(c)

New default emission factors can be suggested where high quality data are available that are
more up-to-date or appropriate for use in particular circumstances that can be identified
through the decision tree. Such new factors should give more accurate estimates than thecurrent factors and must be documented;(d)Good practice guidance should identify any errors that there may be in IPCC Guidelines, and(e)

Where relevant, groups can identify and describe good practice for additional sources,
source categories, or gases (i.e., those included in the Other category).

Breakout groups should provide guidance on the choice of method (by decision trees), theselection of parameter values which are linked to particular circumstances, situations in which
national methods are appropriate, and propose corrections for any errors.

2.2

Choice of emission factor

The quality of emission factor or other model parameter1 data is critical to the quality of the resultant emission
estimates. Thus, availability, applicability, and quality of the emission factor data needed for each method must
be assessed. For each source, experts will need to identify the types of emission factor data required to
implement the different methods. Once the necessary emission factors are determined, experts should evaluate
how they should be obtained and identify any areas of concern with the development of new emission factors.
Key considerations for using national emission factors or IPCC default factors should also be identified.
Several Parties develop their emission estimates using national emission factors derived from measurement
programmes undertaken in their own countries or regions. These emission factors are generally more appropriate
than IPCC default factors, because they specifically address national circumstances. Where national or regionalemission factors are used, experts should develop guidance for selecting or developing emission factor data for agiven estimation approach. Experts should specify the key elements of a high-quality emissions measurement
programme for particular sources and/or methods. In addition, they should identify the documentation necessary
for reviewers to assess the quality of emission factors. Such documentation might include a description of the

1 Such as the parameters of a process model which play an equivalent role to emission factors. Emission factors

referred to here include these parameters

4Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

measurement programme, references to technical literature, and /or a discussion of why national emission factors
differ from IPCC defaults.
Many Parties, particularly those with limited financial and/or personnel resources, use default emission factors
identified in the IPCC Guidelines in developing their inventories. To ensure highest quality, the default emission
factors presented in the IPCC Guidelines should be reviewed and updated where possible, consistent with theguidance in Box 1.
In certain cases, it may be good practice to “borrow” emissions factors from another country which hascompleted a domestic measuring programme and developed its own data. In these cases, the country should have
similar economic and physical circumstances, as they apply to the source in question. Experts should also
consider whether the good practice guidance should contain an updated registry of emission factors for various
sources. A registry listing the values and pedigree of a range of emissions factors could make it easier forcountries to choose the most suitable data. The development of such a registry would be a central function for
the IPCC or possibly for the UNFCCC Secretariat.
The review of emission factors at the sector workshops may also identify areas for substantial improvement inemission factor data. For some sources, there may not be a readily available set of emission factors withacceptable quality and applicability to apply the preferred estimation method. This scenario could lead to a
recommendation for further research into the literature or for Parties undertaking the development of improved
emission factor data from measurement programmes within their country.
At the sector workshops, expert groups should determine what emission factors are needed for each tier or
method, and describe good practice in obtaining these default factors. The applicability of default factors in the
IPCC Guidelines should be reviewed and good practice guidance provided as necessary. Uncertainty issues
related to emission factors should be addressed (see discussion in Section 2.4). If new data are available toenable improvement in default emission factors, they can be discussed and documented.

2.3

Choice of activity data

The accuracy and reliability of activity statistics varies widely. Fuel consumption data are usually reliable inmost Annex I countries, but problems can arise; for example, the division between domestic aviation andinternational aviation bunker fuels (the emissions from which are not currently included in national totals) is
usually not well defined. For some other sectors the activity statistics may be of much poorer quality. Examplesof these are: waste statistics may not be collected or may be incomplete, and statistics on some agricultural
treatments are not collected.
The first step is to determine the type of activity statistics required for the various estimation methods. It is
crucial that the activity data match the level of aggregation of emissions factors as called for by themethodology. For example, a disaggregated method for estimating methane emissions from livestock requiresthat dependable livestock population data be available to match the emission factors. Otherwise, there will be a
specification error in the estimate. There may be a point at which the gains to disaggregation are outweighed by
the scarcity of activity data at that level.
Once the necessary activity data are specified, the next step is to evaluate how to obtain the data and identify any
areas of concern. As is the case with emission factor data, there may be a variety of reference sources andformats for the activity statistics that can be used to support a particular method. For some emissions sources, itwill be possible to collect activity data annually solely for the purpose of constructing an emissions estimate. In
the absence of customised data collection, however, pre-existing data collected for other purposes by othergovernment agencies or independent organisations will be necessary. This has the benefit of conserving scarce
resources, but there are issues to be aware of. Depending on the transparency of the data, it may be difficult toascertain its quality or bias. Some data sets (such as livestock populations) may not be collected annually, so it isnecessary to interpolate or scale to other annual data. More often, the data may be published in one format, andhas to be transformed into another before it is applied to the estimation of emissions. If there are two competing
data sets with different results, they will have to be reconciled.
At the sector workshops, expert groups should determine the types of activity data required for each tier or
method and describe how they should be obtained. Uncertainty issues related to activity data should be addressed(see Section 2.4).

2.4

Uncertainty assessment

At the October 1998 expert meeting, it was decided that the current IPCC Guidelines on uncertainty assessment
should be expanded to provide more detailed guidance to Parties on how to assess and communicate theGeneral Background Paper

5

Background Paper

uncertainty in their emissions inventories. Much work remains to be done to identify the most appropriate
methods for assessing inventory uncertainty, however, and a separate workshop addressing the approaches for
estimating and reporting uncertainty will be held in October 1999. In preparation for that meeting, expert groups
at sector workshops are requested to consider the issues presented in Box 2.
BOX 2
REQUEST TO BREAKOUT GROUPS CONCERNING UNCERTAINTIES (BY IAN GALBALLY, AUS)

The Expert Meeting on Uncertainties (UK October, 1999) will require input from experts from the
Sector Workshops to aid its overarching discussions on design of a good practice system for
uncertainties. As part of your breakout group discussion and report to the Sector Workshop you
have been given a “framework for Breakout Group Two Page Summaries”. The document
indicates in three places where you need to provide information on uncertainties. These notes are
to clarify those tasks as follows:
Section: Choice of emission factor
The first requirement for uncertainties in the Framework document is for “Default emission factors
and associated uncertainty ranges”. These uncertainty ranges that we are soliciting are default
uncertainty estimates. As part of your report please provide a list of default quantitative
uncertainty ranges (expressed as a +/-percentage of the mean value) for emission factor, along withthe default emission factors for each component of the IPCC Inventory that your breakout groupconsiders. These uncertainty ranges are 95 percent confidence limits on the annual values enteredinto the IPCC Inventory worksheets. Please specify for each uncertainty whether it is based on
numerical data (by providing a reference) or expert judgement (with a note of the source). The
default uncertainty is the reasonable estimate of uncertainty to be applied to an activity, emission
factor or emission rate for the national inventory of a Party to the Convention where no local
information (in that nation or Party) on the uncertainty exists.
Section: Choice of activity data
The second requirement for uncertainties in the Framework document is the uncertainty associatedwit activity data. These uncertainty ranges that we are soliciting are default uncertainty estimates.
As part of your report please provide a list of default quantitative uncertainty ranges (expressed as
a +/- percentage of the mean value) for activity data for each component of the IPCC inventory
that your breakout group considers. These uncertainty ranges are 95 percent confidence limits on
the annual values entered into the IPCC Inventory worksheets. Please specify for each uncertainty
whether it is based on numerical data by providing a reference) or expert judgement (with a note of
the source).
Section: Input to Uncertainty Workshop
Are there any examples covered in your considerations where there are multiple determinations on
a particular system of either the emissions, emission factors or activities that would be adequate tocharacterise the variability of the system and determine a probability distribution of the parameter.
Please provide an explicit reference or contact person for the source of the data.
Are there any examples where there is likely to be correlation between the activity and emission
data, or correlation between two activities used in the same emissions estimation equation. Can
these correlations be quantified? Please provide an explicit reference or contact person for thesource of the data.
Are there any national conditions where the methodology for emissions estimation is inappropriate
or fails because the methodology was not designed to present those conditions? Please indicate any
possible cases and proposed reasons for those breakdowns.

2.5

CompletenessFor many sources, ensuring completeness is straightforward. For others, however, it may be difficult for Parties
to develop emission estimates for numerous sub-sources and difficult for inventory reviewers to determine howcomplete the estimates are. Thus, good practice guidance should address the following issues for each source
category:•

Clear definitions of what is included in a particular IPCC source category (i.e., the sub-sources), and•Whether completeness is likely to be an issue for a particular source. If necessary, the guidance should
describe those sub-sources that may merit particular attention to ensure completeness. They should also6

Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

indicate whether the terms NA, NE, or NO are likely to be used for this source and if there are any special
considerations on how these terms are applied (see Box 3 for the UNFCCC definitions ).
BOX 3
UNFCCC DEFINITIONS REGARDING COMPLETENESS

Where methodological or data gaps in inventories exist, information on these gaps should bepresented in a transparent manner. Parties should clearly indicate the sources and sinks notconsidered in their inventories but included in the IPCC Guidelines, and explain the reason for the
exclusion. In addition, Parties should use the standard indicators presented below to fill the blanks
in all the tables of an inventory. This approach facilitates assessment of the completeness of an
inventory. The standard indicators are as follows:

2.6

(a)

"NO" (not occurring) for emissions by sources and removals by sinks of greenhouse gasesthat do not occur for a particular gas or source/sink category within a country;(b)"NE" (not estimated) for existing emissions by sources and removals by sinks of greenhousegases which have not been estimated. Where "NE" is used in an inventory for emissions or
removals of CO2, N2O, CH4, HFCs, PFCs, or SF6, the Party should indicate, using thecompleteness table of the common reporting format, why emissions could not be estimated;(c)"NA" (not applicable) for activities in a given source/sink category that do not result inemissions or removals of a specific gas. If categories in the common reporting format for
which "NA" is applicable are shaded, they do not need to be filled in;(d)"IE" (included elsewhere) for emissions by sources and removals by sinks of greenhousegases estimated but included elsewhere in the inventory instead of the expected source/sink
category. Where "IE" is used in an inventory, the Party should indicate, using thecompleteness table of the common reporting format, where in the inventory the emissions or
removals from the displaced source/sink category have been included and the Party should
give the reasons for this inclusion deviating from the expected category;(e)"C" (confidential) for emissions by sources and removals by sinks of greenhouse gases
which could lead to the disclosure of confidential information, given the provisions ofparagraph 19 above, and(f)"0" for emissions by sources and removals by sinks of greenhouse gases which are estimatedto be less than one half the unit being used to record the inventory table, and which therefore
appear as zero after rounding. The amount should still be included in the national totals andany relevant subtotals. In the sectoral background tables of the common reporting format
Parties should provide data as detailed as methods allow.

Other issues

In addition to issues of completeness and uncertainty, several other important methodological issues may need tobe considered with respect to certain sources. Possible issues for consideration include:•

Establishing base year emission levels – for some sources, it may be necessary to consider the mostappropriate means of developing a base year estimate, given the possibility that estimation methods or data
sources used in later years may differ from the base year. This issue may be particularly important forsources where measured data were unavailable in the base year, but such data are available for developing
more accurate estimates in later years;•

Treatment of imported/exported emission sources – the issue of how to treat an emission source that is
imported or exported may arise for some sources (an example is the chemicals that replace ozone-depleting
substances). Experts may want to consider where such emissions should be accounted for and/or how
estimates should be reported to ensure transparency in the coverage of these sources;•

Consistency among sources – some sources may use similar sets of activity data in preparing estimates.
These linkages should be identified, to ensure that the data sets are manipulated in a consistent manner
across the sources;•

Double counting – experts should consider the interactions among sources to ensure that emissions are notdouble counted, andGeneral Background Paper

7

Background Paper•

3

Confidentiality – experts should determine whether confidentiality is a potential concern with respect to thedata used in developing the estimates. If so, they should make recommendations about how maximum
transparency can be achieved while protecting confidentiality.

REPORTING AND DOCUMENTATION

Reporting of national greenhouse gas inventories allows Parties to evaluate their progress towards meeting thegoals outlined in the UNFCCC, and will be used by developed countries to determine compliance with binding
emissions targets outlined in the Kyoto Protocol. Without sufficient reporting, it will be impossible for third
parties to judge whether or not national inventories reflect a rigorous attempt to estimate the true annual
emissions within a country. In short, without good practice in reporting, it is impossible to assess inventory
quality. In fact, poor reporting may lead reviewers to conclude that the inventory is highly uncertain, or possibly
suspect, even if the data are of high quality. From a global inventory perspective, poor reporting makes it difficult
to compare inventories across countries, and to compare global atmospheric budgets with inventory estimates.
Sufficient reporting means that inventories can meet the standards of the Parties to the Convention and theProtocol. The UNFCCC, in its “Guidelines for the Preparation of National Communications by Parties Includedin Annex I to the Convention, Part I: UNFCCC Reporting Guidelines on Annual Inventories”(FCCC/CP/1999/7), outlined guidelines for reporting national inventories. Decision 10/CP.2 of the same
document outlines guidelines for non-Annex I Parties. In this document, the standards for reporting anddocumentation are defined as follows (see Box 4):
BOX 4
UNFCCC REPORTING GUIDELINES PRINCIPLES AND DEFINITIONSTransparency means that the assumptions and methodologies used for an inventory should beclearly explained to facilitate replication and assessment of the inventory by users of the reported
information. The transparency of inventories is fundamental to the success of the process for thecommunication and consideration of information;
Consistency means that an inventory should be internally consistent in all its elements withinventories of other years. An inventory is consistent if the same methodologies are used for thebase and all subsequent years and if consistent data sets are used to estimate emissions or removals
from sources or sinks. Under certain circumstances, an inventory using different methodologies fordifferent years can be considered to be consistent if it has been recalculated in a transparent
manner, taking into account any good practices;
Comparability means that estimates of emissions and removals reported by Parties in inventories
should be comparable among Parties. For this purpose, Parties should use the methodologies andformats agreed by the COP for estimating and reporting inventories. The allocation of different
source/sink categories should follow the split of the IPCC Guidelines, at the level of its summaryand sectoral tables.
Completeness means that an inventory covers all sources and sinks, as well as all gases, includedin the IPCC Guidelines, as well as other existing relevant source/sink categories which are specificto individual Parties, and therefore may not be included in the IPCC Guidelines. Completenessalso means full geographic coverage of sources and sinks of a Party.
Accuracy is a relative measure of the exactness of an emission or removal estimate. Estimatesshould be accurate in the sense that they are systematically neither over or under true emissions or
removals, as far as can be judged, and that uncertainties are reduced as far as practicable.
Appropriate methodologies conforming to guidance on good practices should be used to promoteaccuracy in inventories.
The UNFCCC Guidelines also prescribe the use of standard data tables and formats for reporting as
recommended in the IPCC Guidelines. The IPCC Guidelines: Reporting Instructions establish:•

Standard tables, definitions, units, and time intervals for reporting all types of emissions;•

The necessary documentation to enable comparison of national inventories, including worksheets, major
assumptions, methodological descriptions, and enough data to allow a third party to reconstruct theinventory from national activity data and assumptions, and•An uncertainty assessment.

8

Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Sector workshops should discuss, on a source by source basis, the suitability of the IPCC tables, the key aspectsof an emissions estimate that should be reported or documented, and suggestions for improvement in light of thegoals of the good practice guidelines. Specifically, expert groups may want to consider the suitability ofreporting the following information for particular sources:•

An identification and description of the underlying method, including algorithms and equations;•

A discussion of methodological changes from previous years and the impact on estimates;•

Any and all assumptions made or exceptions taken to good practice in the light of the IPCC Guidelines;•

An analysis of the trends, with special emphasis on explaining anomalies;•

All activity data, including any permutations performed on standard data to derive a value used in the inventory;•

All emissions factors, including explanations of why emissions factors were changed from previous years;•

Complete bibliographical information for activity data and emissions factors, and•Results of the QA/QC programme and external reviews.

4

INVENTORY QUALITYASSURANCE/QUALITY CONTROLAn IPCC workshop on uncertainty and QA/QC issues in general will be held in October 1999 as part of thedevelopment of good practice guidance. Historically, the IPCC Guidelines have not devoted a lot of attention to
general QA/QC protocols although they were discussed at the Paris expert meeting in October 1998. The QA/QC
good practices that are ultimately developed should reflect practicality, acceptability, cost-effectiveness, existing
experience, and potential for codification in order to be implemented uniformly on a worldwide basis. For
purposes of the sector workshops, however, it will be important to consider when and how QA/QC proceduresshould be integrated into the development of the source-level inventory.
A successful QA/QC programme should have two distinct components. The first component is quality control(QC), which is a system of routine technical activities, implemented by inventory development personnel tomeasure and control the quality of the inventory as it is being developed. The QC system is designed to:•Provide routine and consistent checks and documentation points in the inventory development process toverify data integrity, correctness, and completeness;•

Identify and reduce errors and omissions;•

Maximise consistency within the inventory preparation and documentation process, and•Facilitate internal and external inventory review processes.

Quality control activities include technical reviews, accuracy checks, and the use of approved standardised
procedures for emission calculations. These activities should be included in inventory development planning,data collection and analysis, emission calculations, and reporting. For each source, experts should determine
which aspects most heavily influence the ultimate emissions estimate. It is on these sensitive aspects that QA/QC
usually needs to be targeted.
The second component of a QA/QC programme consists of external quality assurance (QA) activities, which
include a planned system of review and audit procedures conducted by personnel not actively involved in theinventory development process. The key is to have a review by an independent, objective third party to assess
the effectiveness of the internal QC programme and the quality of the inventory, and to reduce or eliminate any
inherent bias in the inventory processes. In essence, the QA programme ensures that the inventory QC process
was correctly performed. Different types of audits and reviews may be suitable for specific sources:•

Third party audit;•

Expert (peer) review;•

Stakeholder review, and•Public review.

A common thread throughout both of these components and, in fact, the whole QA/QC process, is the need forthorough documentation and complete transparency. Documentation and transparency are intrinsic to QA/QC

General Background Paper

9Background Paperand should not be separated. For example, a government agency responsible for compiling a national inventory
from regional offices or companies needs full documentation of this data and calculations in order to perform its
own QA. The agency also needs to document the national compilation process and the QC performed so that it istransparent to external reviewers and the UNFCCC. In short, each group should have the necessary information
with which to fulfill its function.
An effective QA/QC programme will include planning, numerous QC checks during inventory development, and
QA audits at strategic points in the process. Depending on the source, the exact QA/QC steps that should be
followed will vary; however, good practice for each source should consider the appropriateness of using thefollowing tools:•

Sample calculations: Reproducing a small set of calculations is a quick way to assess quality.

•

Sensitivity analyses: Sensitivity analysis helps to focus QA/QC efforts on the most important inputs.

•

Statistical checks: Is the data set representative?

•

Emissions validation: Is the final estimate consistent with other estimates?

•

Reality checks: Does the final estimate make sense? (e.g., Does the answer follow stoichiometric ratios, orconserve energy and mass?)

At the sector workshops, expert groups should describe any specific QA/QC issues related to their particularsource and determine if there are certain types of QA/QC activities that would be recommended for the source
based on its characteristics.

REFERENCES
Guidelines for the Preparation of National Communications by Parties included in Annex I to the Convention,
Part I: UNFCCC Reporting Guidelines on Annual Inventories (FCCC/CP/1999/7).
Intergovernmental Panel on Climate Change (IPCC) (1997). Revised 1996 IPCC Guidelines for National
Greenhouse Gas Inventories. J.T. Houghton et al., IPCC/OECD/IEA, Paris, France.
Intergovernmental Panel on Climate Change (IPCC) (1998). Meeting report: "Expert Group Meeting on
National Feedback on the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories" (15-16
September 1998 Havana, Cuba). IPCC/OECD/IEA, Paris, France.
Intergovernmental Panel on Climate Change (IPCC) (1998). Meeting report :"Expert Group Meeting on
Managing Uncertainties in National Greenhouse Gas Inventories" (13-15 October 1998 Paris, France).
IPCC/OECD/IEA, Paris, France.
United Nations Framework Convention on Climate Change (UNFCCC) (1996), Report of the Conference of theParties on its Second Session, held at Geneva from 8 to 19 July 1996: Addendum PART TWO: Action Taken
by the Conference of the Parties at its Second Session. FCCC/CP/1996/15/Add.1.
United Nations Framework Convention on Climate Change (UNFCCC) (1998), Report of the Subsidiary Body
for Scientific and Technological Advice on its Eighth Session (Bonn, 2-12 June 1998).
FCCC/SBSTA/1998/6.

10

Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

ANNEX 1CONSIDERATIONS FOR IMPLEMENTING GOOD
PRACTICE GUIDELINES

There are a number of important considerations to keep in mind as the inventory workshops proceed, specificallyin the context of how to implement good practice guidance for each sector or source category. Following is a listof these considerations with an explanation for each:•How can we instil good practice guidance into the IPCC Guidelines (i.e., for each sector and source
category, how do we develop a written and structured framework for good practice method approaches)?

It will be necessary to overlay the good practice guidance developed as part of these workshops onto the existing
IPCC Guidelines. Whereas no definitive format or means for implementing the good practice techniques has
been decided at this point, it would be practical to think in terms of how the existing IPCC Guidelines could
form the basis for communicating good practice techniques. Considering this type of application will also be
helpful in designing good practice guidance that meets the protocol objectives of the IPCC format.
•

Identifying priority areas for further technical review

In developing decision trees to select preferred methods, weaknesses in existing procedures will be identified
and may lead to investigations into areas for technical improvement in methods, emission factors, and/or activity
statistics. These areas for investigation should be prioritised to the extent possible in the workshops. The extent
to which these investigations can be carried out will need to be decided upon completion of the workshops andwith feedback from the parallel workshop on uncertainty issues.
•

Identifying key elements of good practice for each source

Within the sector workshops it will be critical to identify key elements of good practice for the available
methods. If the sector workshops can highlight those key elements that most significantly impact the quality ofemissions for a given source category, Parties can focus attention on those key elements to improve theirinventories. Also, if the workshops can point to any known deficiencies in key elements, this will accelerate theprocess to improving methods.
•

Coordination with parallel workshop on uncertainty

The attendees of the good practice workshops should be aware of the parallel IPCC workshop being held on
uncertainty assessment and management. That workshop will consider the development of a multi-tiered
methodology for the assessment of uncertainty. This methodology will include definitions of technical terms;
default methods for estimating uncertainty; and one or more higher Tier options which will include the use ofexpert judgement, appropriate measurements and a methodology (including probability distributions foremission factors and activity data) for combining these uncertainties. The uncertainty workshop will also
develop guidance for communicating these uncertainties to a non-technical audience.
•

Recognition of the diverse national conditions of data availability, resource constraints, and infrastructure

In developing initiatives and guidelines to improve inventory methods, it must be remembered that priorities
may differ by country in relation to the contribution that a particular sector makes to a country's nationalemissions. For example, a summary of the national feedback on the IPCC Guidelines from the September 1998
IPCC meeting held in Havana, Cuba, showed unique priorities at the source category level from country tocountry. The best approach to addressing these differences may be to establish groupings of categories andpriorities relative to countries with common characteristics or concerns.
•

Inventory improvement and refinement is often an iterative process, with feedback from QA review and endusers

The inventory data produced in response to the FCCC requirements and the Kyoto Protocol will have an
increasing number of end-users, and as a result, intensive review and commentary. As a result, the process bywhich inventories are developed becomes an iterative one, where review and usage provide feedback for
improvement to original emission estimates. Even after more formal review processes are in place for evaluating
fulfillment of commitments, there may be additional requirements for quality, uncertainty assessment, andreporting associated with other end uses such as emissions trading.

General Background Paper

11

Background Paper

ANNEX 2
1

FRAMEWORK FOR BREAKOUT GROUPS TWO PAGE
SUMMARIESMETHODOLOGICAL ISSUES

1a. Choice of Method
Good practice method is to use [country-specific measured data on emissions and assumptions wherever
possible]. This means that emission factors should reflect the specific conditions of a country and thetechnologies involved (including any emissions mitigation technologies), and be measured often enough toreflect the variability of the process to a level of accuracy [that would be provided by daily monitoringmeasurements to establish the relationship between emissions and production] although [experience has shownthat less frequent monitoring than this may be sufficient to give this level of accuracy].
[Continuous monitoring of emissions would also be consistent with good practice], but [is not regarded as
feasible].
Breakout groups should provide guidance on the choice of method (by decision trees), the selection ofparameter values which are linked to particular circumstances, situations in which national methods areappropriate, and propose corrections for any errors (see decision tree below)

Sample Decision Tree

For each subsource:

Note: This is the simplest form of adecision tree. Groups should expand/amend
it as necessay to reflect specificcircumstances

Identify sources andsubsources

Is the neseccary detailed data available?

Yes

Use “high data” good practice method

No

Is this an “important” source*NoIs necessary aggregate
data available

Yes

No

Obtain/develop necessary data
Obtain/develop
necessary data

Yes

Use aggregate ordefault good practicemethod*The process for determining whether a source is “important”
will be discussed subsequent to the sector meetings andacceptance of any such process is dependent on a decision of theParties

1b. Choice of emission factor
Good practice emission factors involve the measurements at the sources as described above. These should be
carried out using [describe instrumentation and measurement process]. The nature of the instrumentation and thefrequency of measurement will determine the associated uncertainty for typical measurements for this source, theassociated uncertainty is expected to be about [X] percent[Where complete coverage of variability within a source is not feasible, the inventory agency should establish
and describe whether the sample available is representative, and where not, take steps to establish representative
data for the missing variability/source, in the following manner...]Default emission factors are available in the IPCC methodology. If their use is essential because of lack ofmeasurements in national circumstances [groups should make recommendations about what good practice wouldbe, e.g. regionally specific defaults, technology dependent defaults, etc]
Default emission factors and associated uncertainty ranges could be arranged as in the following table:

12

Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories

Technology

Default emission factor

Associated uncertainty

A
B
Etc

1c. Choice of activity data
For the good practice method, activity data consist of production statistics which should be collected by[National Bureau of Statistics using yearly census data. These data should be comparable to international data
sources like IEA. Differences with IEA should be explained]. The accuracy will be [x percent ]/ [high comparedto the accuracy of the emission factor].
1d. Input to Uncertainty workshop[For this source good practice methods should permit determination of uncertainties using standard statisticalmethods][Uncertainties for this source have been estimated using expert judgement based on knowledge of theperformance of the engineering components involved].
1e. CompletenessComplete coverage for this category requires estimation of emissions from the following activities, where
present: [List them]
Experience has shown that the following sub-sectors may be missed in existing inventories and their presence
should be checked specifically [List any]
1f. Other Issues such as base line determination
If all the necessary historical data are present, the base year emissions estimate should be made using the goodpractice method.
Where some historical data are missing [it should still be possible to use source- specific measurement madeunder the good practice regime to establish an acceptable relationship between emissions and activity data in thebase year].
2

REPORTING AND DOCUMENTATION

The worksheets contained in the IPCC Guidelines [do/do not] provide transparent reporting. [To improvetransparency emissions estimates form this source should be reported [separately] as follows]
The following information is necessary to document the estimate in order to ensure transparency: [list items][Identify any issues that hamper reporting and documentation of emissions and recommend how to eliminate
barriers to reporting and documentation]
3

INVENTORY QUALITY ASSURANCE/ QUALITY CONTROL (QA/QC)[Say what kind of QA/QC records should be maintained at the plant/source level to allow auditing of themeasurements made, data records kept and the information supplied to the inventory agency][Identify any national or international data sets that could be used for comparison during review. These need not
be completely independent of the plant data][Say whether it would be feasible to cross-check emissions estimates form this source by external measurements]

General Background Paper

13