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Annex 1: Key categories

A1.1 Methodology used for identifying key categories

The key categories in the New Zealand inventory have been assessed according to the methodologies provided in Good Practice (IPCC, 2000). The methodology applied was determined using the decision tree shown in Figure A1.1.

Figure A1.1 Decision tree to identify key source categories (Figure 7.1 from Good Practice)

For the 2004 inventory the Tier 1 Level and Trend assessment were applied including the LULUCF sector and excluding the LULUCF sector as per GPG LULUCF. The "including LULUCF" level and trend assessments are calculated as per equations 5.4.1 and 5.4.2 of GPG LULUCF. The "excluding LULUCF" level and trend assessments are calculated as per equations 7.1 and 7.2 of Good Practice (IPCC, 2000). Key categories are defined as those categories whose cumulative percentages, when summed in decreasing order of magnitude, contributed 95 percent of the total level or trend. Categories occurring between 95 percent and 97 percent of the cumulative total were qualitatively assessed whether they are should be regarded as key categories.

A1.2 Disaggregation

The classification of categories follows the classification outlined in Table 7.1 of "Good Practice" (IPCC, 2000). The category classification follows good practice by:

  • identifying categories at the level of IPCC categories using CO2 equivalent emissions and considering each greenhouse gas from each category separately
  • aggregating categories that use the same emission factors
  • including LULUCF categories at the level shown in GPG LULUCF Table 5.4.1.

There was one modification to the suggested categories to reflect New Zealand's national circumstances. The fugitive emissions from oil and gas operations category was divided into two categories: fugitive emissions from oil and gas operations and fugitive emissions from geothermal operations. This is to reflect that New Zealand generates a significant amount of energy from geothermal sources that cannot be included as oil or gas operations.

A1.3 Tables 7.A1-7.A3 of the IPCC good practice guidance

Table A1.1 (Table 7.A1 of Good Practice) showing the results of the key category level analysis for 99 percent of the total emissions and removals in 2004. Key categories are those that comprise 95 percent of the total.

View the results of the key category level analysis for 99 percent of the total emissions and removals in 2004 (large table).

Table A1.2 (Table 7.A1 of Good Practice) showing the results of the key category level analysis for 99 percent of the total emissions and removals in 1990. Key categories are those that comprise 95 percent of the total.

View the results of the key category level analysis for 99 percent of the total emissions and removals in 1990 (large table).

Table A1.3 (Table 7.A2 of Good Practice) showing the results of the key category trend analysis for 99 percent of the total emissions and removals in 2004. Key categories are those that comprise 95 percent of the total.

View the results of the key category trend analysis for 99 percent of the total emissions and removals in 2004 (large table).