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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 Guidance (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 Guidance)

For the 2005 inventory the Tier 1 level and trend assessment were applied including the LULUCF sector and excluding the LULUCF sector (IPCC 2000, 2003). 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 Guidance (IPCC, 2000). Key categories are defined as those categories whose cumulative percentage s, when summed in decreasing order of magnitude, contributed 95 per cent of the total level or trend.

A1.2 Disaggregation

The classification of categories follows the classification outlined in table 7.1 of Good Practice Guidance (IPCC, 2000). The category classification follows Good Practice Guidance 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-ULUCF table 5.4.1.

There was one modification to the suggested categories to reflect New Zealand’s national circumstances. The “fugitive emissions from fuels–oil and natural gas” 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 from Good Practice Guidance) showing results of the key category level analysis for 99 per cent of the total emissions and removals in 2005. Key categories are those that comprise 95 per cent of the total

View results of the key category level analysis for 99 per cent of the total emissions and removals in 2005 (large table)

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

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

Table A1.3 (table 7.A2 from Good Practice Guidance) showing results of the key category trend analysis for 99 per cent of the total emissions and removals in 2005. Key categories are those that comprise 95 per cent of the total

Results of the key category trend analysis for 99 per cent of the total emissions and removals in 2005 (large table)