Emissions to air

Statistics Norway does only to a small extent collect data specifically for the emission inventory. The goal for data collection for the emissions inventory is that these statistics shall be based on already existing registers and statistics. However, it may be necessary to make some adjustments for this special purpose.

Data reported directly to the Norwegian Environment Agency (emission data from point sources, data from large industrial plants) are quality checked by the Norwegian Environment Agency. In addition, a consistency check is done by Statistics Norway. Statistics Norway is responsible for quality control of the activity data and emission figures from the model. Besides data from the energy balance, there are no particular controls performed on data from Statistics Norway's own statistics used in the emission calculations, as it is presupposed that the data already have been quality controlled.

The controls used in connection with the emission calculations can be divided into two parts:

1. Quality control and editing of input data, for example information about emissions per industrial plant from the Norwegian Environment Agency.

2. Quality control and editing of the emission figures (output from the model).

1. Quality control and editing of input data:

The possibility to check the input data varies, depending on the collection methods and who collects the data. The controls will mainly be:

*To compare data with figures reported from the same unit earlier

*To collect missing data

*To contact industrial plants regarding obvious errors or by asking questions about the reported figures

Lack of data in time series can be interpolated or filled in by use of estimates. The primary statistics in SSB are submitted to fixed quality control and editing routines. There is no additional control of primary data.

2. Quality control and editing of the emission figures (output from the model)

The national figures must be controlled source by source, by comparing with figures from previous years or figures for the same year calculated one year ago. Breaks in the series must be explained.

For comparisons between different calculations for the same year, the target is that all changes should be explained as change in data or method. For comparisons between different years, the target is to explain all large changes in the time series.

Annually, there are international examinations (reviews) of the emission inventory, performed by a group of experts nominated by IPCC .

The emission inventory is mainly based on calculations. Only a few industrial plants continuously measure their emissions. Some plants have periodic measurements that are scaled up to annual levels. For other plants and other sources than manufacturing industries, the emission figures are calculations, often of the type:

Emission = Activity data * emission factor

Activity data can be for example tonnes of fuel oil used by an industry, while the emission factor expresses the emission of a component in proportion to the activity (for example tonnes of SO 2 /tonne fuel oil). The emission factors are usually based on measured values, national or international.

The estimation methods are described in detail in National Inventory Report (NIR).

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