Experiences of environmental performance evaluation in the cement industry. Data quality of environmental performance indicators as a limiting factor for Benchmarking and Rating

Although ISO 14031 gives guidelines for environmental performance evaluation, there is limited experience of applying the standard in the area of benchmarking and external rating, especially when limitations of data quality are considered. This paper evaluates the importance of the data quality of operational performance indicators (OPIs, in this case emission factors) as a limiting factor for benchmarking and external rating between six cement plants in Sweden, Norway and Finland for three types of emissions, dust, NO_x and SO₂. Monthly emission factors for 1993–1999 were collected for these plants and a quality assurance process was undertaken to eliminate factors that decreased comparability. The data were tested against six hypotheses concerning different aspects of the variation of the emission factors. One of the findings was that there is no sharp limit when the quality of emission factors is high enough to make it possible to compare, since quality is a qualitative conception in itself. Instead, organisations using emission factors should strive to adapt a system with quality assurance of emission factors, resulting in widely accpeted emission factors suitable for comparison between plants. This is achieved with a sector specific methodology which can handle irrelevant differences and reflects real differences in environmental performance.