حسابداری اثرات بوم شناسی در ارزیابی چرخه عمر محصولات

We present and discuss ecological footprint (EF) calculations for a large number of products and services consumed in the western economy. Product-specific EFs were calculated from consistent and quality-controlled life cycle information of 2630 products and services, including energy, materials, transport, waste treatment and infrastructural processes. We formed 19 homogeneous product/process subgroups for further analysis, containing in total 1549 processes. Per group, the average contribution of two types of land occupation (direct and energy related) to the total EF was derived. It was found that the ecological footprint of the majority of products is dominated by the consumption of non-renewable energy. Notable exceptions are the EFs of biomass energy, hydro energy, paper and cardboard, and agricultural products with a relatively high contribution of direct land occupation. We also compared the ecological footprint results with the results of a commonly used life cycle impact assessment method, the Ecoindicator 99 (EI). It was found that the majority of the products have an EF/EI ratio of around 30 m2-eq. yr/ecopoint ± a factor of 5. The typical ratio reduces to 25 m2 yr/ecopoints by excluding the arbitrary EF for nuclear energy demand. The relatively small variation of this ratio implies that the use of land and use of fossil fuels are important drivers of overall environmental impact. Ecological footprints may therefore serve as a screening indicator for environmental performance. However, our results also show that the usefulness of EF as a stand-alone indicator for environmental impact is limited for product life cycles with relative high mineral consumption and process-specific metal and dust emissions. For these products the EF/EI ratio can substantially deviate from the average value. Finally, we suggest that the ecological footprint product data provided in this paper can be used to improve the footprint estimates of production, import and export of products on a national scale and footprint estimates of various lifestyles.