This paper has constructed a comparable CFP assessment sys-tem and framework that contains almost all the main processes in the life cycle of a shirt. The assessment method from bottom to top, based on the life cycle methodology, has offered the specific calculation to an integrated assessment of the CFP of shirts. The methods in this research are also appropriate to the production of many other textiles in China. Additionally, the conversation factors estimated in this paper have been appropriate to the assessment of other products.
The results showed that the average CFP of a pure cotton shirt produced in China, throughout its life cycle, was 8.771 kgCO2e, of which the indirect CFP of 8.423 kgCO2e is much higher than the direct CFP of 0.347 kgCO2e. Within the textile life cycle, the in-dustrial production stage have represented the largest proportion of CFP; the sub-process of industrial production have been cate-gorized as weaving, spinning, and clothing; and indirect CFP com-prises the main component of the industrial production CFP. The production stage (including agriculture and industrial production) have accounted for more than 90% of the total CFP.
Based on the investigation of industrial production and scenario planning of some processes in the life cycle, the assessment process and results in this paper could reasonably reflect the average CFP values for large-scale production of shirts in China. The results could partially represent the present situation for carbon emissions within the Chinese textiles sector; and could also support processes to manage the carbon footprint in the related companies, and provide some basic data to guide more sustainable patterns of consumption. However, it must be pointed out that the CFP estimated in this research does not imply a specific carbon responsibility for China. More significant to this paper is that the assessment system and framework in this work provide a more focused approach to the assessment of textiles or other products in China.
The bottom-up assessment methodology in this study based on direct data from detailed process in life cycle has clarifying the specific system boundary. Result of CFP by such methodology can
C. Wang et al. / Journal of Cleaner Production 108 (2015) 464e475472
be disassembled and reassembled, which make it possible to compare the results from different assessments of similar products. Contrastively, the CFP assessment result by the top-down meth-odology is mainly based on the allocation of gross data, which is difficult to compare among different assessments due to the dif-ference of system boundary and difficulty to disassemble and reassemble. The obstacle of the bottom-up assessment methodol-ogy is difficulty in data collection, that's why there are few CFP assessment cases by such methodology till now. Another difficulty in application of this methodology is its high requirement on data accuracy, because the result error would be unacceptable and even exceed that by top-down methodology due to error accumulation of inaccurate data. Likewise, we had difficulties in data collection in this study, and had to treat some data by estimation and allocation, especially in data of equipment or process without individual metering. Therefore, we testified those data by upper level direct metering data in every data collecting process to ensure the reli-ability of result.
As one of the important mechanisms for controlling and man-aging emissions of GHGs, comparisons between different fungible products and between the same products from different producers could help to reduce production CFP across the whole of society. Future assessments of fungible products, for example comparisons of T-shirts or shirts containing cotton or wool, should be conducted using a consistent framework and reporting methodology in order
to encourage consumers to select those associated with lower-carbon production. Comparison of the same products from different producers requires higher-resolution methods, frame-works, and data. In terms of the actual CFP assessment, producers have insufficient experience of measuring and collecting basic data, and the available data also lack sufficient accuracy to support comparisons between different producers. Further work to reinforce basic data measurement and the assessment of CFP in each process of a product life cycle would expand the application of production CFP assessment and provide databases for the routine application of CFP toward the management and reduction of GHG emissions.
Acknowledgments