Appendix 3: Example of a Specific Life Cycle Assessment Comparison of Hand Drying Options
LCA, including its methodology, is guided by the ISO 14040 series of standards and includes four phases. First, the goal and boundary of the study is defined. Figure 10 provides an example of the boundary for a conventional hand dryer.
FIGURE 10. LIFE CYCLE SYSTEM BOUNDARY AND KEY REFERENCE FLOWS FOR THE CONVENTIONAL HAND DRYER
Source: Quantis 2009
Second, all of the inputs and outputs for a given product system throughout its life cycle are identified (often at the unit process level), compiled, and quantified in a Life Cycle Inventory (LCI). This information can be calculated by the person conducting the assessment or can be taken from an existing LCI database. Third, the results of the inventory analysis are interpreted in terms of their environmental impacts (e.g., climate change, resource use, human health, ecosystem quality, freshwater use). Figure 11 shows the relationship between the LCI results and the impact categories.
Finally, the environmental impacts from the entire life cycle are examined to identify hot spots or compared to other products, processes or technologies to determine the best option. The results can be represented with a single score, but there is debate about the accuracy of weighting factors required to reach this. Figure 12 shows the life cycle impacts of four hand-drying options in five different impact categories.
FIGURE 11. RELATIONSHIP BETWEEN LIFE CYCLE INVENTORY AND IMPACT ASSESSMENT CATEGORIES
Source: Quantis 2009
FIGURE 12. TOTAL LIFE CYCLE IMPACTS OF FOUR HAND DRYING OPTIONS
Source: Quantis 2009