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The CES EduPack Eco Audit Tool ? A White Paper - MAELabs UCSD

The CES EduPack Eco Audit Tool ? A White Paper - MAELabs UCSD

Figure 7.

Figure 7. The Eco Audit Tool © 2009 Granta Design Ltd. 6 MFA, 18/02/2009

5. Case studies An eco audit is a fast initial assessment. It identifies the phases of life – material, manufacture, transport and use – that carry the highest demand for energy or create the greatest burden of emissions. It points the finger, so to speak, identifying where the greatest gains might be made. Often, one phase of life is, in eco terms, overwhelmingly dominant, accounting for 60% or more of the energy and carbon totals. This difference is so large that the imprecision in the data and the ambiguities in the modeling, are not an issue; the dominance remains even when the most extreme values are used. It then makes sense to focus first on this dominant phase, since it is here that the potential innovative material choice to reduce energy and carbon are greatest. As we shall see later, material substitution has more complex aspects – there are trade-offs to be considered – but for now we focus on the simple audit. This section outlines case studies that bring out the strengths and weaknesses of the Eco Audit Tool. Its use is best illustrated by a case study of extreme simplicity – that of a PET drink bottle – since this allows the inputs and outputs to be shown in detail. The case studies that follow it are presented in less detail. Bottled water. One brand of bottled water is sold in 1 liter PET bottles with polypropylene caps (similar to that in Figure 8). A bottle weighs 40 grams; the cap 1 gram. Bottles and caps are molded, filled, transported 550km from Evian in the French Alps to London, England, by 14 tonne truck, refrigerated for 2 days requiring 1 m 3 of refrigerated space at 4 o C and then sold. Table 1 shows the data entered in the Audit Tool. Figure 8. A 1 litre PET water bottle. The calculation is for 100 units. What has the tool done? For step 1 it retrieved from the database the energies and CO2 profiles of the materials and the processes 3 . What it found there are ranges for 3 Data are drawn from the CES EduPack Level 2 or 3 database, according to choice. the values. It created the (geometric) mean of the range, storing the values shown below: Material and primary manufacturing process Table 1: The inputs Product name: PET bottle, bill of materials. Life: 1 year. Step 1: Materials and manufacture: 100 units Component name Material Process Mass (kg) Bottle, 100 units PET Molded 4 Cap, 100 units PP Molded 0.1 Dead weight (100 liters of water) Step 2: Transport Stage name Transport type Transport of filled bottles Water 100 Embodied energy (MJ/kg) Distance (km) 14 tonne truck 550 Step 3: Use phase: static mode – refrigeration i Energy input and output Electric to mechanical Power rating (kw) Step 4: Energy selected. Usage (hr / day) CO 2 footprint (kg/kg) PET, material 84 2.3 PP, material 95 2.7 Polymer molding 6.8 0.53 Usage (days / year) 0.12 24 2 i The energy requirements for refrigeration, based on A-rated appliances are 10.5 MJ/m 3 .day for refrigeration at 4 o C and 13.5 MJ/m 3 .day for freezing at -5 o C. The use energy is chosen to give the value for refrigeration. It then multiplied these by the mass of each material, summing the results to give total energy and carbon. For step 2 it retrieved the energy and CO2 profile of the selected transport mode from a look-up table (see Appendix A), finding: © 2009 Granta Design Ltd. 7 MFA, 18/02/2009

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