Eco Audit White Paper. - Granta Design

Figure 8. The 1 st -life energy and carbon emissions, compared with potential end-of-life credit.When fossil fuel or electricity are convertedinto heat, there are no losses—the efficiencyis 100%. But when energy in the form of fossilfuel is converted to electrical energy theconversion efficiency is, on average 2 , about33%. The direct conversion of primary energyto mechanical power depends on the input: forelectricity it is between 85 and 90%; for fossilfuel it is, at best, 40%. Selecting an energyconversion mode causes the tool to retrievethe efficiency and multiply it by the power andthe duty cycle—the usage over the productlife—calculated from the life in years times thedays per year times the hours per day.Products that are part of a transport systemcarry an additional energy and CO 2 penalty bycontributing to its weight. The mobile modepart of step 3 gives a pull-down menu to selectthe fuel and mobility type. On entering theusage and daily distance the tool calculatesthe necessary energy.Step 4, the final step, clicking “report”completes the calculation. The Appendixshows example output.5. Case studiesAn eco audit is a fast initial assessment. Itidentifies the phases of life—material,manufacture, transport, and use—that carrythe highest demand for energy or create the2 Modern dual-cycle power stations achieve anefficiency around 40%, but averaged over all stations,some of them old, the efficiency is less.greatest burden of emissions. It points thefinger, so to speak, identifying where thegreatest gains might be made. Often, onephase of life is, in eco terms, overwhelminglydominant, accounting for 60% or more of theenergy and carbon totals. This difference is solarge that the imprecision in the data and theambiguities in the modeling are not an issue;the dominance remains even when the mostextreme values are used. It then makes senseto focus first on this dominant phase, since itis here that the potential innovative materialchoice to reduce energy and carbon aregreatest. As we shall see later, materialsubstitution has more complex aspects—thereare trade-offs to be considered—but for nowwe focus on the simple audit.This section outlines case studies that bringout the strengths and weaknesses of the EcoAudit Tool. Its use is best illustrated by a casestudy of extreme simplicity—that of a PETdrink bottle—since this allows the inputs andoutputs to be shown in detail. The casestudies that follow it are presented in lessdetail.Bottled waterOne brand of bottled water is sold in 1 literPET bottles with polypropylene caps (similarto that in Figure 9). A bottle weighs 40 grams;the cap 1 gram. Bottles and caps are molded,filled, transported 550km from the French Alpsto London, England, by 14 tonne truck,refrigerated for 2 days requiring 1 m 3 ofrefrigerated space at 4 o C and then sold.The CES EduPack Eco Audit Tool 8 © 2012, Granta Design