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University of Michigan - Ann Arbor
Civil And Environmental Engineering
CEE 265
Phillip Savage

CEE 265 November 12, 2013 The Midterm Exam is tomorrow evening from 7:00-9:00 in the same classrooms as last time. There will be four problems, the first will be a set of short answer questions and the other three will have multiple parts. He will post a formula sheet later today. It’s an open coursepack exam so you should bring that with you and any other notes you want. LIFE CYCLE INVENTORY Recap: we used metalworking fluids as an example of boundary setting and scoping.  We were talking about reference flow o Amount of product needed to fulfill the function o Measured by functional unit  Then we talked about the factors about data quality that needs to be considered o Allocation is important as well o If you trace back origins, sometimes raw materials come from processes that are producing many materials at once, not just one  So how much of the energy should be allocated to our metalworking fluid?  Or how much of the energy was used for other products?  It’s a judgment call basically o You can allocate either by mass produced or their relative value (price) Inventory Analysis  Adds up everything that comes in and out o Assembly of product, its use, and what happens at the end of life o Recycled or sent to landfill  Trace back all the sub-processes that contribute to the overall function o If you do this in detail you can spend a lot of time doing the inventory o So a spreadsheet is used to keep track of all the inputs for the product Impact Analysis  Human health impacts o Measured in terms of reduction of anticipated lifespan o As result of exposure to these substances  Ecosystem impacts o Eutrophication of lakes, destroying forests, habit displacement, etc o All of these are bundled into measures that can describe damage to environment  Resource depletion impacts o We have to start digging in harder access points as we use resources up o Takes more energy input to extract the resource Life Cycle Impact Analysis  Use the inventory to calculate the midpoint indicators o Midpoint indicators include things that would effect human health (smog, carcinogens, climate change, etc) o Also things that effect ecosystem quality (acidification, land use, etc) o Finally, a reduced resource base would be assessed with midpoint indicators (mineral use and fossil fuel consumption)  One example of life cycle methodology is the eco-indicator approach o We can add up the total amount of materials and fuel used o Calculate how much land is needed and direct amount of different emissions that we think may have a significant impact o Also do risk assessment of concentrations compared with daily air intake  Exposure models  Tells us midpoint levels of toxins that might be in a person  Or toxicity that the wildlife are exposed to o Damage analysis would be the last step  Take all the things that cause a reduction in the quality of life  Tie together in single bundle measure  Projects shortens lifespan of human population  Trying to relate emissions and concentration that result from a product to environment o Requires different types of modeling of the ecosphere portion o Risk assessment model for exposure to carcinogens for example o Subject to the same uncertainties as the inventory stage o We have to make a lot of assumptions  How do we prioritize the different indicators?  Where is damage most important? o Took survey and most people think ecosystem health is the most important  Not many people thought resource depletion was very important  Also a lot of human health concerns  But obviously there is no consensus even among experts Life Cycle Assessment: Interpretation  We again have to make a decision about which type of model to use  The interpretation then has several goals o Reiterate the level of analysis o Convey a level of confidence in the results o Indicate sensitivity analysis o Put forth some conclusions based on the analysis o Maybe make recommendations  An example of life cycle analysis: aluminum vehicles and global warming o Most of fuel expended is to move the car around o So if the car’s shell is build with lighter weigh
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