The most exacting and accurate framework for assessing solutions is Life Cycle Analysis (LCA), an entirely quantitative approach (see Figure 3.9). There are several variations of LCA tools, but conceptually they are largely the same. LCAs are usually expensive, timeconsuming, and difficult (if not impossible) to perform, but they deliver the most accurate and useful evaluation of materials and energy use.
Measurement of energy and material use throughout lifecycle
FIGURE 3.9. http://www. flickr. com/photos/rosenfeldmedia/3258180961 The full life cycle of a product or service includes many phases.
Strengths: Comprehensive, objective, easier to measure for existing products and services, rather than for proposed ones.
Weaknesses: Doesn’t adequately address financial or social analyses. Difficult, timeconsuming, and costly to perform. Most of the data needed for adequate evaluations aren’t available from organizations. Can’t be adequately performed in the design and prototype stages of development.  
• Interpreting the results to help you make a more informed decision”
This requires the examination of the materials and energy consumed and emissions produced at each stage of a product’s life, from the procurement of raw resources through manufacturing, transportation, and selling, throughout use, and finally to disposal and recycling (see Figure 3.10). (Ideally, everything would be recycled completely.)
FIGURE 3.10. http://www. flickr. com/photos/rosenfeldmedia/3258175023 The full life cycle of a product or service includes many phases.
Every choice in a product’s development affects its impact. These can include process choices (such as where and how to manufac-
ture a component), transportation choices, and material choices (what each component is made from). For example, transporting products great distances via train is usually more efficient (and has less impact) than transporting them via truck or airplane. Also, some materials, like aluminum and stainless steel, have far bigger impacts than PET plastic and paper. Wise choices during development can make a big difference in the resulting environmental impact.
Energy, materials, and other inputs are consumed at each step of a product or service’s life cycle. Also, at each step, emissions to the air and water, plus material waste, are generated along with the intended products and components. These all weigh into the impact. Even seemingly simple products can create deeply complicated LCA requirements.
A thorough LCA looks at the process and location for sourcing raw materials (including mining, processing, purification, and transportation). Metals, in particular, often require
processes that heat raw materials several times, casting them into some other form (such as slugs or ingots), transporting them to other facilities (requiring storage, distribution, processing, or manufacturing), reheating them and recasting them into parts, and then transporting them again in a lengthy cycle. The simplicity we think we see in finished parts (or intend in our designs) often masks an even greater complexity in process, as well as material and energy use, that may total from 30-50 percent of the product’s impact.
Packaging, too, represents a surprisingly high percentage of the materials and energy impact for many products. Consider the packaging costs for a bottle of perfume—the energy and materials that go into manufacturing the bottle, the label, and the series of boxes it will be shipped in can be staggering compared to the perfume contained within.