MYP Design Life Cycle Analysis Notes

Life Cycle Analysis Counts the Whole Life, Not the Shop Price

1. Life cycle analysis adds up the energy used, the materials taken and the pollution released by a product across its entire life, from digging the raw material out of the ground to throwing the finished object away.
2. The price on the shelf hides nearly all of that, which is why a 2 pound cotton tote and a 5 pence plastic carrier have histories that look nothing alike.
3. The usual name for the full span is cradle to grave, and when the material goes back into a new product instead of a tip it becomes cradle to cradle.
4. The method exists because intuition gets it wrong, since most people assume paper always beats plastic and the honest answer depends on how many times each one is used.
5. A full professional study follows the ISO 14040 standard, takes months of data gathering and costs a company real money.
6. What you need is the structure of that thinking, so your evaluation compares two options fairly rather than picking whichever one looks greener.

Six Stages, From a Hole in the Ground to a Bin

1. Raw material extraction is mining, drilling, quarrying, felling or farming, and it is where habitat loss and land damage mostly happen.
2. Processing turns the raw stuff into usable material, smelting ore into metal, cracking crude oil into polymer granules, pulping timber into board.
3. Manufacture shapes the material into parts and assembles them, spending machine energy and cooling water and leaving offcuts behind.
4. Distribution moves the product and its packaging, cheaply in bulk by ship and expensively in ones and twos by diesel van to a doorstep.
5. Use covers everything the owner spends while they own it: electricity, fuel, water, detergent, replacement batteries and repairs.
6. Disposal is the ending, which will be landfill, incineration, recycling or, for a small number of products, remanufacture.
7. Processing is usually the heaviest stage for metals and polymers, because that is where ore becomes metal and crude oil becomes plastic.

What an LCA Actually Measures

1. An LCA counts inputs such as energy, water, ore and land, and outputs such as carbon dioxide, solid waste, water pollution and waste heat.
2. It needs a functional unit, a stated job the comparison is about, so you compare one year of carrying shopping rather than one bag against one bag.
3. It needs a boundary, a line saying what is counted and what is left out, such as whether the factory workers' journeys are included.
4. The result is several separate numbers rather than one score, because a material can win on carbon and lose heavily on water use.
5. Every study rests on assumptions, so two careful analyses of the same product can disagree simply because they assumed different lifetimes.
6. Read the assumptions before the conclusion, since a study that assumes a cotton bag gets used 200 times reaches the opposite verdict from one that assumes 20.

Embodied Energy: The Bill the Material Arrives With

1. Embodied energy is the total energy needed to produce one kilogram of a material, counting extraction, refining and transport, before the product has been made at all.
2. Aluminium is so expensive in energy terms because separating it from bauxite needs electrolysis, which means running a huge electric current through molten ore.
3. Recycling changes the figure most for metals, because remelting scrap is far easier than tearing an oxide apart.
4. Mass matters as much as the rate, so 20 g of aluminium can carry less embodied energy than 500 g of timber even though its figure per kilogram is twenty times higher.
5. Multiply the mass of each part by the figure for its material and you have a rough total that is good enough to compare two of your own designs.
6. It is quoted in megajoules per kilogram, written MJ/kg, and the gap between common materials is enormous rather than marginal.

Carbon Footprint Squeezes Everything Into One Number

1. A carbon footprint converts every greenhouse gas a product releases into a single figure, given as kilograms of carbon dioxide equivalent, written kg CO2e.
2. The conversion is needed because methane traps far more heat per molecule than carbon dioxide, so each gas is weighted before the totals are added.
3. Carbon footprint and embodied energy usually rise and fall together, but not always, because the same megajoule from hydroelectricity and from coal carry very different carbon.
4. That is why an aluminium smelter in Iceland running on geothermal power turns out metal with a much smaller footprint than an identical smelter burning coal.
5. One number is easy to compare and easy to misuse, since it says nothing about water, toxicity, habitat or the people who did the work.
6. Treat it as one measure alongside others rather than the whole verdict on a design.

Comparing Two Designs Across Their Whole Life

1. Compare the whole life rather than the moment of sale, because the option that is lighter and cheaper at the till often loses once use and disposal are added.
2. A ceramic mug carries far more embodied energy than a paper cup and only overtakes it after roughly 20 to 50 uses, depending entirely on how it is washed.
3. Washing decides that crossover, since a mug rinsed under a hot tap for a minute can spend more energy per use than the cup it replaced.
4. A kettle with a better element costs more energy to make and less to run, so the crossover depends on whether it boils twice a day or twelve times.
5. Lay the comparison out as a table with one row per life cycle stage and one column per option, then mark which option wins each row.
6. State the lifetime you assumed, because that single assumption usually decides which design comes out ahead.