11-CS-3 Engineering Management · May 2013
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
A highly processed, complex component embodies large amounts of energy and material refinement, so it is wasteful to shred it back to raw material. The principle says such complexity should be preserved through reuse or remanufacture. Example: an automobile engine or a laser-printer cartridge contains high embedded complexity; remanufacturing it—cleaning, replacing worn parts, and returning it to service—retains that invested complexity and prevents the pollution and energy use of manufacturing a new one from raw materials. Recycling the metal to scrap would destroy the embedded value; reuse conserves it.
A product should be designed to last exactly as long as its intended service life—no longer—so that it does not persist as waste beyond its usefulness. Example: single-use food packaging made from a compostable/biodegradable polymer (e.g., PLA) rather than a permanent plastic: it is durable enough to protect the food through its short use, then breaks down harmlessly, preventing the persistent-litter and landfill pollution that an "immortal" plastic would cause. Designing an over-durable product for a short-life application needlessly commits resources and creates lasting waste.
Products made of many bonded, dissimilar materials are hard to separate and therefore hard to recycle, so their materials are usually lost. Example: designing a beverage container or product housing from a single polymer (mono-material design) rather than a multilayer laminate of different plastics and foils. A mono-material package can be cleanly recycled into new material, whereas a multilayer laminate cannot be economically separated and goes to landfill or incineration—so material unification prevents that waste and retains value.
Industrial Ecology models an industrial system on a natural ecosystem, in which the waste of one organism becomes the food of another so that materials cycle and nothing is truly "waste." For this to work, the material and energy flows exchanged between processes must be non-hazardous: only then can one facility's by-products safely become another's feedstock (industrial symbiosis). If outputs are toxic, they cannot be recirculated and must instead be treated and disposed of, breaking the cycle. Thus ensuring inputs and outputs are inherently non-hazardous is what enables the closed-loop, waste-as-food networks that define industrial ecology (as at the Kalundborg eco-industrial park).
A good functional unit must express the equal service delivered, not merely equal mass: for example, "the quantity of shingles required to weatherproof 100 m² of roof over a 50-year building service life, including any replacements needed within that period." This is essential because the two materials have different lifespans—if cedar must be replaced more often than the recycled-plastic shingle, comparing them per unit area without accounting for durability would be misleading. As to the stage of greatest impact, for a durable roofing product the dominant burdens usually fall in the raw-material acquisition and manufacturing stage (harvesting and processing cedar, or collecting, cleaning, and re-forming recycled plastic), because the use phase of a passive roof consumes little energy. The answer depends on service life: a short-lived material shifts impact toward replacement (more manufacturing cycles), so the durability captured in the functional unit directly determines which product has the lower life-cycle impact.
