11-CS-3 Engineering Management · May 2018
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — May 2018 — 11-CS-3 Sustainability, Engineering and the Environment. Open book; non-communicating calculator permitted. Any four questions constitute a complete paper; all questions are of equal value (25 marks each).
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.
Complex, highly ordered materials embody large processing energy, so that investment should be preserved through reuse or remanufacture. Example: remanufacturing a complex component (an engine, a printer cartridge, an electronic module) preserves its embedded complexity, whereas shredding it to base materials destroys it—preventing the pollution and energy of making it anew.
Design a product to last its intended service life and no longer, so it does not persist as waste afterwards. Example: agricultural mulch film or food-service ware made from a certified-compostable polymer instead of conventional polyethylene: it performs for one growing season or one meal, then biodegrades, rather than persisting for centuries as microplastic pollution in soil and water.
Pollution prevention reduces or eliminates waste at the source rather than treating it afterward. It cuts operating costs by (1) lower raw-material and energy costs—using less input per unit directly reduces purchasing and utility bills—and (2) lower waste-management, treatment, and compliance costs—avoiding the expense of treating, storing, transporting, and disposing of waste plus regulatory fees and liability. P2 thus often pays for itself.
(i) Functional unit: drying one pair of hands (or all hand-dryings in the school over a defined period)—so the recurring paper-towel consumption is compared fairly with the durable drier. (ii) Stages: raw materials; manufacturing; distribution; use; end-of-life. (iii) Higher-impact alternative by stage: in raw materials/manufacturing, paper towels are worse per functional unit (paper/pulp consumed at every use), whereas the drier is manufactured once; in the use phase, the electric drier dominates (electricity for the heater/blower every use); in distribution, the recurring delivery of bulky paper is worse for towels; at end-of-life, paper towels generate continuous waste (landfill/compost) while the drier is a one-time disposal. (iv) Stage of greatest impact: for paper towels, the recurring raw-material/manufacturing (and waste) stage; for the electric drier, the use (electricity) stage. Which is greener depends on the cleanliness of the electricity and towel usage—on a clean grid the drier usually wins over its long life.
Design for disassembly: designing products to be easily taken apart for repair, reuse, or recycling. Industrial ecology: designing industrial systems like ecosystems so one process's waste is another's input. Resilience: the capacity of a system (ecological, engineered, or social) to absorb disturbance and recover its function—an increasingly important design goal under climate change. Biomimicry: designing solutions by emulating nature's models, systems, and strategies (e.g. cyclical, waste-free material flows). Source reduction: reducing waste and pollution at the point of generation (the top of the waste hierarchy). Intangibles: real but hard-to-quantify costs/benefits such as reputation or quality of life.
