Materials, Selection &
Sustainable Systems
Use material evidence to make design decisions—then test those decisions against sustainability and circular-economy strategies.
By the end of class, you should be able to…
Classify accurately
Use origin, property classes and structural forms correctly.
Recall key properties
Distinguish physical, chemical and mechanical terms.
Select with evidence
Include aesthetics, cost, availability, sustainability and research.
Think in systems
Apply sustainable-design and circular-economy strategies.
By property type
Physical, chemical and mechanical properties organize how materials behave.
By source / origin
Natural and human-made material families: timbers, polymers, metals, glass, textiles, composites, smart materials and biomaterials.
By structural form
The guide’s A3.1.2 also names frame, shell, solid and combination structures—how material is arranged in a product.
Density
Mass per unit volume.
Thermal expansion
Dimensional change with temperature.
Thermal conductivity
Ability to conduct heat.
Melting point
Temperature where solid changes to liquid.
Electrical resistivity
Opposition to electrical current.
Electrical conductivity
Ability to conduct electrical current.
Corrosion resistance
Ability to resist chemical/electrochemical degradation.
Reactivity / food safe
How readily the material chemically interacts; suitability for food-contact contexts matters.
Hygroscopy
Tendency to absorb moisture from the environment.
Flammability
Ease with which a material ignites/burns.
Loads / resistance
tensile strengthcompressive strengthstiffnesstoughnesshardnessShaping / deformation
malleabilityductilityplasticityRecovery
elasticityDo not use “strong” as a substitute for the property actually required.
Composite
Two or more materials are combined to create a property set more suitable for the purpose/context.
Smart material
A property changes significantly in response to an environmental stimulus.
Biodegradable / biomaterial
Can break down after useful life; important to circular strategies when designed into an appropriate system.
Piezoelectricity
Mechanical stress ↔ electrical response.
Shape memory
Returns toward a programmed shape under stimulus.
Photochromicity
Changes optical appearance with light.
Magneto-rheostatic
Flow/viscosity changes with magnetic field.
Electro-rheostatic
Flow/viscosity changes with electric field.
Thermoelectricity
Temperature difference and electrical energy are linked.
Properties
Physical + chemical + mechanical fit.
Aesthetics
Texture, form, colour and finishing techniques.
Context
Cost, availability and sustainability.
Research
Justify choices using appropriate primary + secondary evidence.
Reusable school water bottle
Needs low mass, impact resistance, safe food contact, repeated washing, pleasant grip and reasonable cost.
Five principles
cyclicsolarsafeefficientsocialDesign decisions
wastepollutionenergy consumptionPeople · profit · planet
conflictcompromiseprioritizationDesign out waste
Longevity, upgradability, disassembly, dematerialization.
Use better loops
Biodegradable materials where appropriate.
Recover value
Take-back, reuse, repair, recondition, recycling.
Power the loop
Renewable energy such as solar, wind, hydro or other renewable sources.
| Linear approach | Circular-economy approach |
|---|---|
| Extract → make → use → dispose | Keep products/components/materials in use through closed loops. |
| End-of-life often treated as waste | End-of-use becomes a recovery, reuse, repair or recycling opportunity. |
| Value is lost at disposal | Design tries to preserve material/product value. |
A product uses very little energy during use but is permanently bonded and impossible to repair.
Redesign a replaceable bicycle-light housing.
Before you leave…
Product Analysis & Design Evaluation — Synthesis
Keep the retrieval loop moving: recall → apply → check → correct → revisit.
Cumulative synthesis of A3.1, B3.1, C2.1 and C2.2: material classifications and all required physical/chemical/mechanical properties; structural forms named in A3.1.2; composites, smart and biodegradable materials; aesthetics/cost/availability/sustainability/research-based selection; Datchefski principles, TBL and circular-economy strategies.