How to design systems with their full environmental cost in mind, from raw materials to disposal, including the energy used by software. Press play on any sketch to watch it happen.
1 Life cycle assessment
A product's impact does not begin when you switch it on. Life cycle assessment measures the whole journey, so you improve the stage that matters and avoid moving the problem elsewhere.
The stages: raw materials, manufacturing, transport, use, and end of life.
Standard: ISO 14040 sets out how to run an assessment.
Hot spot: the stage with the biggest impact. It is often not the obvious one.
Burden shifting: fixing one stage in a way that makes another one worse.
Life cycle diagram
1/5 Metals and minerals are mined, which has its own energy and water cost.
Rule of thumb: Measure before you optimise. Hot spots often surprise people.
2 From linear to circular
The old model is take, make, throw away. A circular system keeps materials in use for as long as possible, and that has to be designed in from the start.
Reduce: use less material and energy in the first place.
Reuse and repair: keep the whole product working. This saves the most.
Recycle: recover the materials. It is the last resort, not the first.
E-waste: electronics contain valuable metals and hazardous ones, so proper handling matters.
Flow diagram
1/4 Linear: make it, use it, throw it away. Every new unit needs new material.
Rule of thumb: Design for repair: standard screws, replaceable batteries and available spare parts.
3 Sustainable computing
Software has no weight, but it does use electricity. Efficient code, sensible hosting and good timing all cut the energy and carbon behind a system.
PUE: power usage effectiveness: total data centre energy divided by IT energy. Closer to 1.0 is better.
Efficient code: less CPU, less data and fewer idle servers mean less energy.
Carbon-aware: run flexible work when and where the grid is cleanest.
Hardware lifetime: keeping devices working longer avoids the carbon of making new ones.
Scheduling diagram
1/4 A report job can run any time tonight, so it does not need to run right now.
Rule of thumb: Switching off idle servers is the easiest saving in computing, and it cuts the bill too.
