Design for a circular economy

Linear runs take, make, use, dispose — value created once and destroyed once. Circular is a closed loop where disposal becomes a return and resources are continuously repurposed.

Maintain keeps everything; reuse nearly everything; repair keeps the assembly; remanufacture keeps the parts; recycling keeps only the material.

It was designed to be thrown away and then partly rescued. Circular means the return was designed in — bolted not glued, separable materials, and a business that wants it back.

The embodied energy of forming and assembling a product is usually far larger than the energy in its raw material, so keeping the artefact is worth more than keeping the substance.

Longevity, upgradability, disassembly and dematerialization — with longevity first, because doubling the time in use halves everything else.

"Separated into material streams in under five minutes with standard tools", tested with a prototype, a screwdriver and a timer, by somebody who has not seen it before.

One unobtainable part. A product engineered for ten years with a five-year spares policy is a five-year product.

Extraction and processing waste ore, water and energy far exceeding the mass of the finished part, and manufacture adds offcuts, sprues and rejects.

A technical cycle, where metals and polymers are recovered and remade, and a biological cycle, where materials return safely to natural systems.

Where a product is used once, contaminated in use, lost during use, or too small to sort — situations where collection for the technical cycle cannot happen.

Degradable only breaks into smaller pieces. Biodegradable is converted by micro-organisms to water, carbon dioxide and biomass. Compostable is biodegradable within a defined time with no toxic residue.

A durable product should last; decomposition undermines the property that makes it sustainable. One recyclable polymer with a twenty-year life beats it on every account.

Reuse keeps everything; repair keeps the assembly; remanufacture keeps the parts; recycling keeps only the material. Take-back legislation keeps nothing itself but opens the route.

Standard fixings rather than glue or welds, a documented procedure, and spares available for the whole product life. A short spares policy cancels the design work.

It can require collection but cannot open a glued box or separate a bonded laminate. Every route depends on a design decision taken years earlier.

Rental and leasing, deposits and trade-ins, selling an outcome rather than an object, and producer responsibility — all of which make the return profitable rather than a cost.

Solar, wind, hydro and tidal, biomass and biofuel, and geothermal — each with a limit, which is why a real grid uses several.

Every loop involves collection, transport, sorting, cleaning, remanufacture and redistribution, none of which is free — and for a low-value material it can cost more than the material is worth.

The same material is moved and processed many times. If each movement burns fuel, the total emissions can exceed those of a single new item.

You cannot run a closed material loop on an open energy loop. If the energy is consumed and gone, the system is only half circular.