A modular sorting bin and the service that sells it
Product and digital service designed together for 10 waste categories
/images/waste-sorting-bin-and-service/wireflow.webp
A wireflow diagram in Danish mapping the website's screens from the homepage through product configuration to checkout
- Context
- Produktudvikling, faser og forløb, and Interaction Design, DTU
- Year
- 2021
- Role
- User research and usability testing
- Team size
- 6
- Tools
- Cultural probe · Workshop · Blue Ocean canvas · Weighted decision matrix · Material selection · Life cycle assessment · Service blueprint · Wireframes and wireflow · Usability testing · 3D modelling and rendering
- Contribution
- Team of 6, ethnographic user research and the usability testing
From 1 July 2021 every Danish household had to sort waste into 10 categories, and we designed both halves of the answer, being a modular stainless steel bin with movable divider plates that fits inside a kitchen cabinet, and the website that lets someone specify and order one. The bin was scored at 7.9 against two alternatives, and designing it to come apart raised what fits on a EU pallet from 36 units to 200.
The problem
From 1 July 2021 the same sorting rules applied in every Danish municipality, covering food, paper, cardboard, metal, glass, plastic, textile, cartons, residual waste and hazardous waste. This is a lot to fit in a kitchen, especially since a third of Danes live in flats, and less than 30% of household waste is currently recycled in most municipalities while industry recycles four times as much as households do. Furthermore each inhabitant produces 842 kg of household waste a year, so the volume is not small either.
Where the gap in the market was
We benchmarked the existing solutions, including IKEA HÅLLBAR, Brabantia BO Touch Bin, ENVI CENTER 3, Hailo Cargo, Copenhagen 3-30 and Pelly Flip, and mapped the field on a Blue Ocean canvas across sorting options, quality and sustainability. The gap that came out of it was a sorting system in high quality and in metal or other sustainable materials rather than plastic, which fits into a small kitchen while still offering many sorting options, and which sits in the high price bracket. Alongside this we ran a technology and patent scan covering bioplastics, folding mechanisms, metal 3D printing, monitoring systems and autonomous bins, in order to see what was already claimed.
Understanding how people actually handle waste
We ran a cultural probe where families photographed their kitchens, their existing bin solution and the bins just before emptying them, and logged the date, time and waste type each time they took the rubbish out along with why they did it at that moment, and we ran a workshop alongside it. It is important to note that this was during COVID-19, so we could not be invited into people's homes, and we had to make sure participants were comfortable sending pictures of a kitchen that might be messy. The findings that shaped the product were that the bin has to live under the sink, that people are used to sorting into three bins rather than ten, that 4 of the 10 categories are already stored somewhere other than the kitchen, that cardboard takes up a disproportionate amount of room, and that people are genuinely uncertain about what goes where. Furthermore the recurring complaints were that the bin takes up space, that waste smells, that it looks messy, and that existing bins are simply not attractive.
What I did
The group of six shared most of the work, and we all took part in the service blueprint, the storyboard and the ideation, however my own weight sat on the user research and especially on the testing. Here I worked on the ethnographic side, meaning the cultural probe and the follow-up questions that turned photographs into something we could actually read, and I leaned further into the usability testing of the digital prototype than the rest of the group did.
Choosing between three concepts
We set a criteria list before ideating, covering modularity, appearance, sustainability, smart division and at least 5 compartments, and then scored three concepts in a weighted matrix, being a cabinet with built-in bins where the countertop lifts, a bin with movable divider plates, and a bin hanging on the back of a door. The weights were usability at 30%, feasibility at 25%, quality at 20%, and novelty and sustainability at 12.5% each. The divider plate concept won at 7.9 against 6.6 and 5.8, and it won on usability and quality rather than on novelty, where it actually scored lowest of the three.
The product
A stainless steel body with grooves along the inside walls, so that divider plates can be moved in order to set how many compartments there are and how large each one is, which addresses the finding that people sort into three today and will have to sort into more later. The material came out of a study plotting CO2 emissions against price for candidates that had to be recyclable and resist water corrosion, and cold-worked austenitic stainless steel was chosen. Perforations across the body reduce material cost while giving the bin a distinct look, and two bins fit inside a single kitchen cabinet. A physical prototype was built to establish the dimensions and the groove spacing, and the design was then modelled and rendered in 3D, including in a kitchen context in order to check that it actually reads as something people would want under their sink.
Designed to be shipped flat
Because the bin comes apart, 200 units fit on a EU pallet against 36 assembled, which is a 5.5 times improvement on transport volume from a decision that was already being made for other reasons. Furthermore the life cycle assessment put the lifetime at 15 years and the transport at 4.5 kg CO2 per kg across trucks, ships and trains, with the body recyclable at end of life.
The service, designed alongside it
A customised product is only worth building if specifying it is not painful, so the ordering experience was designed in parallel in Interaction Design. We mapped it with a service blueprint, tested demand first with a pretotype in the form of a fake-door Facebook advertisement in order to answer whether people actually want to design their own sorting system, and then built a task flow, a wireflow and a low fidelity prototype covering the three things that mattered, being whether people could find the products, enter their measurements and complete a purchase.
What the usability test showed
The site was easy and intuitive to navigate, however the front page was confusing at first glance even though users worked it out quickly, and the cancel button was not intuitive at all, since users associated it with going back a page rather than emptying the basket, and the product was not removed from the page afterwards. The more useful limitation was that we could not properly assess whether the design created a good experience, due to the prototype being low fidelity with no colours, no images and nothing multimodal, which made it hard for a test user to judge how the site made them feel. Here I would run more iterations at a higher fidelity next time, and test whether people can actually measure their own kitchen cupboards and enter those numbers correctly, since that step is where the value of a customised bin either lands or falls apart.
What I would do differently
We reframed the problem too late, since we had already committed to a user-customised bin by the time we did it, which means the reframing did not do the job it is supposed to do, being to check that we were solving the right problem rather than a symptom. One of our own reframes pointed at excess packaging as the root cause instead, and we never followed it.
/images/waste-sorting-bin-and-service/hero.webp
3D render of the perforated stainless steel sorting bin pulled out from under a kitchen cabinet, with a divider plate visible inside
/images/waste-sorting-bin-and-service/prototype.webp
A white cardboard physical prototype of the bin, open at the top to show the internal divider compartments
/images/waste-sorting-bin-and-service/kitchen-context.webp
3D kitchen render showing the sorting bin installed under the counter beside the sink
/images/waste-sorting-bin-and-service/service-blueprint.webp
A service blueprint mapping customer actions, touchpoints, frontstage and backstage systems from arriving on the site through to placing an order
/images/waste-sorting-bin-and-service/ui-wireframes.webp
Low-fidelity wireframes of the BuildABin website on phone screens, showing the homepage and the product configurator with measurement inputs