Interaction design · Sustainability
A mobile app that makes buying, renting and swapping second-hand clothes feel easy, social and a little bit fun.
The brief
Fashion drives close to 10% of global carbon emissions. With two fellow students, I designed an app that tackles this at the everyday level, letting people buy, rent and swap second-hand clothes, with gamification to make it engaging.
A course exam for our MSc in Human-Computer Interaction, mapping to UN SDG 12.
Research
A survey through Nettskjema covered habits, interest in an app, and attitudes to gamification. People wanted something simple and trustworthy, and a few raised hygiene concerns about second-hand, a sign that trust would matter.
54
responses, refined to ages 18–31
80%
interested in a second-hand app
58%
buy second-hand for sustainability
Mixed
views on leaderboards & points
Define
May, a parent whose kids outgrew their clothes, swaps with a neighbour in minutes.
Emma, a student, filters by price and distance to find an outfit nearby.
Kevin rents out his suits, earns points, and climbs the leaderboard.
Problem statement
How might we combine usability, sustainability incentives and social features to motivate people to buy, sell, swap and rent clothing?
Concept & differentiation
Finn.no, Tise and Facebook Marketplace all enable reuse, but none nudge sustainable behaviour or make it engaging. That gap became our opening, three ideas we leaned into:
Gamification — points and levels turn sustainable choices into something people want to keep doing.
Social features, friends, outfit inspiration and monthly challenges.
Visible impact, a CO₂-saving tracker makes reuse feel like progress.
Prototype
Low-fidelity paper wireframes tested structure cheaply, then a small design system carried through to a high-fidelity Figma prototype across five sections: Home, Wardrobe, Discover, Social and Profile.
Testing & iteration
Observational usability tests with four participants of mixed tech and sustainability backgrounds shaped real changes:
Clearer icons after users hesitated on navigation.
Richer friend profiles to support the social core.
Bigger text for readability.
Clearer Discover, adding size, availability and image sliders.
Deeper gamification with levels, challenges and a rewards page.
“The leaderboard makes me actually want to keep going.”
usability test participant
The result
The final Figma prototype connects onboarding, discovery, swapping and CO₂ tracking into one flow.
Swipe to browse the prototype →
Reflection
Motivation is a design problem. People often know the sustainable choice but don’t make it, gamification and social proof gave them a reason to keep choosing reuse.
Working as a team of three across research, ideation and prototyping taught me to align on decisions and hand off work cleanly.
Testing kept us honest. Observing real users reshaped icons, content and gamification across 21 connected screens.
I’d love to talk about research, interaction design and designing for behaviour change.