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CIID · Tangible User Interfaces · 2025

Temp Mediator

Linked thermostats that help flatmates settle on one temperature everyone can live with.

  • Tangible interfaces
  • ESP32
  • Hardware
A hand moving a fader on one of three white thermostats lit with coloured LEDs.

Watch on Vimeo

The short version

About 1 minute

Situation
The brief was to design a product that builds community, for an imaginary client, IKEA.
Problem
Flatmates disagree about room temperature, usually silently. Research showed that thermostat disputes, unlike most roommate conflicts, are measurable, which makes them something technology can help with.
What made it hard
  • Several devices had to talk to each other without depending on home Wi-Fi.
  • The system had to be fair, and visibly so, or people wouldn't trust it.
My role

A two-person project with Dishank Gandhi. I did some of the coding, 3D printed the enclosures, ran user testing and made the video.

With Dishank Gandhi

Tools: ESP32, ESP-NOW, custom PCBs, 3D printing

Key decisions
  • Each room gets its own fader, modelled on DJ console controls, so it needs no explanation.
  • The devices form their own low-power wireless mesh over ESP-NOW and agree on a temperature through a weighted average.
  • Haptic resistance in the fader physically shows where the group's consensus lies.
Outcome
A working set of connected devices, built with four custom PCBs and 3D-printed parts. Testing showed that seeing other people's preferences makes people moderate their own.
More about the project CIID project page

Details

Each device sits in a room. Moving its fader sends the change across the network in real time, and every device recalculates a temperature that balances everyone’s preference.

Four thermostats side by side: three lit with coloured LEDs showing each fader position, and a plain white one

Building it

The four devices opened up to show their custom circuit boards, wiring and faders, with 9V batteries
An early laser-cut wooden prototype with three fader slots
Two people building circuits at a table covered with wires, sketches and laptops A teammate holding a set of faders over a breadboard full of wires while another watches the laptop
A teammate trying a cardboard fader mock-up beside the working electronics

What we learned

  • Transparent algorithms build trust and make people more willing to use the system.
  • Seeing others’ needs changes behaviour: people moderated their preferences.
  • Hardware is hard. Building four custom PCBs and 3D-printed enclosures gave us new respect for consumer electronics.
  • People adjust their preferences less often than we expected.
  • Testing surfaced feature ideas such as a vacation mode for absent flatmates and a simple off switch.