Classroom CO2 and Ventilation Monitor Network with a Raspberry Pi Gateway for Schools

The problem: nobody can see stale air

Many classrooms, coaching centres and lecture halls are crowded, and windows stay closed because of heat, noise, dust or cold. Carbon dioxide (CO2) builds up as people breathe, and it is a practical indicator of how well a room is ventilated: when CO2 is high, the air in the room has not been refreshed. Teachers cannot see this, so rooms can stay poorly ventilated for whole days.

The UK government's guidance on ventilation and air quality in education settings gives simple bands: under 800 ppm means ventilation is good, 800 to 1500 ppm is adequate, and over 1500 ppm means ventilation is poor. The same guidance explains that between 2021 and 2023 the Department for Education delivered CO2 monitors to all state-funded education and care settings in England, and gives advice on placing them, such as at seated head height, away from doors, windows and vents, and at least half a metre from people. Most schools elsewhere have no monitors at all.

What already exists and the gap

• Standalone CO2 monitors such as the Aranet4 use an NDIR sensor, show readings on an e-ink display and sync over Bluetooth to a phone app. They are accurate, but each is a separate device, and a school needs one per room plus someone to check them.
• Commercial building management systems monitor air quality across large buildings, but they are designed and priced for offices and new buildings, not existing schools.
• Cheap "air quality" modules based on metal-oxide gas sensors report an "eCO2" value estimated from other gases rather than measuring CO2 itself, so they can be badly wrong.

The gap is a low-cost network built for schools: a true CO2 sensor in every room, a clear signal for the teacher, and one dashboard and weekly report for the school, running locally so it works even where internet is unreliable.

Inspiration

The UK Department for Education's monitor rollout showed that a simple, room-level signal changes behaviour, and its guidance gives you tested thresholds and placement rules to build on. Your project turns that idea into a connected system with history and reporting.

What you build

• Sensor nodes: a Raspberry Pi Pico W or ESP32 with a CO2 sensor that measures CO2 directly (NDIR or photoacoustic, such as the Sensirion SCD40 or SCD41), plus temperature and humidity, and a traffic-light LED or small display.
• Gateway: a Raspberry Pi on the school network running Mosquitto, a Python service that validates and stores readings, and a local dashboard. Everything runs as systemd services and restarts after power cuts.
• Dashboard and reports: live room tiles in green, amber and red, charts, last seen times, and a weekly report per room for school leaders.

The technically interesting part

• Measuring correctly. CO2 sensors need warm-up, automatic or forced calibration, and careful placement. You will compare every node with a reference monitor and document the error.
• A gateway that survives a school. Power cuts, SD card wear and no internet are normal. You will design for restart, log to a reliable database, and possibly boot from more durable storage.
• MQTT design. A clear topic scheme per school, room and node, retained status messages and a Last Will so the dashboard knows when a node is offline.
• Useful reporting. Turning thousands of readings into three insights a head teacher will act on is the real product skill.

Deliverables and how to evaluate it

Measure node accuracy against a reference monitor, message loss over two weeks, gateway uptime across deliberate power cuts, and dashboard load time. Report how much time each room spent in each band, and collect teacher feedback on whether the indicator changed what they did.

Stretch goals

Estimate air change rates from CO2 decay after lessons, link readings with the timetable, add optional cloud sync for school groups, or build battery-powered nodes with deep sleep.

Path to a product

Schools, colleges, coaching centres and private school chains care about student comfort and health, and parents increasingly ask about air quality. A product version would bundle a gateway and nodes as a kit, a simple installation guide, a school-group dashboard and termly reports. Start by running a pilot in a school you can reach and asking which report the principal would actually read.

Want feedback on your scope before you start? Discuss this idea at /account/fyp-ideas/classroom-co2-and-ventilation-monitor-network-with-raspberry-pi-gateway/, ask a specific question at /account/ask/, or book a session at /account/book/. New to Sefism? Create a free account.

Learn what you need on Sefism

• Embedded systems and IoT roadmap: pick the Raspberry Pi option for GPIO, services, MQTT and dashboards.
• Embedded systems and IoT cheat sheet: MQTT topics, Last Will, systemd services and alerts with hysteresis.
• Raspberry Pi Documentation for setup, interfaces and power.
• Eclipse Mosquitto and MQTT Essentials for the broker and protocol.
• Node-RED for a quick dashboard on the gateway.