Aq Monitor

Self-contained ESPHome air quality monitor for Home Assistant — CO2, temp/humidity, VOC/NOx, particulates, light, with onboard display and fan.

Internet of Things (IoT)YAMLMIT

Abstract

Aq Monitor is an open-source Internet of Things (IoT) project. Self-contained ESPHome air quality monitor for Home Assistant — CO2, temp/humidity, VOC/NOx, particulates, light, with onboard display and fan. A self-contained, Home-Assistant-integrated indoor air quality monitor. The unit watches CO₂, temperature, humidity, VOC index, NOx index, PM1.0 / PM2.5 / PM10, and ambient light, displays everything on a local OLED, exhausts air through a built-in 30 mm fan to keep the sensors fed with fresh air, and reports to Home Assistant over WiFi. It is built using YAML. The complete source code is publicly available on GitHub under the MIT License, making it a useful reference for students building an Internet of Things (IoT) mini project or final-year project.

1. Introduction

A self-contained, Home-Assistant-integrated indoor air quality monitor. The unit watches CO₂, temperature, humidity, VOC index, NOx index, PM1.0 / PM2.5 / PM10, and ambient light, displays everything on a local OLED, exhausts air through a built-in 30 mm fan to keep the sensors fed with fresh air, and reports to Home Assistant over WiFi.

I currently have nine of these running in my home and they've been working well — the design is solid and repeatable. This project documents how to build one.

2. Objective

Self-contained ESPHome air quality monitor for Home Assistant — CO2, temp/humidity, VOC/NOx, particulates, light, with onboard display and fan.

This project demonstrates how YAML can be applied to a real-world Internet of Things (IoT) problem.

4. Technology Stack

YAML

5. System Requirements

General requirements for this technology stack — check the README for exact versions.

  • See the project README for exact requirements
  • Git (to clone the repository)

6. Installation & Setup

git clone https://github.com/Verstreubulator/aq-monitor.git
cd aq-monitor
  1. Build the hardware — see docs/HARDWARE.md for the BOM and docs/ASSEMBLY.md for the build process.

Full setup instructions are in the project README.

7. Future Enhancements

Suggested extensions you can add to make this your own project.

  • Add a mobile dashboard using Blynk or Firebase
  • Store readings in a cloud database for history charts
  • Add alerts via SMS / Telegram when thresholds are crossed

8. Viva / Review Questions

Common questions examiners ask for projects in this domain.

  1. Which microcontroller / board and sensors are used and why?
  2. How does the device send data (Wi-Fi, MQTT, HTTP, Bluetooth)?
  3. Where is the sensor data stored and visualised?
  4. How is power consumption managed?
  5. How would you secure the device and its communication?

9. Source Code & License

This project is developed by Verstreubulator and published on GitHub under the MIT License. Please follow the license terms and credit the original author when you use or modify this code.

View Source on GitHubDownload ZIP

Want to build this as your internship project?

Work on an Internet of Things (IoT) project like this with mentor guidance, weekly reviews and an internship certificate from Training Trains, Erode — online or offline.

Apply for Internet of Things (IoT) Internship