Build a Smart HVAC Energy Saver with Arduino, PIR & CO2 Sensors

Every part needed, pre-tested for compatibility, with an AI build companion trained on this exact project. Shipped from Bengaluru in 3-5 days.

Every day, classrooms, labs, and hostel rooms run air conditioners while empty, wasting thousands of rupees in electricity. With this kit, you build a prototype that reads PIR motion and CO₂ concentration through an Arduino to determine if a space is genuinely occupied. If the room stays empty for 15 minutes, a relay cuts HVAC power; when someone returns, the system automatically restores it — no manual intervention needed.

What You'll Build

You’ll assemble a breadboard-based controller centred on the Arduino Uno R3. An HC-SR501 PIR sensor catches movement, while the MH-Z19B CO₂ sensor tracks occupancy even when people are still. The DS3231 real-time clock enforces the 15‑minute vacancy delay, and the OLED displays live sensor data and relay status. The entire circuit uses decoupling capacitors and flyback diodes for clean, reliable switching — a complete, self-contained logic block ready to integrate with a real HVAC cut-off line.

What You'll Learn

• Reading PIR sensor interrupts and debouncing motion signals to prevent false triggers
• Interfacing an MH-Z19B CO₂ sensor over UART and converting ppm readings to occupancy thresholds
• Using a DS3231 RTC to schedule precise 15‑minute vacancy delays before relay action
• Controlling a relay safely with flyback diodes and driving an I²C OLED display

Kit Contents

Why Buy This Kit Instead of Sourcing Parts Separately

Who This Kit Is For

Ideal for CBSE Class 11–12 students building physics or computer science projects on energy conservation, B.Tech ECE/EEE students prototyping for Smart India Hackathon, and ATL Tinkering Lab mentors demonstrating real-world IoT automation. If you’ve made an LED blink with Arduino and want a tangible challenge that saves actual electricity, this intermediate kit connects classroom sensors to a practical home‑energy problem.

Built and Backed by Compoden

Every Compoden kit ships with an AI build companion trained on this exact project — accessible via a QR code on the box, with WhatsApp and email backup. We've spent 10 years building projects for makers, schools, and institutions across India. If a part fails because of a manufacturing defect, replace it free within 7 days.