The idea of this project is to use an LDR light sensor and a DHT11 temperature sensor to automatically turn the fan on when someone is occupying a room and if the temperature is above a certain threshold.
That means, when someone enters a room and turn the lights on, the first condition is that the light sensor senses this, and if the temperature is above the given threshold, the fan starts automatically.
The speed of the fan is mapped to the temperature. The hotter it is, the faster the fan will turn.

Moreover, it also includes a potentiometer just in case when someone is not comfortable with the automatic speed of the fan and they want to control this manually.
When the potentiometer is activated to manually control the speed of the fan, it disables the previous automatic fan system and the user controls the speed manually as they please.
Once the potentiometer is set back to 0, the previous function kicks back in, and the light sensor and the temperature sensor become the main informants if the automatic fan system should run and to what speed, or not.

Meanwhile, the LCD screen shows the temperature of the room and the speeds of the fan in automatic mode and in manual mode.

Bill of Materials

1x Arduino Uno
1x Breadboard

1x DHT11 sensor
1x LDR Light Sensor
1x Resistor
1x Potentiometer

1x LCD 16×2
1x I2C LCD backpack
1x LED Blue
1x LED Green
2x Resistors
1x DC Motor
1x Transistor
1x Diode


Circuit Diagram





Prototype Performance



Automated Fan System is a project of IAAC, Institute for Advanced Architecture of Catalonia developed at Master in Advanced Architecture in 2021 by Student: Yerwant Megurditchian and faculty: Cristian Rizzutti, and assistant: Arman Najari.