Hi everyone, I wanted to share a project I’ve been working on to help save energy and reduce waste in my home. I’ve always been concerned about the energy consumption of my freezer, especially when the door isn’t properly closed. Leaving the freezer door slightly open can waste a significant amount of energy, and I wanted to find a way to monitor this without installing any sensors directly on the door.
After some research, I came across an innovative solution using a WiFi-controlled power switch with power measurement capabilities. I chose the Gosund SP1, which I flashed with Tasmota firmware using the Tuya-Convert tool. This setup allows me to monitor the freezer’s power usage over MQTT and trigger an alarm if the door is left open.
The system works by measuring the freezer’s duty cycle—the percentage of time the cooling engine is on. If the duty cycle exceeds a certain threshold, it indicates that the door is likely open, and an alarm is triggered. I’ve implemented this using OpenHAB rules, and it’s been working beautifully. The chart below shows how the duty cycle rises when the door is open and drops once it’s closed.
Here’s a quick overview of the implementation:
- Hardware Setup: I connected the freezer to the Gosund SP1, which provides power measurement and WiFi control.
- Firmware Update: Using Tasmota, I flashed the Gosund SP1 to enable advanced features and MQTT integration.
- OpenHAB Configuration: I set up items to receive power data and calculate the duty cycle. The rules trigger an alarm when the duty cycle exceeds a predefined threshold.
- Alarm System: The alarm is both visual and audible, ensuring I don’t miss any notifications.
This project has been a great way to reduce energy waste and keep my freezer running efficiently. I’d love to hear if anyone else has implemented similar solutions or has tips for improving this system further. Happy tinkering! 
