Netherlands-based Electronics hacker Elco Jacobs designed the UberFridge as temperatures in his city are hot enough to ruin batches of homebrew. By adding two temperature sensors (one for the beer, one for the fridge) to a Arduino Nano that controls the climate with an algorithm designed by Jacobs. Current data can be found on an LED display on the fridge or from a webapp that gets information from a USB connection going from the Arduino to a DD-WRT linux-enabled wireless router.
If you’re serious about your beercraft, this should be a great weekend project. The ideal fermentation temperature for most beers is 18°C and unless you have a basement it may be hard to find those temperatures during the summer unless you go crazy with your air conditioning. Full schematics of the build, tutorials on how to link the various systems, and the open source code for the UberFridge webapp can all be found at the source link below.