First off, they looked into a plug-in thermostat controller, and found a cheap one called the HeaterMate. Unfortunately it left a lot to be desired.

Four engineers from Spark have pooled their skills and resources to create a new open source smart thermostat based on Arduino using $70 of components.

This project bears some resemblance to this Arduino-controlled AC, but it seems more hackish to us. And that’s a good thing – hackers have to keep cool somehow.