I wanted to do this project because is a good starting point for home automation.
My idea is to use the nice ESP8266 and do everything in python (micropython).
I bought a Nodemcu ESP8266 a while ago and I wasn't using it, so when I heard about the micropython project, I got interested. I flashed the ESP12 with the latest micropython for ESP8266 and starting to play.
I find MQTT as the perfect solution for a project involving IoT and Home Automation, so that's what I was planning to use. As far as I know, nobody has done exactly this thing using micropython (you can find similar things using LUA or C) and adding a OLED 128x64 screen seemed like the right thing to do in a thermostat.
I think a thermostat is one of the most complicated things in home automation out there, so once ready it can be easily scaled to other parts of the home like appliances, lights, shaders, etc. that will be far more easy to automate.
You may be interested in these two home automation projects. One is replacing a waterbed thermostat that failed. The other modifies the thermostat for a gas furnace and also only turns on the hot water tank at low cost time of use in order to save $500+/year. Two of many NodeMCU projects. All are documented here:https://sites.google.com/site/nodemcu12e/