My name is Fred and I'm from France. (In advance, sorry for my English).
I did an ESP8266 project in aim to make my home smarter.
Like I say in subject, my object is a T/H sensor on battery alimentation which communicate in WiFi (Normal it's an ESP8266).
Like everybody knows, WiFi and consumption is not a good melt. To resolve this problem, i used a TPL5110 from TI.
Thanks to this Timer, the sensor can operate during minimum 1 year with uplink all of 1 hour.
My other goal was to do an end design object which I can put in my home.
Finally my challenge was to spend less than 10$ !
http://faire-ca-soi-meme.fr/domotique/2017/01/20/capteur-temperature-humidite-wifi-sur-pile-a-moins-de-10-euros-hardware/
If you have questions, I can help...