It's cheap but what's the 0power consumption? This tutorial from Eric Tsai covers a similar architecture but a lot more extensible, with a lot more explanation, and each end node can be powered from a coin cell for many years:
ESP-12f module running with tasmota firmware consumes around 30mA when measured on the 5V side, if you want to go further down, deep-sleep option of ESP8266 is the way to go, but tasmota firmware doesnt support deep-sleep(may be you need node-mcu firmware to achieve sub-mA consumption). There are CR-123 3v battery powered ESP8266 temperature/humidity products which use deep-sleep mode and report the sensor samples every hour so that devices operates atleast a year on battery power(check out shelly H&T product)
https://www.hackster.io/erictsai/lora-tooth-small-ble-sensor...