Home assistant and Switchbot temperature sensor is what I use to monitor the temperature in my apartment. Simple lil dashboard to give me a visual of each temperature sensor, thermostat, and current outdoor temperatures.
I then created a template sensor to give me an average temperature of each sensor in each room to be used in an automation that controls my thermostat.
This is by far my favorite automation cause I not only use the average temperature in my home sensor, but I also use outdoor temperature, and the season integration home assistant has to help control my thermostat throughout the year without me having to adjust it for the different seasons.
This is also tied to my laundry automation and cooking automation to help reduce the pain on my bills. I’m still working on this automation because winter hasn’t fully hit us here yet in Wisconsin, so I’m still collecting data as the weeks pass by.
So my idea is that by next year, when spring comes around, this will be a flawless automation that will run without me worrying about wasting unnecessary energy when the thermostat is on.
You basically just created your automation. Now, all you need is home assistant, an energy monitoring plug, and your smart speaker (Alexa, Google,or both) and put your requirements into an automation. I’m willing to help you build this automation if you get stuck.