Google says there are 171K English words. And I’m guessing they are not counting W as a noun… so where’s the rest of the words?

Not taking away from your effort but I am in the camp that this visual makes little sense.

The main reason is you are not controlling for the possible change in outdoor temps during the period your one sensor was in the uninsulated room.

The temperature monitor you mention is fairly expensive. You should look at the Govee products, which are about $15 per sensor.

Another option (though still susceptible to external temperature changes) use one sensor for 30 days in each room and separately get external weather data for each of those 60 days, and plot the difference between internal and external temperature in each room (x-axis wouldn’t be a date but instead day 1 to day 30). Just a thought.

I know several COUPLES that make that much but for an individual could be tech, business owner, big lawyer, specialized doctor. Lots of options