I have a heater in the greenhouse. For a while the greenhouse was bubble-wrapped but I the graphs didn’t noticeably twitch. And I hated the bubblewrap. So it’s gone.
The temperature data is from a BME280 sensor hooked up to the raspberry pi with a bit of shell scripting and gnuplot mixed in. The spikiness of the graphs is due to the heater. I’m not sure of the accuracy, and gnuplot smooths out the occasional mystifying spikes. Here’s the most recent raw data if you’re interested. If you click on any of the graphs below it should update in something approximating to real time.