I noticed that the Outside Temperature labels on the graph are ascending - but should be descending (at least to match the tooltips for the scatter-points).
Sorry - I don't really do PHP but would otherwise have looked for the code!
The axis is "Room minus Outside Temperature", so it should be ascending.
Left end is when outside is warm, right side when outside is cold so a large difference to inside.
This is a great screen: https://heatpumpmonitor.org/heatloss.
I noticed that the Outside Temperature labels on the graph are ascending - but should be descending (at least to match the tooltips for the scatter-points).
Sorry - I don't really do PHP but would otherwise have looked for the code!