Underfloor heating systems are controlled through a relay (on/off) signal. The relay is being activated with a varying duration when heat is requested. At a high heat request level or high intensity heating, the relay is closed for a longer time than for a low heat request level or low intensity heating.
This is data is summarised as Consumption data in the app and displayed in the graph. Consumption is calculated from how much time the relay has been activated multiplied by how much electrical power has been applied to the heating system.
Themo has built in capabilities to estimate the power level of your underfloor heating system.