I see clearly different air temperature curves. Heated floor model is not fast enough to reach setpoint temperature during the day while keeps temperature drop rate during the night.
I think that the contained not met loads is due to the ZoneControl:Thermostat:OperativeTemperature object in the heated floor model idf. Removing it, not met hours get duplicated (being based on air temperature).
Just looking at the temperature curves I can imagine that the difference in heat consumption is proportional to the areas I've painted in red and yellow in the results for air temperature:
Regards,
Germán
--
Germán Campos