Talking about the cost is really a secondary thing, the primary focus should be on the actual amount of energy (kWh) being consumed to heat your house (charge rates vary considerably). Also, the question is whether you have intermittent heating or continuous heating - comparing continuous heating with national statistics where intermittent heating is the norm will always lead to frustration, your temperature levels are quite possibly different from what the statistics are based on (low levels of average heating in the UK). Finally, how well the house retains the heat is of enormous importance. Underfloor heating through wooden floors is somewhat inefficient (certainly less efficient than, say, with tiled floors) as wood is a mild form of insulation and your heating elements are to a degree insulated from the air above the floors (assuming heaters are below the surface material).