If the design and installation of your hydronic floor heating is poor, then your floor heating system will cost many times more to run compared to your aircon heating.
If designed and installed correctly, and depending on your energy source (e.g. gas boiler or heat pump), a hydronic floor heating system will cost either the same amount to run as reverse cycle aircon (basic hydronic system), or up to 40% less (best hydronic system).
This is mainly due to the fact that with aircon, you suffer from air stratification (meaning the warm air rises to the ceiling, whilst cold air stays down below), and you are relying on the warm air touching your skin to warm you up (whereas with floor heating, your body is being warmed by radiation emitted from the floor, which is a much more effective mode of energy transfer).
