2 Ways,

1. Either use the proper electrical heating system and get it wired in on a theomostat, expense depends on how often its on and the wattage of the heating elements but you can have it come on automatically depending on the tempreture.

2. Do what ive seen more and more people doing now and thats running the system off the cetral heating system, small diamiter plasic pipe round the floor linked to the central heating system. Its cheap but its not indepent as with electrical elements because its linked to the radiators.