I heat my 24x24 with radiant electric, 240v, 3000 watt tube, 60 degree all winter, less than $300. Two years ago it was $273 for the season. last season $296. Of course it is on a dual meter system at $.045 per kwh. 3 1/2 inch walls, 3/4 foam under the floor(for summer sweating), and lots of...