my workshop is either the kitchen table (21 degrees C) or the conservatory which has the benches and tools, (5 degrees C) no heating, but it acts as an insulation barrier for the house, absorbing all the heat thrown out from the walls, the house, well since we had the cavity walls done the whole house is heated from a single radiator in the downstairs toilet, maybe 2 foot square, set to 2 , and that keeps it a comfy 21 degrees downstairs. upstairs there is the heated towel rail, plus the hot water pipes to the boiler under the floor. which keeps that a comfortable 19-20 degrees. the only problem is in the summer when the conservatory can top out over 40 degrees.