hi my house is about 1979 built, and has cavity walls, which are filled with insulation. The downstairs toilet is always very cold. It has 2 out side walls, one to the front and the longer one to the side. The rear, where the toilet is mounted is internal and the door side is internal. It has a little window in it as well. The rest of the house heats up ok, but this does not. We have warm air heating so no rad in here, but we leave the door open to warm it, but it dont do much good. Any ideas please?