We could also run some heat pipes through the body to improve conductivity, stretch the skin to increase the surface etc.

If the person doesn’t need to be alive to stay at a comfortable temperature we could even grind the body into a powder of tiny heat emitting particles. Then add a very fast flowing liquid with a good conductivity and our super hero heating system is good to go.

But enough psychopath talk now. I personally don’t want to turn anyone into a heating system, but I’m sure capitalism will find a way to exploit this special property. :D