^^ basically yes, real world efficiency this isnt a feasible thing. I'm obviously not against innovation and ideas stemming from a lab environment but its not a competitive solution
There's a reason why heat sinks are mounted on thermal compounds so that there's no air between them and the hot surface. You can use other things if you run out of your compound, one of them is ould, but oil, as a temporary solution. Putting people in water or oil baths would greatly increase efficiency.
The matrix solution, so would seem to nullify the main utility of a human being for what is quite a low heat output. Its going to be more realistic to treat cattle in this way perhaps. I love the matrix story especially the first movie :p but movies so often skip super obvious questions and just plain cattle put out so much more heat and energy then humans; I believe we waste a ton of energy on that useless brain thing other creatures are likely superior return on investment to people.
I believe they recover heat from a farm barn of hens for example but never individual creatures that I've ever heard of.
The way I see this being feasible at some time in future is the body suit for devices built in that somehow captures heat and then recharges a low power mobile phone. I guess this is feasible, even with some skin contact you can easily remove it conveniently.
I'd still think the kinetic energy of a person moving about is superior to heat capture and restricting movement is not going to be acceptable really