If flights were conducted with the recirc fans off during cruise, how much would this increase fuel burn
That's an interesting question, because where I work this issue had never come up; in fact, passenger comfort is not ever curtailed in the interest of saving fuel. For that matter, we also run the APU [400-800kgs/hr] and 2 packs at the gate long before passengers board, to ensure proper conditioned cabin air. And besides pax comfort, I'm among those crewmembers who like lots of fresh, conditioned air. In flight and on the ground.
