That's not really how thermodynamics work. Heat is heat. If it's in an insulated box, ie fridge, the total heat of the system is the same wherever it is located. It might not be brilliant for bringing a cold bucket of wort up to temperature, but it will quickly bring the ambient temperature to a level, which is what a temperature controlled chamber is.
Or to think of it another way, it can easily keep the whole bucket of wort at a temperature, so keeping a fridge full of air warm is child's play.
If it's not possible to set the thermostat very high it wouldn't be very quick heating the wort, but then how often would you want to do that? In general most temperature rises can be maintained by the free rise thermal output of the yeast