I wouldn't be so quick to think there is a fundamental difference in the statements I am making and what Guamaque is making, there is a total energy budget involved in cooking a piece of meat, in part, the rendering of the collagen, necessary for a tender brisket or butt, is what I am focusing on. However, if you consider that the phase shift, from solid to liquid, if the collagen use energy in two different ways, you end up with the consideration that some of that energy is released as measurable heat (evaporative or conductive loss or gain), some as retained heat (meat temperature loss or gain) and energy expended to shift the stasis of molecules from one phase to another (measured only by calculating the other aspects). Hence, not a simple equation, as the variables in a given piece of meat are not a known entity.
The reason foil wrapping increases cooking speed is not related to it's retarding evaporation, thus preventing evaporative cooling, it is related to the effective rise in temperature effected by trapping a super heated gas (steam) in direct contact with the meat. There is also a potential gain in pressure, although the amount developed is, I suspect negligable. The steam acts much more efficiently than dry air in accomplsihing thermal transfer of it's heat to the meat than dry air, due to the increased density it possesses and the nature of how thermal transfer of energy works. If you use steam in an closed environment to cook meat, it is, quite possible to dry out a piece of meat while cooking it in a very moist environement. The steam will still remove the moisture and it will evacuate the meat as soon as you change the vessel holding the steam next to the meat to an open environment. Witness the fact that it is possible to have very wet, yet stringy, dry, pot roast.
Whip It Off, Chambers!
"perhaps...but then again...maybe not..."