Normalizing to 1cu ft is left as an exercise for the interested.  Curves for
the specific heat of one cc of air at various temperatures  and RH values
exist.  So to figure out how many btus it takes to change the mass of air
one degree either way (same value) becomes a plug and play exercise.  If it
takes n BTU to raise one cc of air at 50% rh and  50f one degree f,
determined from the curve values then some multiplication to scale up to one
cubic foot will yield the number N btus required to raise that mass one
degree from 50F. A similar scaling not likely linear will allow a
calculation of the heat required to be removed or added from the thermal
mass to change it's temperature T degrees F.  QED?  No, you can't easily add
with a Post Versalog but you can do the rest to within 1 RCH or so for three
significant digits worth.  The adding will require the rest of your
significant digits.