Temperature change is a measure of energy lost from the body. Measuring radiation, sensible and evaporative convective heat loss to the atmosphere would just tell you the mechanisms, and would not change the total heat loss.

These studies are based on the energy conservation principle, so that

Net radiation + Sensible convection + evaporative convection + metabolic heat production + change in heat storage = 0.

Change in body temperature, multiplied by body mass and specific heat, give you a change in body heat storage.