[Bldg-sim] Internal Mass Issues with Solar Distribution Model

[Samuelson, Holly Wasilowski]

Dear Bldg Sim,
I am trying to understand how the internal thermal mass (aka "InternalMass") is being handled in my EnergyPlus models. On page 222 of the EnergyPlus Input-Output Reference it states, "simplifying calculations using internal mass must be used with caution when the "FullInteriorAndExterior" Solar Distribution model is chosen. 

Could anyone kindly help me understand what that means?  Does that mean that my internal thermal mass does not "see" the solar radiation potentially hitting it (which might realistically be the case for certain interior elements if they are always in shade)?  However, would you assume that this internal mass is still exposed to the indoor air, and thus could still be absorbing or emitting heat in that way?

Many thanks for any guidance.
Best,
Holly

Holly W. Samuelson, DDes, LEED, AIA 
Assistant Professor Harvard Graduate School of Design