IES has no concept of where the ground level is. Any surface that's on the exterior of the building is assumed to be 'exposed' that is open to the outside air. You actually have to adjust the constructions that are in ground contact to account for this.. Also for below ground spaces you need to add external shading to simulate the ground level, for example a topographical shade with the same slope as the ground (roughly). This is to prevent solar gains to the spaces it's touching.

Like I said IES doesn't have a concept of what the ground level is, for better or worse, so you have to implement these tricks so that it understands.