I have been modeling a Building and I would like to know the considerations that I have to take account regard to the ceiling void 0.5m high. I am Considering this ceiling void as a space. The reason for that is because from about 0.2 m of high, we start to observe convection effects, and I think, Considering that ceiling only as air gap (convection effects are not being taken into account), I am not modeling that appropriately. So, which of two considerations above is the better one? Thanks.