Concentrate on a specific area on space

[basboy]

Hi, just a simple question on CFD. I want to concentrate on a specific area of the whole model and use a finer grid there. But this area is a part of a room. Is there way to do that? I can't just make the overall grid finer because it exceeds the million limit and I also cannot create a multi-space containing the rooms I want cause then there is a flow imbalance.

Thanks