In this video, I'll be covering a trick for the creation of a smooth face in a building that may not necessarily need to be 100% smooth. This may be a quite common case, so I decided to post this trick.
You can start by a 1x1x1 box, and then crease all the subobjects. Remember that in order to do so, you need to click Ctrl while making a window for the selection of the whole model. Instead of selecting the model, you will be selecting subobjects according to the filter you have at that moment. The value of creasing should be infinite for this operation.
Now we need to apply smoothness to the object. But wait! Everything is creased, so nothing happens. Exactly. Everything will make sense after the next step.
Refining a mesh would create a face per each face in the subdivision... that's a lot of faces if you're on level 3. But you can also refine by selection. That means that the only face which will get more complexity is the one selected.
As soon as we start editing, we'll notice that the front face acquires smoothness, and can be easily edited into the shape you want. The reason for this to happen is that the new faces created in the refinement don't have creasing assigned, so they are free to move and be edited smoothly.
As usual, you can follow the link and see the video in HD.