A plan can be redrawn until the week the slab is poured. A window can be moved, a wall thickened, a stair turned. But the direction a building faces is settled the moment it is sited, and every hour of its remaining life is spent answering for that one decision.
The hour that tests the drawing
We have come to test our plans against four in the afternoon rather than noon. Noon is generous: light falls from above and flatters almost any arrangement of rooms. Four is unforgiving. The sun is low enough to reach deep into a plan, and it exposes every surface that was detailed without being imagined.
This is not a rendering exercise. A model under a single lamp, tipped to the right angle, will tell you more in ten minutes than a week of simulation. What you are looking for is not brightness but the length and the edge of the shadows, because those are what a person actually reads as depth.
Three questions
We ask the same three things of every room. Where does the light enter. What does it land on first. And what, at four in the afternoon, does it refuse to reach. The third question is usually the one that changes the drawing.
A building that has answered these honestly does not need to be explained to the people who use it. They will feel, without being able to say why, that the rooms arrive in the right order.