The Houtian Bagua is also known as the "After Heaven" sequence. This sequence, although the diagram below too, is a snapshot depiction, takes into account the movement of the opposing energies of Qi (Yin and Yang) and the time (of day and seasons) involved.

You can consider that, in reality, all of the elements and energies (and their strengths) depicted in the diagram are in flux and the perfect lines drawn dividing them as you go around the compass and follow the time of day and the seasons are (like a clock's second, minute, and hour hands) blurred either clockwise or counterclockwise as time progresses and the seasons pass into the next.

Your Feng Shui consultant has the knowledge and resources to determine exactly how all of these forces are interacting inside a structure using the facing direction of the structure, the period (in time) it was built, the current period (in time), and the layout/design of the exterior and interior. He or she can also help in the design construction phase of a structure to give it an auspicious beginning and/or ensure maximization of it's potential as time progresses through it's expected life-cycle.

Hou Tian Bagua - from "Idiots Guide to Feng Shui", 3rd Edition

The basic cycle shown in the diagram above shows the seasons and time of day progressing in a clockwise direction. The actual interpretations behind this movement can be found in more advanced articles and texts.