Xuan Kong Da Gua (玄空大卦) reads a property rather than its occupants: it names the orientation as an I Ching hexagram and its exact inverse, and judges the elemental relationship between the two. Where Ba Zhai asks which directions suit a person, an XKDG audit asks what the structure is doing with its own axis — a different question, answered without any birth data at all.
What an XKDG property audit produces
An XKDG audit identifies four hexagrams for any property: the sitting hexagram (the hexagram of the back wall direction), the facing hexagram (the hexagram of the front), and the bedroom + work-desk hexagrams within the structure. Each hexagram is read against the occupants' birth-year hexagrams for compatibility. A property whose sitting hexagram clashes with the breadwinner's birth hexagram is fightable; a deeply harmonious match is rare and worth seeking out before purchase.
From compass bearing to hexagram
A compass reading of the back wall (sitting direction) is taken with a Lou Pan (Chinese geomantic compass) or a calibrated Western compass with magnetic-north correction. That bearing is placed on the 24 Mountains, each mountain belongs to one of the eight trigrams, and the sitting and facing trigrams are stacked to give a hexagram and its exact inverse. Because three mountains share each trigram, the reading here resolves to eight orientations of 45°, changing over at 22.5°, 67.5° and every 45° from there. Classical practice subdivides the ring more finely and reads the result against the current Period (Period 9, 2024–2043); neither the finer subdivision nor the Period is computed in this app.
Reading hexagrams against occupants
Each occupant has their own birth-year hexagram. The sitting hexagram is compared to it through three levels: (1) trigram compatibility (upper trigram of one hexagram against lower trigram of the other), (2) elemental relationship (the five-element interaction between the two hexagrams), and (3) "host-guest" dynamics (which hexagram dominates). Strong matches: the sitting hexagram supports the occupant's birth hexagram. Strong mismatches: the sitting hexagram drains or controls the occupant. Most properties are mixed — some occupants benefit, others struggle.