Birthplace-Centered Houses
The Koch house system (also called Birthplace system) was developed by Walter Koch in the 1960s and became popular in Germany and among German-influenced astrologers. Like Placidus, Koch uses a time-based semi-arc division, but grounds the calculation specifically in the latitude of the birthplace. Koch tends to produce cusps close to but not identical with Placidus, with differences most visible at extreme latitudes. It shares Placidus's breakdown at high latitudes.
Koch vs Placidus
| Feature | Koch | Placidus |
|---|---|---|
| Basis | Birthplace semi-arc | Planet semi-arc |
| Cusp differences | Usually minor vs Placidus | — |
| Polar latitude issues | Yes — same as Placidus | Yes |
| Popularity | Strong in Germany | Global default |
When to Use Koch
Koch is most useful as a secondary check on Placidus: if a planet falls in a different house under Koch than Placidus, test which interpretation rings truer through life events. Koch is popular among astrologers who work with astro-locality and want grounding in the specific geographical context of the birth. For most interpretive purposes, Koch and Placidus produce similar results — any planet near a house cusp in Placidus is worth checking under Koch to clarify its house placement.