Koch Houses

Definition

Koch is one of the ways of dividing a chart into twelve houses — a "house system." It was introduced in Germany by Walter Koch after World War II and is also called the Birthplace System (Geburtsort-Häusersystem). It takes the path the rising degree travels above and below the horizon, splits each of those two arcs into equal thirds, and uses those marks to build the in-between house cusps. Like the Placidus and Regiomontanus systems, it gives houses of unequal size, and like them it breaks down at extreme latitudes, where that arc can no longer be divided.

In Tradition

Among modern Western astrologers, Koch is one of the main twentieth-century alternatives to Placidus. What sets it apart is its claim to use your actual birthplace latitude consistently for every cusp, not just for the angles. Surveys of practice show Placidus as the majority choice, with Koch and equal houses the most common alternatives people switch to. Koch is especially common among German-speaking astrologers and those who follow them.

In Practice

To build the in-between cusps — the 11th, 12th, 2nd, and 3rd — a Koch chart takes the time the rising degree needs to climb from the eastern horizon up to the meridian overhead, splits that span into equal parts, and projects those time-divisions back onto the zodiac. The cusps that result can sit noticeably differently from Placidus, especially the further you go from the equator. Koch is built into most modern astrology software and is the default in some German-language programs. Above roughly 66 degrees of latitude — the Arctic Circle — the system breaks down, because the day-arc itself vanishes; whole signs, equal houses, or Porphyry are normally used instead at those extremes.

Historical Origin

Holden records the Koch Birthplace System as a post-WWII German introduction, with Koch promoting it as the system that uses the birthplace latitude for all of its cusps. Holden places it among the twentieth-century contenders for house division alongside Equal House, Campanus, Topocentric, Regiomontanus, and the majority-used Placidus, noting that some astrologers moved away from Placidus to Koch or Equal House.

Further Reading

  • James H. Holden, A History of Horoscopic Astrology
  • Deborah Houlding, The Houses: Temples of the Sky
  • Robert Hand, Whole Sign Houses