Three Yuan consists of a total of 180 years. Three Yuan is divided into Upper, Middle and Lower Yuan, each equally covers 60 years which are mapped to the chinese 60 jia-zi cycle. Each Yuan is divided into 3 Yun, so each Yun covers 20 years.
 
As per the diagram below, the year 2015 falls into the 8th Yun (start from 2004 spring day, and end on 2024 spring day) of Lower Yuan (7th-9th Yun).
 
Therefore, as per the Sam Yuan Xuan Kong Flyingstar feng shui science, any buildings which are completed construction and ready for use (move-in) within the aforesaid yun covering period, this yun number would be used as for the building life yun star along with the facing-sitting direction for calculation and setting up the water and mountain stars into a nine-palaces flyingstar (qi, energy scattering) diagram for the building.