Flying Star Feng Shui, also known as Xuan Kong Fei Sing, is a formula based Feng Shui method that takes into account the year the property was built and the facing direction of the property. This method takes into consideration the time element. It is believed that the property, when it was built, has contained in it certain type of energy. The goal of Flying Star Feng Shui is to interpret how the energy interacts and how it influences people who occupy the property.
Using the two information points mentioned, a Feng Shui practitioners will be able to chart what is consider the Natal Energy Chart of the property. The chart is consist of a series of numbers. Each number has is associated meaning. The objective is to interpret the interaction of "stars." They use the word "stars" to mean numbers, it does not mean stars in the astrological sense. The Chinese just like to use fancy word like "star" instead of just number.
In Feng Shui, form, meaning the landform and internal physical design and layout, affects the stars. There are good stars, such as numbers 1, 6, 8, and there are bad stars, such as number 2, 3, 5, 7. The skill level of a Feng Shui practitioner is to interpret what has happened and what could happen, based on how the stars interact with one another and how the landform and internal design of the property will "trigger" or "activate" a certain star.
It is similar to an astrological birth chart for a person, but instead it is a Birth Chart for a structure instead.
Best of luck.