Earth, was formed crores of years ago, it was a ball of fire. In due course of time, the rocks melted and the surface has acquired magnetism due to the embedded matter within. It acts as a magnet with North and South-pole.
Sky comprises of vast space in the universe.
Air or the atmosphere comprises of gases like oxygen, nitrogen, carbon dioxide, inert gases etc. The very basis of life on earth is because of oxygen in the atmosphere.
Water is comprised from the rainfall, which is brought from the clouds, comprises of the major part of earth and is a mystifying fact of nature.
Sun is the most important in Vaastu Shastra. It imparts solar energy and is the vital source of life and is worshipped as an incarnation of God.
Vaastu Shastra gives a complete insight and understanding into the various fields related to house-direction, topography, soil, geography, environment, physics and orientation of the building, in relation to the plot, soil, surroundings and the personality of the owner / dweller. There is no room for rituals and superstitions.
Vastu orientates, places and dictates the proportions of every detail as in building lines, skylines, elongations, levels, slopes, water tanks (underground and overhead), kitchen, bedrooms, toilets, staircase, heights of ceilings and roofs, entrances and loci of doors and windows, compound walls and so on.

Vaastu Purush Mandala signifies metaphysical plan of a building.
Vaastu means: a surrounding, environment, matter or nature.
Purush means: energy, work power, vigor or soul.
Mandala means: the astrological chart-which relates the layout to the orientation.

According to the traditional Indian Cosmology the surface of earth is regarded as decarnated by sunrise and sunset, by East and West, and also by North and South points, and is represented by a diagram or mandal of a square. The essential and basic form of Vaastu Purush Mandala is a square, and is symbolic of square Mandala of earth and the ecliptic. It symbolizes recurring cycles of time. The Vaastu is dependent of lunar and solar cycles.

The name Vaastu derived from Vaastu meaning, matter. The image of Vaastu Purush, one with Mandala is drawn in the likeness of man. His head lies in the north east in the Mandala of 64 squares, the legs in the south west, right hand in north west, left hand in south east and other parts of the body fill the square. The body of Vaastu Purush comprises of 45 Gods and deities.