Vastu is a Science based on Climatology and has very little to do with religion and spirituality. It's an ancient science that guides the people to construct their Homes, Offices, Shops, Industries in a better way that helps in healthy living and create overall prosperity.
Vaastu considered the interplay of various forces of nature involving the five elements of earth, water, wind, fire and ether and strives to maintain equilibrium as these elements influence, guide and change the living styles of not only human beings but every living being on earth.
Vastu Shastra unifies the science, art, astronomy, and astrology, it can also be said as an ancient mystic science for designing and building. Vastu Shastra helps us to make our lives better and will secure from things going wrong.
Vastu can be used for every structure like room, house, temple, shop industry, town planning, tour, cities and even for land. Vastu can be used for micro as well as for macro level. Every creature on earth starts its life with sunrise as it performs day & night. Hence there is much importance of the sun in everyone life. It gives ultraviolet rays in the morning and infrared rays in the evening which one is the basic need to reduce/generate bio-chemical germs, N2/ Oxygen / CO2 on earth.
Sun indicates light (illumination) will power, generosity, solar system, luck or fate, mobility and in the body. It rules over bone, eye, heart, spinal cord, blood circulation, and soul, etc. Hence east direction is auspicious; it belongs to Lord Indra. North is considered auspicious since magnetic lines of forced moves from North to South, thus the origin of all the life.