Vastu Shastra works on three principles of design that cover the entire premise. The first one is Bhogadya, which says that the designed premise must be useful and lend itself to easy application. The second is Sukha Darsha, in which the designed premise must be aesthetically pleasing. The proportions of the spaces and the material used, in the interiors and exteriors of the building - ornamentation, colour, sizes of the windows, doors and the rooms and the rhythms of projection and depressions - should be beautiful. The third principle is Ramya, where the designed premise should evoke a feeling of well being in the user.
Also, Vastu Shastra is a complicated form of science put together by seventeen sages. There are certain rules that should be followed while building a house or a building. For instance, the building's underground water tank or well should be situated in the northeast direction. But, if the building has an overhead tank then it should be placed in the southwest direction. Also, more space should be left to the north and the east of the building compound and less on the south and the west. Open space should be kept around the building and if the plot has a road on the east-north directions, it is better for the inhabitants.
Vaastu Shastra (Vaastu- physical environment and Shastra- knowledge) is one of the traditional Hindu canons of town planning and architecture. These canons are codified in texts such as Manasara Silpa Shastra (by Manasara), Mayamatam (by Maya), Viswakarma Vaastushastra (by Viswakarma), Samarangana Sutradara (by Raja Bhoja), Aparajita Praccha (by Viswakarma's son Aparajita) and Silparatna. Other treatises such as Agni Purana and works by Kautilya and Sukracharya are not popular even though they preceded the previously mentioned documents. Distinction of style exists due to each documents place of origin. Mayamata and Mansara Silpa Shastra are considered Dravidian because they are from south India whereas Viswaskarama Vaastu Shastra is considered Aryan due to its north Indian origin. Vaastu Shastra deals with various aspects of designing and building living environments that are in harmony with the physical and metaphysical forces/energies of the cosmos such as the gravitational, electromagnetic and supernatural. Building practices based on limited interpretations of these principles are still sustained in specific areas of India.
Vaastu believes that there are essentially two types of forces, which are equal and opposite in nature. The interaction of these two forces is cosmic ordained and produces a third type of force, which is called ‘bioforce’ or ‘PRANA’, needed for life to exist. One type of force is subtle and fine. The other is dark and dense. We can , for sake of understanding this subject, call the first one as 'positive' and the other as 'negative'. 'prana' is liberated by the interaction of these forces. Over the surface of the globe these forces continuously interact releasing bio-energy. When a structure is built over the surface of the earth it comes in the way of a natural interaction. Both the forces enter the structure where the interaction continues. However, the intensity of forces that enter the structure need not be the same. Depending on various factors like levels, water bodies, door placement etc., either the positive or the negative can have stronger presence.
If the structure is so designed that the positive forces override the negative forces then there is a beneficial release of bio-energy, which helps all the inmates to be healthy. Even after such reaction with the negative forces a positive cosmic surplus is always present in such a structure, which is the Supreme Being Himself. In such an atmosphere life is smooth and happy with every thing in life coming your way without any great struggle. It is a happy and healthy life for all the inhabitants.
If on the other hand the structure is built in such a manner that the negative forces override the positive then you have a weak bio-energy field which manifests as diseases in the occupants. The over bearing negative field makes your actions, efforts, thinking negative so that ultimately the whole life is ruined.
The science of Vaastu guides you about the rules you have to follow so that the structure has a positive atmosphere.