The birth of Vastu Purush is narrated in an interesting story in Matsya Purana. Lord Shiva while fighting the demonAndhakasura, started perspiring profusely and from the sweat drops, a monstrous being was born. The child was so hungry that he gorged on everything around including the slain demon. He began to grow steadily, eating all that came near his mouth. He occupied almost all the surface of the earth, killing all the inhabitants and destroying the nature. All the Five Elements of the galaxy namely Earth, Water, Fire, Air & Sky suffered by the growth of this child and could not carry on their functions.
To protect the world, all of the Gods in heaven together pinned him down on to the ground with his head towards North East and feet towards South West and sat on different parts of his body and said that ‘Hence forth you will be known as ‘VASTUPURUSHA’ or ‘VASTHUDEVTA’. You will occupy any piece of earth with boundaries made on four sides. The people will offer you prayers and worship you. You can curse or favour the people who own or occupy any place of earth. If they make you feel happy and comfortable as you lay down on the earth you may favour them with boons. If not, you are allowed to curse and make them suffer’.
As per the direction the Vastu Purush lay, the five elements took their seats. So space occupied North East towards his head, Earth occupied South West towards his feet, Fire occupied South East towards his belly, Water occupied West towards his intestines and Air occupied North West towards his heart. These elements have to be satisfied in order to satisfy his hunger, else the deficiency creates negative energy. This is verified by scientific principals which confirm the elements residing in the corners of a 4 wall enclosed room. For eg:- South East gets most heat as the ultraviolet rays of the Sun cast maximum effect here. North East gets most energy being the confluence of the positive energy from North pole and Sun rising from East.
I believe that we were told important principals of life through stories so that they are interesting enough to be told and retold across generations. This story was meant to convey the importance of construction of a dwelling where you bind space in four walls and restrict the panch tatva inside the space. Then the South East seeks fire element and North West seeks air element. Vastu guides us as to how to maintain equilibrium of these elements to create harmonious energies in human dwellings. If a particular direction does not get a particular element, either a negative energy will be created, or the direction itself will suck the same from the environment even if it’s the people in the house. So in a house which is not vastu complaint, which means that each direction is not getting the element it desires, will lead to the inhabitants having low energy levels. This would in turn affect the emotions and thought process of the people. However a person who is spiritually oriented and is able to compensate for the negative energies in his dwelling with the strength and power of his own chakras will be immune to the effects of such vastu.
I would also like to add that if you spend more time or dwell in a direction which is Vastu complaint the non Vastu complaint areas of the house are unlikely to affect you. So for example, if North West which is supposed to have the air element, has no windows, and you use it as a storeroom, you will have no ill effect because you would rarely use that room. Also if your South West is your living area instead of bedroom, it is worthwhile to spend more family time in the living area.
So the conclusion is that non complaint Vastu can affect your emotions and hence thought process by the deficient energy in the dwelling. But it is still insignificant compared to the positive energy you get from meditation, your own will power and the energy you get from several other sources outside of home or office. People sometime pay a lot of emphasis on Vastu being the reason for disharmony, bad luck, ill health or losses and try hard for suitable remedies. But I think that it is more worthwhile to focus on building positive energy within yourself through self transformation and paying emphasis on good behaviour, tolerance, compassion, forgiveness and love.