Both Sha Chi and Si Chi—low feng shui energy vibes—are expressions of bad/negative feng shui energy. Sha Chi is translated as killing or attacking energy and Si Chi is low, decaying energy—the energy that feels lifeless and dying.
This bad feng shui energy can be created outside by the sharpness of a structure—man-made or natural—that points to your front door or any of the windows. This can be the sharp angle of a high-rise building that is energetically "slicing" through your window, for example, or even a big, bare tree branch that is "aiming" at your door or window.
Sha Chi, or sharp feng shui energy, can also be created inside the building. For example, when a sharp wall angle, called poison arrow, is pointing at your bed, there is a constant emission of attacking energy directed at your body. The feng shui of a T-junction house will tend to be bad and accumulate Sha Chi because of the strong and constant attacking energy directed towards the house.
In both cases the proximity is important; the further the attacking element is located from you or your house, the lesser its bad feng shui influence. This bad feng shui energy can lead to illness and depression for those who are exposed to it for a long amount of time.
Si Chi, or low feng shui energy, can be found outside. For example, in the land where the energy of human massacre, or other overwhelming human tragedies, is still potent. It can also be found inside the buildings that have strong geopathic stress, for example.
Si Chi is also present in houses with a lot of clutter, lack of order, as well as a lot of repressed emotions. Yes, houses do store all the negative energy that has been experienced inside their walls, that's why it is so important to have a space clearing session at least once a year. It is not hard to do, and the results are wonderful.
Avoiding Bad Feng Shui
We have all experienced, at one time or the other, the effects of "bad vibes", or bad feng shui energy in some spaces. Do your best to avoid these places and be sure there are no such feng shui energies in your home.
Strive to be surrounded by good feng shui energy—called Sheng Chi—in your home and office. Learn to create fresh and vibrant energy, as well as to clear low and stagnant energy. For example, your house may be free of external Sha Chi; which is excellent; however, your bedroom has Si Chi energy. This can explain why you often feel low energy and sad.