Interference lines are created when energy stagnates, flows incorrectly or doesn’t flow at all across the earth. These lines can cause dis-harmony or unhappiness for the occupants of a building or home. In Feng Shui they are called shar lines. When energy [Chi in Feng Shui] flows in balance with the environment, it brings happiness and harmony. When the energy or chi doesn’t flow correctly it can bring ill health and misfortune. By stopping these interference lines entering the property, it allows good chi to flow within the property boundary.