Space Clearing is a specialized branch of Feng Shui that works at even deeper levels by cleansing and purifying the chi of a building, thus enhancing the quality and nature of the energy in the space.
Imagine, that everything that has happened in a space, as fights, quarrels or even disease, is capable of leaving its trace. These traces are not seen but can influence the inhabitants in a subtle way. Especially when you move to a new place clearing the energy can make a huge difference.
Feng Shui always works better and faster when done in conjunction with Space Clearing.
That is why I give a reduction when both are booked together.