Energy would follow a particular pattern on a plain plot. Once the building is placed within it, there is obviously a rough alteration in the flow.
The design of the building also introduces varied shapes into the energy flow. The permutations that arise in an architects mind as to the shape and design of a house could be a Feng Shui practitioner's nightmare. The shapes of the building as well as the components within affect the residents to a great extent.
People spend most of their time within a building and hence it would affect them more than trees or roads which hare outside. Hence buildings affect the Feng Shui of an area to a great extent.
There are further changes too, as the building is constructed using alien material from outside. The construction material is not of nature's origin as in the past and contains chemicals.
Buildings gain more importance in today's architecture, because there are multi-storied apartments where resident live very high and faraway from the plot or the environment.