Building Science is still an unknown  subject even for the building industry so for the layman it is a huge mystery. Building science can be defined as the field of study in construction that focuses on air, heat, moisture, fire, lighting and the structure. Architects do the work now along with the design but there is no formal training in this field. A good building science not only requires every part of the building to work in a cohesive manner but it needs to be worked out in advance and not after the structure is built. That's where the expert comes in play. An eye opening article on this issue is written in the FineHomeBuilding  Spring/Summer edition 2012 and can be read here