Buildings exert a considerable influence not only on outside environment, but also on human health, comfort, and productivity. In this interaction, the greatest role is assumed by the building envelope that acts as a filter permitting favourable external influences to enter the building, while rejecting or modifying unfavourable influences. All loads and functions to be assumed by the envelope arise from three significant components and their interactions: external environment, internal environment, and the envelope itself. An objective of modern construction activity is to approach the building envelope issue in a multidisciplinary and integral manner, so as to avoid potential problems while at the same time meeting human needs in an adequate way, at the lowest possible cost.