Architects and engineers have recently been introduced for the first time to some very powerful tools that simulate the hygrothermal performance of building envelopes. These tools have been extremely useful in capturing the response of the envelope to interior and exterior hygrothermal environmental loading.

The hygrothermal response of a wall is strongly dependent on the material sequencing of the wall structure, embedded subsystems (wall-window interfaces), and the material thermal and moisture properties of each layer. However, some of these system characteristics, “real performance attributes,” can only be captured in the field or in carefully performed laboratory investigations and are needed inputs to advanced models.

To a designer/architect who is required to select and design an envelope for thermal and moisture performance, this task can be overwhelming. Today's engineers and architects have not been trained sufficiently in the area of heat and mass transfer of building envelopes, in particular, building physics; however, they are often tasked with selecting envelopes that perform well. At the same time, certain constraints such as construction costs, projected maintenance costs, heat and cooling annual costs, and service life projection all enter the decision-making process. In this paper, an innovative approach is presented that allows the architect or engineer to select a wall cladding based on moisture engineering principles that have already undergone a series of laboratory-determined hygrothermal material property characterizations, whole wall drainage and drying testing, real environmental analysis, and advanced hygrothermal performance assessment. This new method can be used for any type of envelope system, as the approach is clear and simple and includes the state-of-the-art in current building envelope performance analysis. This paper will provide the foundation and rationale for the development of this next generation of wall design tools for architects and engineers using EIFS wall systems as their application.