Realizing the energy efficiency aspirations of regulators necessitate innovations in many aspects of composite wall design.  Providing insulation in both interior and exterior wall cavities is increasingly becoming the norm to meet energy standards in mild and cold climates.  Innovation is happening for the attachment of claddings to accommodate different cladding types and varying levels of exterior insulation.  Advanced evaluation techniques are necessary to consider the impact of thermal bridging on heat flow and the structural capacity of complex wall designs.  More advanced evaluation than hand calculations using conventional assumptions is also needed to evaluate the condensation resistance of these designs.  Not considering how buildings actually operate and multi-dimensional construction when evaluating condensation resistance can unnecessarily restrain innovative and efficient wall systems in design practice. 

Many tools and resources are available for the evaluation of wall assemblies for condensation resistance, but all rely on assumptions or predications of the indoor moisture level and critical surface temperatures. The ability to predict indoor moisture levels and surface temperatures for how real buildings operate during varying outdoor conditions is crucial to efficient design.

This presentation will explore how available resources can be leveraged by practitioners without specialized knowledge of heat-air-moisture computer models.  Based on our research and experience, we will present:

• How indoor moisture levels for buildings with uncontrolled humidity can be best defined by the vapour pressure difference (∆VP) between the indoor and outdoor air
• How ∆VP can be incorporated into the evaluation of condensation resistance of any building envelope assembly
• Example generic solutions and advanced evaluation techniques for exterior and interior insulated wall assemblies and their limitations
• Why consider the whole building when evaluating the risk of condensation of wall assemblies, with comparisons to the evaluation of glazing condensation resistance