Integrated Methodology for Evaluation of Energy Performance of Building Enclosures: Part II — Examples of Application to Residential Walls

Abstract

It is often forgotten that the building sector consumes more energy than the transportation sector. To meet expectations and needs of our society, one must seek significant improvements in the efficient use of energy for this purpose. In many instances our normal approach based on conventional testing methods is not comprehensive enough. For instance, the thermal performance of a wall is defined by tests performed on dry materials, without considering the air and moisture movements. The energy performance of materials and building assemblies is affected by moisture and air flows. The authors believe that a more precise means of evaluation of the thermal performance of assemblies must be used to guide us in developing construction practices that lead to better performance. This should include consideration of air and moisture transfer under field conditions. The previous part of this study describes the limitations of conventional thermal resistance testing using calibrated hot boxes and explains that the effect of climate on thermal performance must also involve use of computer models that are capable of simultaneous calculations of heat, air, and moisture (HAM) transfer. In this study, the integrated testing and modeling methodology proposed is applied to a few selected residential walls to highlight the magnitude of air flow effects compared with steady-state thermal resistance without air flows. Effectively, to characterize energy performance of the building enclosure, one must use an integrated methodology that uses both testing and modeling. The study represents a first step in this direction.