While the design and construction of envelopes for Passive House certified homes in central European climates is well developed and has achieved widespread acceptance and reliability, the same cannot be said in colder climate regions such as the United States’ upper Midwest (DOE climate zones 6 and 7) and Scandinavia. The objective of this research was to study some of the typical building performance issues relating to Passive House envelope construction for single family homes in cold climates by testing and developing a group of 8 envelope options. Typical issues include unfamiliarity with performance of thermal bridge details, added embodied energy and carbon due to increased insulation and structure, and increased risk of moisture damage due to thicker, multi-layered assemblies and smaller drying potentials. The basic envelope types were selected from case studies, then tested and developed to meet set levels of moisture safety, life cycle energy and carbon impacts, and Passive House thermal bridging and energy performance requirements. The envelope options were compared using a number of software tools. Athena life cycle analysis software was used to determine embodied energy, carbon, and environmental impacts of the envelope types. WUFI hygrothermal modeling was used to determine moisture performance and risk relating to mold growth. The EN ISO 6946 2-D U-value calculation protocol was used to investigate the loss of insulation value due to repetitive thermal bridges within a wall or roof assembly, while THERM software was used to determine the performance of a selection of thermal bridge details. Although significant variation was found in the performance of these eight envelope types, all of them were found capable of meeting the energy efficiency and thermal bridging requirements of the Passive House certification in a very cold climate, while maintaining moisture safety, durability, and significant life-cycle energy and carbon savings. These findings demonstrate that even in cold climates, a variety of envelope types can be used successfully for certified Passive Houses.

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