Run a hygrothermal (moisture) analysis of a proposed wall assembly to check for long-term moisture and mold risk during BECx design review

Steps

1. Use ANSI/ASHRAE Standard 160, Criteria for Moisture-Control Design Analysis in Buildings, for performance-based moisture design criteria that account for climate, construction type, and HVAC operation
2. Confirm the standard sets criteria for moisture design loads, hygrothermal analysis methods, and acceptable moisture performance of the envelope
3. Apply the standard's mold-growth criteria in the analysis: as of the 2016 revision, the 30-day running average relative humidity at a material surface must remain below 80% when the 30-day running average surface temperature is between roughly 5°C (41°F) and 40°C (104°F)
4. Run the hygrothermal simulation (e.g., using WUFI or comparable software) to predict moisture and temperature conditions within the assembly over an annual or multi-year cycle, using the load and boundary-condition assumptions ASHRAE 160 specifies
5. Confirm which edition of Standard 160 the project's OPR or code officially requires, since the standard has been revised (e.g., 2016, 2021 editions) and criteria have changed between revisions (including simplified indoor relative-humidity limits)
6. Feed identified high-risk assemblies back into the BECx design-phase peer review for detail or material revision