Abstract

This thesis investigates how climate zone shifts affect the hygrothermal performance and durability of existing building wall assemblies designed under previous International Energy Conservation Code (IECC) requirements. As global climate change continues to alter temperature, humidity, and extreme weather patterns, building codes and climate classifications are increasingly challenged to keep pace with current and future environmental conditions. The research focuses on whether 2×6 wood-framed wall assemblies designed under the 2018 IECC remain resilient under updated climate zone classifications and future climate scenarios. A comparative analysis of four U.S. counties—Davidson (TN), Garfield (OK), Allegany (MD), and Marion (IN)—was conducted based on documented climate zone shifts between the 2018 and 2021 IECC. Hygrothermal simulations were performed using WUFI 2D under baseline (2020) and projected future climate conditions (2040 and 2080) using Future Typical Meteorological Year (FTMY) weather files aligned with a high-emissions SSP5 scenario. Performance metrics included relative humidity, water content by mass in sheathing materials, and isopleth-based mold growth risk. Results indicate that wall assemblies generally remain within acceptable moisture thresholds across several climate transitions; however, the risk of elevated relative humidity and mold potential increases under warmer, more humid future conditions, particularly in zones experiencing significant climate warming. Changes in vapor retarder requirements across climate zones further influence the resilience of assemblies, highlighting the importance of climate-responsive design strategies. The findings suggest that while many existing wall assemblies remain functional under moderate climate shifts, long-term climate change may compromise durability in specific regions, necessitating a reconsideration of vapor-retarder selection, insulation strategies, and code-based climate-zone definitions. This research contributes to a better understanding of how evolving climate classifications impact building envelope performance and informs future resilient design practices in the AEC industry.

Publication Date

5-2026

Document Type

Thesis

Student Type

Graduate

Degree Name

Architecture (M.Arch.)

Department, Program, or Center

Architecture, Department of

College

Golisano Institute for Sustainability

Advisor

Julius J. Chiavaroli

Advisor/Committee Member

Alissa De Wit-Paul

Advisor/Committee Member

Seth Holmes

Campus

RIT – Main Campus

Download

Share

COinS