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Moisture Design Periods for Hygrothermal Simulations: Addressing Durability Challenges in Swedish Building Assemblies

Tahir, Assad LU orcid ; Abdul Hamid, Akram LU orcid ; Wallentén, Petter LU orcid and Arfvidsson, Jesper LU (2025) 2025 Buildings XVI Conference
Abstract
Moisture‐induced deterioration is critical to building envelope durability in cold and temperate climates. To propose a new framework for selecting moisture design periods (MDPs) in Swedish building assemblies that capture sever moisture conditions more accurately, this paper evaluates different methods for producing MDPs. Using a 30‐year historical weather dataset as a benchmark, we compared simulations driven by five climate file sources. These included historical records, a Severity Index (Isev)–based method, WUFI climate files, Meteonorm synthetic data, and Moisture Research Centre (MRC) data for three Swedish cities. For the sake of comparison, two different demonstrative wall assemblies (brick and wooden) were employed in the... (More)
Moisture‐induced deterioration is critical to building envelope durability in cold and temperate climates. To propose a new framework for selecting moisture design periods (MDPs) in Swedish building assemblies that capture sever moisture conditions more accurately, this paper evaluates different methods for producing MDPs. Using a 30‐year historical weather dataset as a benchmark, we compared simulations driven by five climate file sources. These included historical records, a Severity Index (Isev)–based method, WUFI climate files, Meteonorm synthetic data, and Moisture Research Centre (MRC) data for three Swedish cities. For the sake of comparison, two different demonstrative wall assemblies (brick and wooden) were employed in the simulations. Mold growth predictions were quantified using the VTT Mold Index model, identifying climates most conducive to fungal proliferation. Our results reveal that while the Isev‐derived and standard WUFI climate files track historical outcomes under high wind-driven rain (WDR) exposures, they systematically underpredict mold risk in orientations with lower moisture loads as well as for lightweight wood assemblies. Conversely, long‐term historical data provide a more conservative yet reliable measure of moisture risk, especially for critical envelope components. Although initially developed for broader climate zones, the Severity Index approach shows promise in pinpointing critical scenarios but likely requires regional calibration for Swedish conditions. These findings underscore the importance of tailoring climate inputs when defining MDPs: adopting a suitably conservative dataset is key to mitigating latent mold risks and ensuring robust building enclosure performance. This study provides a methodology for aligning climate‐based design practices with regional meteorological variations, thereby strengthening moisture management strategies and promoting both the durability and healthfulness of buildings in cold climates. (Less)
Please use this url to cite or link to this publication:
author
; ; and
organization
publishing date
type
Chapter in Book/Report/Conference proceeding
publication status
published
subject
host publication
Buildings XVI : Thermal Performance of the Exterior Envelopes of Whole Buildings - Thermal Performance of the Exterior Envelopes of Whole Buildings
publisher
ASHRAE
conference name
2025 Buildings XVI Conference
conference location
Clearwater Beach, FL, United States
conference dates
2025-12-08 - 2025-12-11
DOI
10.63044/b16moh28
language
English
LU publication?
yes
id
6efe0dcd-b2a7-4adf-9cb4-57438d680d3d
date added to LUP
2026-06-15 02:57:01
date last changed
2026-06-15 10:58:40
@inproceedings{6efe0dcd-b2a7-4adf-9cb4-57438d680d3d,
  abstract     = {{Moisture‐induced deterioration is critical to building envelope durability in cold and temperate climates. To propose a new framework for selecting moisture design periods (MDPs) in Swedish building assemblies that capture sever moisture conditions more accurately, this paper evaluates different methods for producing MDPs. Using a 30‐year historical weather dataset as a benchmark, we compared simulations driven by five climate file sources. These included historical records, a Severity Index (Isev)–based method, WUFI climate files, Meteonorm synthetic data, and Moisture Research Centre (MRC) data for three Swedish cities. For the sake of comparison, two different demonstrative wall assemblies (brick and wooden) were employed in the simulations. Mold growth predictions were quantified using the VTT Mold Index model, identifying climates most conducive to fungal proliferation. Our results reveal that while the Isev‐derived and standard WUFI climate files track historical outcomes under high wind-driven rain (WDR) exposures, they systematically underpredict mold risk in orientations with lower moisture loads as well as for lightweight wood assemblies. Conversely, long‐term historical data provide a more conservative yet reliable measure of moisture risk, especially for critical envelope components. Although initially developed for broader climate zones, the Severity Index approach shows promise in pinpointing critical scenarios but likely requires regional calibration for Swedish conditions. These findings underscore the importance of tailoring climate inputs when defining MDPs: adopting a suitably conservative dataset is key to mitigating latent mold risks and ensuring robust building enclosure performance. This study provides a methodology for aligning climate‐based design practices with regional meteorological variations, thereby strengthening moisture management strategies and promoting both the durability and healthfulness of buildings in cold climates.}},
  author       = {{Tahir, Assad and Abdul Hamid, Akram and Wallentén, Petter and Arfvidsson, Jesper}},
  booktitle    = {{Buildings XVI : Thermal Performance of the Exterior Envelopes of Whole Buildings}},
  language     = {{eng}},
  publisher    = {{ASHRAE}},
  title        = {{Moisture Design Periods for Hygrothermal Simulations: Addressing Durability Challenges in Swedish Building Assemblies}},
  url          = {{http://dx.doi.org/10.63044/b16moh28}},
  doi          = {{10.63044/b16moh28}},
  year         = {{2025}},
}