Influence of input uncertainty on the 1-D hygrothermal simulation of composite walls in China

What is it about?

Hygrothermal simulations rely on fixed input values and predominantly yield deterministic outcomes. However, uncertainties in input parameters, such as inevitable experimental errors and the simplification of climate conditions, are unavoidable. Owing to the potential effects of inherent uncertainties on the reliability of simulation outputs, the analysis of the impact of input parameters on building hygrothermal performance has gradually transitioned from deterministic to uncertainty analyses, which help evaluate the influences of input uncertainties on the modeling results. This study proposes a probabilistic method to comprehensively evaluate input uncertainties in the simulated hygrothermal performance of 1-D composite walls in five thermal design zones in China. Specifically, input parameters are categorized into discrete (e.g., insulation type) and continuous (e.g., thermal conductivity) parameters. The discrete parameters form 160 basic simulation scenarios. For each scenario, 400 uniform random samples are generated within given ranges of continuous parameters using Latin hypercube sampling, resulting in 64,000 simulation cases. Heat flux, moisture flux, moisture content, interstitial condensation, mold growth and frost damage are used as indicators for the hygrothermal performance, and multiple linear regression analysis is used to determine the most influential continuous parameters. The results indicate that the thermal conductivity of insulation materials has the greatest influence on the average heat flux, interstitial condensation risk, mold growth risk, and freeze/thaw cycles. The moisture retention curve and vapor diffusion resistance factor of structural materials significantly influence the average moisture flux. The moisture retention curve of structural materials has the most influence on the average moisture content of the structural layer.

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Why is it important?

In the present work, a comprehensive simulation scheme at the component level is proposed to identify the most influential uncertain input parameters. Most previous studies have analyzed the influence of uncertain input parameters on the building's hygrothermal performance within a single climate zone. In contrast, this study encompasses an analysis across five thermal design zones in China, providing valuable references for many other regions with similar climate characteristics. Furthermore, the proposed comprehensive simulation scheme, which incorporates various hygrothermal performance evaluation indicators, insulation types, insulation materials, structural materials, and orientations, makes the identified key input parameters more generalizable than previous studies' findings.

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