Impacto da variação das condições de contorno no projeto de norma ABNT de simulação de transporte de umidade

Abstract

Moisture is one of the main causes of building pathologies. It affects both the durability of building components and the healthiness of indoor environments. Various international standards address issues related to the hygrothermal performance of buildings, but at the national level, there are still many gaps. The ABNT Humidity Working Group conducts discussions and research on the topic of hygrothermal performance in buildings. Currently, the development of an ABNT standard project is underway, aiming to establish a national standard for the computer simulation of hygrothermal performance in buildings. This research aims to analyze the ABNT standard project titled “Computer Simulation of the Hygrothermal Behavior of Walls – Procedure” regarding its sensitivity to variations in boundary conditions related to moisture production, usage, and occupancy. The method consists of applying the proposed conditions in the ABNT standard project and analyzing the sensitivity to variations in boundary conditions through computer simulations of heat and moisture transport. Firstly, the boundary conditions of the ABNT standard project were presented, and variations for analysis were defined. Then, computational simulations of 104 models with different variations for analysis were executed, using the EnergyPlus 9.4 and WUFI Pro 6.7 programs. Finally, the results were analyzed using sensitivity analysis through the complete factorial variance method ANOVA. As results, considering the conditions of the analyzed construction system and the climate used, the most sensitive variable for the criterion of total wall moisture content was directed rain and indoor occupancy. For the criterion of surface condensation on the internal surface, the most sensitive variable was indoor occupancy. Regarding temperature profile criteria, natural ventilation and indoor occupancy were the most sensitive variables. For relative humidity profile criteria, the most sensitive variables were indoor occupancy and directed rain. In the criterion of filamentous fungi formation, natural ventilation exhibited greater sensitivity. Directed rain proved to be an influential variable present in several analysis criteria, underscoring the importance of selecting a reliable climatic file with realistic directed rain conditions, as well as using simulation tools that consider directed rain in their mathematical models. Indoor occupancy also played an important role in the results, as the occupancy of the building results in significant internal heat and vapor production, which can contribute to the formation of wall pathologies. In general, it was observed that changes in variables significantly impact the results, highlighting the importance of the standard project establishing appropriate boundary conditions that align with the reality of our country.