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El objetivo principal del diseño de edificios es el proveer ambientes interiores productivos, confortables y saludables para sus ocupantes en balance con la eficiencia energética. Aberturas interiores de edificios, tales como las de escaleras, son huellas importantes para el intercambio de calor, aire, humedad y contaminantes. Los flujos de aire interzonas a través de aberturas horizontales no han sido estudiados profundamente debido a su naturaleza transiente y altamente inestable, la complejidad para realizar experimentos, y la escasez de datos experimentales disponibles. La Dinámica de Fluidos Computacional (CFD por su acrónimo en inglés) es una excelente herramienta para avanzar en la comprensión de este fenómeno. En este artículo, se aplica CFD para evaluar el desempeño de cinco modelos de turbulencia de dos ecuaciones: k-ε estándar, k-ε RNG, k-ε realizable, k-ω estándar y k-ω SST, para predecir las condiciones del aire interior y los flujos de la masa de aire ascendente que fluyen a través de una abertura horizontal en una casa de ensayos de dos pisos a escala real. La investigación incluye seis casos con diferentes gradientes de temperatura entre los dos pisos y tres estrategias de ventilación que representan convección natural y mixta. Los principales resultados muestran que las temperaturas son predichas correctamente por todos los modelos de turbulencia, mientras que las velocidades del aire simuladas presentan variaciones mayores entre los modelos de turbulencia evaluados. En general, los modelos k-s estándar y k-ε realizable son los más precisos para predecir las temperaturas interiores y las velocidades de aire para la convección natural y mixta, respectivamente. Además, los flujos de la masa de aire ascendente a través de la abertura horizontal estimados por ambos modelos de turbulencia concuerdan muy bien con los datos experimentales. The main objective in building design is to balance energy efficiency with healthy, comfortable and productive indoor environments for the occupants. Interior building openings, such as stairwells, are significant paths for the exchange of heat, air, moisture and pollutants. The interzonal airflow through horizontal openings has not been profoundly studied because of its highly transient and unstable nature, the complexity of carrying out experiments and the limited availability of experimental data. Computational Fluid Dynamics (CFD) is an excellent tool to advance the understanding of this phenomenon. In this paper, CFD is applied to evaluate the performance of five two-eddy viscosity turbulence models (k-ε standard, k-ε RNG, k-ε realizable, k-ω standard and k-ω SST) to predict indoor air conditions and upward mass airflows through a horizontal opening in a full-scale, two-story test hut. This study involves six cases with different temperature gradients between the two floors and with three ventilation strategies that represent natural or mixed convection. The main results show that the temperatures are well predicted by all turbulence models while the simulated air speeds present larger variations among the evaluated turbulence models. Overall, the k-s standard and k-s realizable models are the most accurate ones to predict indoor temperatures and air speeds for natural and mixed convection, respectively. Moreover, the upward mass airflows through the horizontal opening estimated by both turbulence models are in very good agreement with the experimental data.

La predicción de patrones de flujo de aire, velocidad, temperatura, humedad y concentración de contaminantes son requeridos para el diseño de ambientes interiores saludables y confortables. La Dinámica de Fluidos Computacional (CFD) es la técnica más avanzada para modelar y predecir los flujos de aire en ambientes cerrados. Sin embargo, los principales errores en los modelos CFD y en sus resultados están relacionados con el factor humano. Los principiantes en modelación CFD no cuentan con las habilidades, experiencia y juicio ingenieril para generar modelos robustos y confiables. Este proceso no es intuitivo y los nuevos usuarios necesitan orientación. Este artículo busca proveer información más completa sobre la modelación CFD de casos básicos de convección natural, forzados y mixtos que permitirán a los nuevos usuarios adquirir las habilidades y confianza. La modelación CFD incluye la generación de malla, definición de criterios de convergencia y factores de relajación, y la evaluación de modelos de turbulencia para cada caso. Los resultados muestran que es necesaria la experiencia de los usuarios en cada paso de la modelación CFD, incluso para casos simples de convección. Prediction of airflow pattern velocities, temperature, moisture and pollutants concentration is required to design healthy and comfortable indoor environments. Computational Fluid Dynamics (CFD) is the most advanced technique to model and predict the airflow in enclosed environments. However, the main errors in CFD models and their results are linked to the human factor. Beginners on CFD modeling do not account with skills, experience and engineering judgment to generate robust and reliable CFD models. This process is not intuitive and new CFD users need guidance. This paper aims to provide more complete information on CFD modeling of basic natural, forced and mixed convection cases that would allow CFD beginners to acquire skills and confidence. CFD modeling includes mesh generation, setting convergence criteria and under-relaxation factors, and evaluating different turbulence models for each convection case. Results show that users´ expertise is needed in each step of CFD modeling, even for these basic convection cases.

Full-scale stud cavities were constructed in a climate-controlled chamber to investigate the capacity of wall cavities under experimental conditions to contain mold products, emanating from studs with 10% of their surfaces covered with mold, from penetrating the indoor space. The project investigated the transport of microbical volatile organic compounds (MVOCs), which can be byproducts of mold growth, through the building envelope, and assesses whether the concentration of MVOCs was related to six experimental parameters stated below. The tests were initially designed primarily to study the movement of fungal spores. Later, additional information was collected to investigate the movement of MVOCs. Full size wall assemblies of residential wood frame buildings were constructed, and subjected to air infiltration rates typical of houses in the Quebec region, Canada. A stainless steel sampling chamber, simulating the indoor space, was constructed to encase the inner face of the central stud cavity of the specimens, and to provide controlled depressurization for the air infiltration. The parameters that may influence spores and MVOCs movement selected for the investigation were the air leakage characteristics (air leakage path and rate) and wall configurations (insulation, vapour barrier and sheathing material). The analysis of VOCs was performed using gas chromatography/ mass spectrometry (GC/MS) to identify the volatile species in the stud space, the interior of the sampling chamber and the ambient laboratory air. The results were analyzed using multiple regression analysis to determine the transport through the building envelope.

In site situations where rain water penetrates into the stud cavity of the building envelope and concentrates at the bottom, the wet bottom plate becomes a moisture loading source. This moisture evaporates creating a vapor pressure profile that decreases with height and causes a corresponding absorption-evacuation mass profile through the sheathing. Such profiles were observed during an experiment designed to develop a test method to compare the relative performance of different wall configurations. In this experiment 31 wall assemblies were subjected to steady-state climatic loadings and uniform moisture loading consisting of water trays on load cells at the bottom plate within the stud cavities of the wall assemblies. In this paper, a new method is used to develop evacuation profiles due to evaporation of moisture sources in stud cavities of building envelope panels of various configurations. This method takes into account the vapor-pressure-vs.-height and vapor-mass-vs.-height profiles.

In this paper, the development and benchmarking of a newly developed whole building hygrothermal model are presented. The model considers the building as a system and accounts for the dynamic heat, air and moisture (HAM) interaction between building envelope components and indoor environmental conditions including HVAC systems, moisture and heat sources. The methodology adapted in this work is to develop and validate two primary models: building envelope and indoor models independently and couple them to form the whole building hygrothermal model. After successful integration of the models, the whole building hygrothermal model is benchmarked against internationally published numerical and experimental test results. The holistic model is used to assess building enclosures durability, indoor conditions (temperature and relative humidity), occupant comfort, and energy efficiency of a building in an integrated manner.

Horizontal openings in dwellings, such as staircases, provide large paths for air and moisture transport between floors. They play an important role in the moisture distribution from a moisture-source room to the rest of the house. The phenomenon, however, has only been barely studied. The objective of this work is to study the moisture transport through a horizontal opening under different ventilation strategies, ventilation rates, temperature differences between the upper and lower room, and locations of the moisture source. The study was carried out in a full-scale test-hut composed of two rooms connected by a large horizontal opening of 1.19m x 0.91m x 0.22 m. The inner dimensions of each room are 3.62m x 2.44m x 2.43m. Moisture was generated for 10 hours at known rates (107±2 and 113±2 g/h in the first and second floor, respectively) followed by 14 hours without moisture generation; the RH and temperatures were measured across both rooms. Different ventilation strategies were studied: no ventilation, net flow up-to-down, and independent ventilation for each room. Also, temperature difference between the two rooms was set between -3.5ºK to 3ºK. The main results show that moisture exchange between the two rooms starts when the moisture generation begins and two-way airflow exists through the opening. A colder upper room promotes moisture and air exchange between the two rooms even if the net flow is downward. Additionally, it was found that air was not well mixed in each room, thus significant humidity ratio variations were found across each room and between the both rooms, especially when the upper room temperature was higher.