Development of a Hygrothermal Simulation Tooil (HAM-BE) for Building Envelope Study PDF Download
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Author: Qinru Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
To prevent the building envelope from moisture-related damages, it is essential to predict the building envelope's hygrothermal performance through a scientific approach, and further to improve the design and construction. In this thesis, an advanced numerical tool (HAM-BE) was developed to simulate the combined heat, air and moisture (HAM) transport in the building envelope. The state of the art knowledge of heat and mass transfer in building materials was applied. The major features of HAM-BE are: multi-dimensional and transient coupling of heat and moisture transport; air convection integrated in hygrothermal simulation through Darcy-Boussinesq approximation; heat transfer mechanisms of conduction and convection of sensible and latent heat; moisture transport mechanisms of vapor diffusion, capillary suction and air convection; material database of common building materials in North America; experimental settings or hourly weather data as boundary conditions; and setting moisture loading inside the materials or along the surfaces of the building envelope's hidden or exposed components to simulate the wetting process. A commercial finite element solver was chosen to solve the governing partial differential equations (PDEs) of hygrothermal transport. This approach provided building science researchers the flexibility to build, modify, and maintain their modeling work efficiently. Validation of HAM-BE included inter-model comparison with benchmarking cases of the HAMSTAD project and comparison between numerical simulation with data of the Collaborative Research and Development (CRD) project measured by fellow students under the supervision of Drs Fazio and Rao. Through validation work, HAM-BE was proven to have great potential as an accurate and reliable research tool for the building envelope study. As the extension of the CRD investigation, parametric study was carried out to estimate the drying performance of wood-frame walls under the climatic conditions of Montreal and Vancouver. It is demonstrated that the climate condition has the most significant influence to the drying process of the wet components in wall assemblies. The drying process occurs mainly in the summer season, and is largely restrained in the winter season. To improve outward drying, the cladding materials should have high vapor permeance, especially the sheathing membrane. The sheathing board with higher vapor permeance also facilitates drying. Under the investigated climates, the polyethylene vapor barrier at the warm side of the wall is not beneficial, rather restricts the possibility of inward drying.
Author: Qinru Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
To prevent the building envelope from moisture-related damages, it is essential to predict the building envelope's hygrothermal performance through a scientific approach, and further to improve the design and construction. In this thesis, an advanced numerical tool (HAM-BE) was developed to simulate the combined heat, air and moisture (HAM) transport in the building envelope. The state of the art knowledge of heat and mass transfer in building materials was applied. The major features of HAM-BE are: multi-dimensional and transient coupling of heat and moisture transport; air convection integrated in hygrothermal simulation through Darcy-Boussinesq approximation; heat transfer mechanisms of conduction and convection of sensible and latent heat; moisture transport mechanisms of vapor diffusion, capillary suction and air convection; material database of common building materials in North America; experimental settings or hourly weather data as boundary conditions; and setting moisture loading inside the materials or along the surfaces of the building envelope's hidden or exposed components to simulate the wetting process. A commercial finite element solver was chosen to solve the governing partial differential equations (PDEs) of hygrothermal transport. This approach provided building science researchers the flexibility to build, modify, and maintain their modeling work efficiently. Validation of HAM-BE included inter-model comparison with benchmarking cases of the HAMSTAD project and comparison between numerical simulation with data of the Collaborative Research and Development (CRD) project measured by fellow students under the supervision of Drs Fazio and Rao. Through validation work, HAM-BE was proven to have great potential as an accurate and reliable research tool for the building envelope study. As the extension of the CRD investigation, parametric study was carried out to estimate the drying performance of wood-frame walls under the climatic conditions of Montreal and Vancouver. It is demonstrated that the climate condition has the most significant influence to the drying process of the wet components in wall assemblies. The drying process occurs mainly in the summer season, and is largely restrained in the winter season. To improve outward drying, the cladding materials should have high vapor permeance, especially the sheathing membrane. The sheathing board with higher vapor permeance also facilitates drying. Under the investigated climates, the polyethylene vapor barrier at the warm side of the wall is not beneficial, rather restricts the possibility of inward drying.
Author: Scott Walbridge
Publisher: Springer Nature
ISBN: 9811910049
Category : Technology & Engineering
Languages : en
Pages : 689
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Book Description
This book comprises the proceedings of the Annual Conference of the Canadian Society of Civil Engineering 2021. The contents of this volume focus on specialty conferences in construction, environmental, hydrotechnical, materials, structures, transportation engineering, etc. This volume will prove a valuable resource for those in academia and industry.
Author: João M.P.Q. Delgado
Publisher: Springer Science & Business Media
ISBN: 3642350038
Category : Technology & Engineering
Languages : en
Pages : 73
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Book Description
This book presents a critical review on the development and application of hygrothermal analysis methods to simulate the coupled transport processes of Heat, Air, and Moisture (HAM) transfer for one or multidimensional cases. During the past few decades there has been relevant development in this field of study and an increase in the professional use of tools that simulate some of the physical phenomena that are involved in Heat, Air and Moisture conditions in building components or elements. Although there is a significant amount of hygrothermal models referred in the literature, the vast majority of them are not easily available to the public outside the institutions where they were developed, which restricts the analysis of this book to only 14 hygrothermal modelling tools. The special features of this book are (a) a state-of-the-art of numerical simulation tools applied to building physics, (b) the boundary conditions importance, (c) the material properties, namely, experimental methods for the measurement of relevant transport properties, and (d) the numerical investigation and application The main benefit of the book is that it discusses all the topics related to numerical simulation tools in building components (including state-of-the-art and applications) and presents some of the most important theoretical and numerical developments in building physics, providing a self-contained major reference that is appealing to both the scientists and the engineers. At the same time, this book will be going to the encounter of a variety of scientific and engineering disciplines, such as civil and mechanical engineering, architecture, etc... The book is divided in several chapters that intend to be a resume of the current state of knowledge for benefit of professional colleagues.
Author: Menghao Qin
Publisher: LAP Lambert Academic Publishing
ISBN: 9783843372220
Category :
Languages : en
Pages : 248
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Book Description
Buildings account for 35 percent of the world s energy use and a similar percentage of CO2 emissions. In order to ensure adequate energy supplies and to curtail the growth of CO2 emissions, it is essential that building energy consumption is significantly reduced. One way this can be achieved is through the introduction of sustainable building design enabled by innovative building simulation tools, for example the whole building heat, air and moisture (HAM) transfer model. The hygrothermal transfer between building envelopes and indoor air has a significant influence on the indoor environment and energy performance of buildings. However in most applications, building envelope designers attempt to predict the hygrothermal performance of an individual building element by uncoupling the system from interactions of the other envelope components to both indoor/outdoor environments. A more advanced building performance evaluation approach requires the direct coupling of all building envelope systems with HVAC systems and indoor/outdoor environments. The book will focus on the development of a coupled HAM model for whole building simulation.
Author: Fitsum Tariku
Publisher:
ISBN:
Category : Buildings
Languages : en
Pages : 0
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Book Description
The current indoor, building envelope and energy analysis tools are in the form of stand-alone packages, where there is no direct link among them but rather simplifying assumptions are made on the indoor conditions or building envelope when designing for one. For example, indoor models attempt to predict the indoor condition with a simplified approach or no coupling with the building components, which in fact could have a moisture buffering effect. Building envelope models use predefined simple indoor environmental conditions in assessing the hygrothermal performance of a particular building component. Energy models usually ignore the moisture effect on the thermal transport and storage properties of materials. Incorrect prediction of indoor humidity condition and ignoring moisture effect in the energy calculation may lead to over or under sizing of HVAC equipments and the associated effects on building enclosure moisture performance and occupants' comfort and health. In reality, the indoor environmental conditions, more specifically, temperature and relative humidity, are unknown quantities, and have to be determined from the heat and mass balance in the zone considering the heat and mass transfer across the building enclosure, the internal heat and moisture generated by occupants and their activities, and the heat and moisture supply from mechanical systems depending on the mode of operation of the building. In this research work, a whole building hygrothermal model, which considers the building as a system and deals with the dynamic heat, air and moisture (HAM) interactions among building envelope components, indoor environment and mechanical systems, is developed. The model takes into account the three interrelated and coupled components and evaluates the indoor temperature and relative humidity, building enclosure moisture performance and energy efficiency of the building in an integrated manner on a single platform. The model along with two primary models, namely building envelope and indoor models, are benchmarked against internationally published analytical, numerical and experimental test cases. After successful benchmarking, its usefulness in practical applications are demonstrated through indoor humidity modeling of an existing building, and evaluation of the subsequent retrofit options to attain indoor humidity that is favorable to occupants' comfort and health and at the same time high energy efficiency and durable building. The whole building heat and moisture analysis that are carried out in this research work underlines the importance of an integrated design approach in designing new buildings or retrofitting existing buildings in order to attain an optimized building performance.
Author: J. Carmeliet
Publisher: CRC Press
ISBN: 1000151298
Category : Technology & Engineering
Languages : en
Pages : 1044
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Book Description
This text provides a broad view of the research performed in building physics at the start of the 21st century. The focus of this conference was on combined heat and mass flow in building components, performance-based design of building enclosures, energy use in buildings, sustainable construction, users' comfort and health, and the urban micro-climate.
Author: Matthew R Hall
Publisher: Elsevier
ISBN: 0857096168
Category : Technology & Engineering
Languages : en
Pages : 809
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Book Description
The construction of earth buildings has been taking place worldwide for centuries. With the improved energy efficiency, high level of structural integrity and aesthetically pleasing finishes achieved in modern earth construction, it is now one of the leading choices for sustainable, low-energy building. Modern earth buildings provides an essential exploration of the materials and techniques key to the design, development and construction of such buildings. Beginning with an overview of modern earth building, part one provides an introduction to design and construction issues including insulation, occupant comfort and building codes. Part two goes on to investigate materials for earth buildings, before building technologies are explored in part three including construction techniques for earth buildings. Modern earth structural engineering is the focus of part four, including the creation of earth masonry structures, use of structural steel elements and design of natural disaster-resistant earth buildings. Finally, part five of Modern earth buildings explores the application of modern earth construction through international case studies. With its distinguished editors and international team of expert contributors, Modern earth buildings is a key reference work for all low-impact building engineers, architects and designers, along with academics in this field. Provides an essential exploration of the materials and techniques key to the design, development and construction of modern earth buildings Comprehensively discusses design and construction issues, materials for earth buildings, construction techniques and modern earth structural engineering, among other topics Examines the application of modern earth construction through international case studies
Author: Arianna Brambilla
Publisher: Woodhead Publishing
ISBN: 0128210982
Category : Technology & Engineering
Languages : en
Pages : 201
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Book Description
One in three homes, on average, suffer from excessive dampness and mould proliferation, with significant health and economic impacts. The combination of new construction methodologies, stricter airtightness requirements and the changing social and cultural context that influences the way we live inside buildings has created unprecedented challenges for the built environment. In modifying indoor and outdoor environments and the building envelopes that serve as a filter between the two, we are changing the physical parameters of the ways in which buildings behave and respond to climatic stimuli. Understanding and predicting the way in which buildings and moisture may interact should be an important step in the design process, aiming to minimise possible negative long-term consequences. Understanding and predicting the way in which buildings and moisture may interact is, today more than ever, essential yet difficult, as the experience of the past has lost its applicability. Moisture-related issues never have a simple solution, since they involve multiple factors, including design, construction, maintenance, materials, climate and occupation pattern. Thus, while the topic is attracting growing attention among researchers, designers and practitioners, the pace with which actual change is occurring is still too slow. Moisture and Buildings provides a critical overview of current research, knowledge and policy frameworks, and presents a comprehensive analysis of the implications of moisture and the importance of accounting for it during the design process. It responds to the urgent need for a systematic organization of the existing knowledge to identify research gaps and provide directions for future developments. The ultimate goal is to increase awareness of the multifaceted implications of hygrothermal phenomena and promote integrated design processes that lead to healthier and more durable constructions. Presents advanced knowledge on hygrothermal processes and their interaction with buildings Integrates the three key areas of moisture transport and its impact on buildings, including durability, human health and comfort Considers the most useful computational tools for assessing moisture and building interactions Includes a section on the main European, American and Australian building codes Explains the risks of mold growth to human health, including growth models to assessment methods
Author: Nathan Mendes
Publisher: Springer Nature
ISBN: 3030315746
Category : Science
Languages : en
Pages : 253
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Book Description
This book is the second edition of Numerical methods for diffusion phenomena in building physics: a practical introduction originally published by PUCPRESS (2016). It intends to stimulate research in simulation of diffusion problems in building physics, by providing an overview of mathematical models and numerical techniques such as the finite difference and finite-element methods traditionally used in building simulation tools. Nonconventional methods such as reduced order models, boundary integral approaches and spectral methods are presented, which might be considered in the next generation of building-energy-simulation tools. In this reviewed edition, an innovative way to simulate energy and hydrothermal performance are presented, bringing some light on innovative approaches in the field.
Author: Daniel Haeyoung Chung
Publisher:
ISBN:
Category : Buildings
Languages : en
Pages : 337
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Book Description
Predicting building envelope behavior over time can be difficult due to the uncertainty and complexity of the environment, materials and processes that influence heat, air, and moisture (H.A.M.) transport through the assembly. While the variability in outdoor weather's impact on H.A.M. analysis for envelopes has been studied over one-year prediction periods, long-term multi-year predictive simulations have not been well studied. Similarly, degradation and material variability are known to impact long-term envelope H.A.M. behavior, yet there has been limited documentation on predictive studies that integrate these areas into a useful framework to inform a design process. Thus, the primary objective of this dissertation is to create a novel method of determining probabilistic distributions of envelope moisture behavior outcomes that also includes variation from degradation, so that the results can augment decision frameworks for building envelope design. To fulfill the objective the research work explored four tasks. (1) The investigation of available probabilistic input distributions for building envelope simulations. Here inputs include weather conditions and material properties. (2) The stochastic investigation of the impact of variable multi-year weather on H.A.M. analysis outcomes. (3) The integration of time-dependent loadings and degradation modeling coupled with H.A.M. analysis (i.e. multi-year weather, indoor climate variation and insulation aging). (4) The creation of envelope metamodels (based on the probabilistic analysis using H.A.M. and degradation models) to expedite optimization studies. These are derived from the Monte Carlo studies via regression analysis. The investigation of available data resulted in the determination that while stochastic weather data is available, important aspects of rainfall and longwave radiation (from the sky) may be missing for many locations. Datasets regarding stochastic material properties are limited and require compilation from multiple studies. These deficiencies should be addressed by the industry to improve predictive capabilities and enhance the understanding of uncertainty in envelope analysis. The stochastic investigation of the analysis duration for building envelopes determined that variable weather for 10-year simulation periods had significant impact on the H.A.M. behavior. In comparison to frequently used one-year simulations, the 10-year results demonstrated much greater risks of undesirable moisture related outcomes (such as mold growth and corrosion). Currently ASHRAE standard 160 recommends that H.A.M. simulations be performed over either a reference year or a 10-year period. While ASHRAE provides reference year data, no guidance is given on selecting a 10-year weather period. Given the significantly higher risks demonstrated in this dissertation when using 10-year periods, this should be addressed in future research to better characterize long-term envelope behavior. The results from integrating time-dependent loadings and degradation coupling with H.A.M. analysis showed mixed results. Of the five coupled models studied, the two with the greatest influence on the H.A.M. behavior were longwave radiation exchange and wood decay. Wood decay while statistically infrequent had showed significantly accelerated mass loss when strongly coupled in the simulation model. Longwave radiation exchange greatly impacted moisture transport. Out of all the models studied, those that included longwave radiation exchange head the highest levels of moisture content. Further research including validation studies are needed to improve the use of longwave radiation exchange in envelope analysis. The results from the regression analyses and the optimization studies showed that the general framework for creating the metamodels is fairly robust. Metamodels were created with reasonable R-squared and error values from Monte Carlo trials to predict moisture related outcomes (i.e. moisture content, mold growth, and corrosion). These metamodels were demonstrated in a multi-objective optimization process that revealed in the assemblies studied that there is a general inverse relationship between moisture optimization and thermal transmittance. As minimizing moisture content and U-values are common goals for envelope design, discovering that the two objectives are inversely related through the optimization studies was significant. This outcome demonstrates how the methodology of the dissertation can be used as a framework to evaluate envelope performance to include uncertainty and degradation for multi-objective optimization and should help inform the envelope design process.
