Roofs are the single enclosure element common to artificial shelters constructed by all cultures in all climate regions. The hygrothermal performance of insulated, sloped, wood-framed roof assemblies has long been of interest to building scientists and building codes alike. Requirements for the ventilation of roof assemblies have been included in building codes for more than 50 years, however moisture problems still occur. Unvented roof assemblies have been suggested as an alternate and potentially superior solution. While unvented roofs have become relatively common in the warmer southern climates of North America, some technical issues remain unclear and the need exists for further study and demonstration of the hygrothermal performance of both ventilated and unvented roof assemblies in cold northern climates. This thesis seeks to address these issues through a review of existing literature, experience and industry practice, field investigation and measurement, analytical calculation and computer simulations.

Wood is a highly versatile renewable material (with carbon sequestering properties), that is light in weight, has good strength properties in both tension and compression while providing good rigidity and toughness, and good insulating properties (relative to typical structural materials). Engineered wood products combine the benefits of wood with engineering knowledge to create optimized structural elements. Cross-laminated timber (CLT), as one such engineered wood product, is an emerging engineering material which provides great opportunities for the building industry. While building with wood has many benefits, there are also some concerns, particularly decay. Should wood be exposed to elevated amounts of moisture, rots and moulds may damage the product or even risk the health of the occupants. As CLT panels are a relatively new engineered wood product, the moisture characteristics have yet to be properly assessed. Consequently, the amount of decay risk for CLT in building applications is unknown, and recommended protective actions during design construction and operation have yet to be determined. The goal of this research was to determine the moisture durability of CLT panels in wall assemblies and address concerns related to built-in construction moisture. The approach used to address the problem was to first determine select moisture properties of CLT panels through experimental approaches, and then use the results to calibrate a hygrothermal model to quantify the risks of wall assemblies. The wall assemblies were simulated in six different cities across Canada, representing a range of climates: Vancouver, B.C., Edmonton, A.B., Winnipeg, M.B., Ottawa, O.N., Québec City, Q.C., and St. John, New-Brunswick. The risks associated with moisture exposure during construction are also considered in the simulations. The experimental phase of the research was limited to moisture uptake tests. These tests were utilized to determine the liquid water absorption coefficient for four different types of full scale panels (2’x2’) and 12 clear wood samples. The panels were either made of 5-ply of Western-SPF, Eastern-SPF, Hemlock-Fir, or 3-ply of a generic softwood provided by a European CLT manufacturer; the clear samples were all cut from the same nominal 2x6 SPF-grade lumber. The panels were installed in a drying rack and gravimetrically tracked to assess the drying rates of the panels. Finite resources precluded more thorough material testing, but a parametric study was conducted to determine the relative impact of the missing material data on the final simulation results. In the hygrothermal simulations, four main wall assembly types were considered- those with either exterior or interior insulation, and those using either vapour permeable or impermeable air-water barriers. Various types of insulation and vapour control were also modelled. The simulations were run for a variety of interior relative humidities. The metric for comparison between the simulations was the water content of a 4mm thin layer on the extreme lamina of a CLT panel system. The results of the simulation suggest that vapour impermeable membranes, when install on dry CLT panels (less than 14% M.C.) do not pose moisture risks in any of the climates considered. However, when high levels of construction moisture is considered, only vapour permeable membranes controlled moisture risks by allowing the CLT panel to dry both to the interior and to the exterior.

This work begins by establishing the necessary and sufficient conditions for hygrothermal stability of composite laminates. An investigation is performed into the range of coupling achievable from within all hygrothermally stable families. The minimum number of plies required to create an asymmetric hygrothermally stable stacking sequence is found to be five. Next, a rigorous and general approach for determining designs corresponding to optimal levels of coupling is established through the use of a constrained optimization procedure. Couplings investigated include extension-twist, bend-twist, extension-bend, shear-twist, and anticlastic. For extension-twist and bend-twist coupling, specimens from five- through ten-ply laminates are manufactured and tested to demonstrate hygrothermal stability and achievable levels of coupling. Nonlinear models and finite element analysis are developed, and predictions are verified through comparison with test results. Sensitivity analyses are performed to demonstrate the robustness of the hygrothermal stability and couplings to deviations in ply angle, typical of manufacturing tolerances. Comparisons are made with current state-of-the-art suboptimal layups, and significant increases in coupling over previously known levels are demonstrated.

As energy certification programs and mandatory governmental building codes demand better building energy performance, the development of durable, highly insulated wall systems has become a top priority. Wood framed walls are the most common form of residential wall in North America and the materials used are vulnerable to moisture damage. This damage typically occurs first at the wall sheathing in the form of mould, fungal growth and rot. Increased thermal resistance can lead to two potential issues related to moisture durability: 1) increased potential for air leakage condensation at the sheathing and 2) decreased ability of the wall to dry after a wetting event. A natural exposure experimental study was performed at the University of Waterloo’s BEGHUT test facility to evaluate the hygrothermal performance of exterior insulated wall systems utilizing 3 different insulation types. These walls had approximately 2/3 of their total thermal resistance interior to the sheathing and 1/3 exterior to the sheathing. These walls were compared to a standard construction wall and a highly insulated double stud wall system. The test walls were evaluated during as-built conditions and during imposed wetting conditions. Moisture was introduced into the walls in two phases. The air injection wetting phase was designed to evaluate air leakage condensation potential during winter conditions, and the wetting mat wetting phase simulated an exterior rain leak and was used to evaluate the drying potential of the test walls. Hourly temperature, relative humidity and moisture content measurements were taken at multiple locations within each test wall. This data was analyzed to determine the air leakage condensation potential and the drying capability of each test wall. Results showed that the effective thermal resistance of the polyisocyanurate (PIC) insulation was significantly less than its nominal R-value rating under cold and moderate temperature conditions, and slightly higher under hot conditions. The effective thermal resistance of the extruded polystyrene (XPS) insulation was slightly less than its rated value under cold and moderate temperature conditions and significantly less under hot conditions. The rockwool (RW) insulation performed slightly above its rated thermal resistance under cold and moderate conditions and slightly less under hot conditions. Results also showed that only the double stud wall was vulnerable to winter-time interstitial condensation during the as-built (air-sealed) condition. This was a result of the hygroscopic nature of the cellulose insulation and a large temperature gradient across the insulation cavity. During the air leakage wetting phase, all of the exterior insulated walls showed a significantly decreased risk of air leakage condensation compared to the Datum and Double stud walls. During and following the wetting mat wetting phase, the PIC and XPS walls showed significantly reduced drying capability, while the RW wall showed a small reduction in drying capacity compared to the Datum and Double stud walls. It was concluded that adding insulation exterior to the wall sheathing can be an effective method to minimize air leakage condensation. The minimum ratio of exterior to interior insulation, however, must be suitable for the local climate and interior humidity conditions. Exterior insulation materials with low vapour permeability can significantly reduce the drying capacity of a wall system, but may be appropriate where exterior solar vapour drive is a concern or sufficient drying to the interior is available. Exterior insulation materials with high vapour permeability facilitate drying to the exterior and dry nearly as well as wall systems with no exterior insulation.

Wood is a highly versatile renewable material (with carbon sequestering properties), that is light in weight, has good strength properties in both tension and compression while providing good rigidity and toughness, and good insulating properties (relative to typical structural materials). Engineered wood products combine the benefits of wood with engineering knowledge to create optimized structural elements. Cross-laminated timber (CLT), as one such engineered wood product, is an emerging engineering material which provides great opportunities for the building industry. While building with wood has many benefits, there are also some concerns, particularly decay. Should wood be exposed to elevated amounts of moisture, rots and moulds may damage the product or even risk the health of the occupants. As CLT panels are a relatively new engineered wood product, the moisture characteristics have yet to be properly assessed. Consequently, the amount of decay risk for CLT in building applications is unknown, and recommended protective actions during design construction and operation have yet to be determined. The goal of this research was to determine the moisture durability of CLT panels in wall assemblies and address concerns related to built-in construction moisture. The approach used to address the problem was to first determine select moisture properties of CLT panels through experimental approaches, and then use the results to calibrate a hygrothermal model to quantify the risks of wall assemblies. The wall assemblies were simulated in six different cities across Canada, representing a range of climates: Vancouver, B.C., Edmonton, A.B., Winnipeg, M.B., Ottawa, O.N., Québec City, Q.C., and St. John, New-Brunswick. The risks associated with moisture exposure during construction are also considered in the simulations. The experimental phase of the research was limited to moisture uptake tests. These tests were utilized to determine the liquid water absorption coefficient for four different types of full scale panels (2’x2’) and 12 clear wood samples. The panels were either made of 5-ply of Western-SPF, Eastern-SPF, Hemlock-Fir, or 3-ply of a generic softwood provided by a European CLT manufacturer; the clear samples were all cut from the same nominal 2x6 SPF-grade lumber. The panels were installed in a drying rack and gravimetrically tracked to assess the drying rates of the panels. Finite resources precluded more thorough material testing, but a parametric study was conducted to determine the relative impact of the missing material data on the final simulation results. In the hygrothermal simulations, four main wall assembly types were considered- those with either exterior or interior insulation, and those using either vapour permeable or impermeable air-water barriers. Various types of insulation and vapour control were also modelled. The simulations were run for a variety of interior relative humidities. The metric for comparison between the simulations was the water content of a 4mm thin layer on the extreme lamina of a CLT panel system. The results of the simulation suggest that vapour impermeable membranes, when install on dry CLT panels (less than 14% M.C.) do not pose moisture risks in any of the climates considered. However, when high levels of construction moisture is considered, only vapour permeable membranes controlled moisture risks by allowing the CLT panel to dry both to the interior and to the exterior.

In the paper, there are presented issues related to the ice rink venues. These widely known objects,all around the world,are one of the most complex types of the public buildings. It is caused mainly by the thermal conditions, which prevails in such objects but also energy demand needed for operational processes. Range of indoor temperatures may vary from -5oC in place of ice pad and close to it, up to +20oC in dressing rooms, offices or tribunes for the spectators. Like any other buildings, the same ice rink venues should meet the conditions and provide proper indoor environmental quality (IEQ) for every user of the object. It is mainly performed by the appliance of the newest technology, which is taking care and control aspects like: temperature, relative humidity, energy usage, lighting etc. In this document, there are presented 5 ice rink facilities,which were taken into account, in order to check if there are providing comfortable and proper conditions indoors. All the investigated halls were in the City of Stockholm. In order to obtain require data, some professional tools were used including infrared camera and moisture meter. The registered data was including the average temperature of the indoor air and level of relative humidity. Based on this data, the dew point temperature has been calculated. Another aspect of the work was carrying out simulations of the typical ice rink wall construction and finding the best possible placement for the vapour barrier. In these case, the simulation had been performed in the different cities located in Sweden. Function of this layer is mainly to inhibit the migration of the water vapor and to protect the thermal insulation layer from dampness. However, installed in wrong place in the wall composition may give rise to serious problems related to moisture and humidity. By using WUFI software, it was possible to present hygrothermal conditions like: relative humidity, dew point temperature and water content of the individual component of designed wallin relation to different placement of damp proofing material.

Thermal improvement of traditional and historic buildings is going to play a crucial role in the achievement of established carbon emission targets. The suitable retrofit options for traditional buildings are, however, very limited and their long term performance is still uncertain. Evaluation of risks, prior to any alteration of building physics, is critical to avoid future damage to the fabric or occupants’ health. Moisture dynamics in building envelopes are affected by the enclosure’s geometry, materials properties and external and internal boundary conditions. Since the internal boundary is heavily influenced by users, understanding their behaviour is essential to predict the outcome of energy retrofit measures more accurately. The effect of user behaviour on energy demand has been extensively investigated; however, its impact on the hygrothermal performance of the envelopes has barely been explored. This research approached the connection between users and buildings from a new angle looking at the effect that user behaviour has on moisture dynamics of buildings’ envelopes after the retrofit. Qualitative and quantitative research methods were used to develop a holistic evaluation of the question. Firstly, factors influencing the adoption of energy efficiency measures in traditional buildings were explored by means of semi-structured interviews with private owners and project managers. Subsequently, a multi-case study including interviews with occupants and monitoring of environmental conditions was conducted. Data collected at this stage was used to explore users’ daily practices of comfort and to characterise the internal climate of traditional dwellings. Lastly, users’ impact was quantified using Heat, Air and Moisture (HAM) numerical simulation. This allowed for the evaluation of the hygrothermal performance of walls under different internal climate scenarios. Combined results of interviews, environmental monitoring and simulation showed that internal climate can compromise envelope performance after the retrofit and highlighted the need to consider users in the decision making process. Ultimately, the results of this research will help to increase awareness about the potential impact of user behaviour and provide recommendations to decision makers involved in the energy retrofit of traditional structures.

Les composites sont devenus des matériaux courants dans l’industrie dès lors que la performance est recherchée. Les matrices polymères renforcées de fibres de verre ou de carbone sont utilisées dans l’aéronautique, l’automobile et le sport pour leurs propriétés spécifiques très élevées. Depuis peu, les fibres naturelles sont envisagées comme renforts pour les matériaux polymères pour concilier performance et écologie. Cependant, l’utilisation de pièces structurales utilisant des fibres végétales se heurte à un inconvénient majeur : leur vieillissement rapide causé par une forte sensibilité à l’humidité. Dans ce mémoire, nous avons cherché à estimer la durée de vie de ces composites à travers une caractérisation de l’endommagement en atmosphère humide du matériau, et une modélisation de son absorption d’humidité. Parmi les différentes fibres végétales disponibles, le lin a été choisi pour renforcer une matrice acrylique de la gamme « Elium ». Cette acrylique de nouvelle génération est un thermoplastique dont la polymérisation peut s’effectuer à froid par ajout d’un catalyseur au même titre que la plupart des thermodurcissables, et permet donc une bonne imprégnation des fibres, et évite tout endommagement thermique des fibres de lin. L’impact du vieillissement hygrothermique du composite sur ses propriétés mécaniques a été étudié en sollicitant le matériau à des cycles d’humidité. Ce protocole a permis de différencier deux effets du vieillissement : la plastification du composite causée par la présence de molécules entre les chaînes polymériques, et l’endommagement de la structure par fragilisation de l’interface fibre/matrice et l’oxydation de la cellulose. Le premier effet est réversible par séchage alors que le second est permanent, et est le plus dommageable pour la structure. Une loi de comportement hydromécanique a pu être déduite de ces essais, et sera utilisée en parallèle d’un modèle de diffusion par éléments finis afin de déterminer l’évolution à long terme des propriétés du composite soumis à un environnement réel. Le modèle prédit une baisse de plus de 50% du module élastique, et 60% de la contrainte à rupture après un temps d’utilisation de seulement un an. Néanmoins, le modèle utilisé se base sur de nombreuses hypothèses, notamment concernant la sensibilité de l’endommagement hydrique à la température. Une étude complémentaire est donc nécessaire afin de définir une réelle durée de vie de ces matériaux / Today, when high performance is required, composite materials are a common solution. Glass fibers or carbon fibers reinforced polymers are mostly used in aeronautic, automotive and sport industries where specific properties are needed. Recently, natural fibers have been considered as a reinforcement for polymers in order to conciliate performance and ecology. However, the production of structural parts with natural fibers face a major drawback: their fast aging caused by a high water sensitivity. In this thesis, we tried to estimate their lifetime through the characterization of the composite water damaging and the modeling of the moisture absorption. Among all the natural fibers available, flax was chosen to reinforce an acrylic matrix from the range Elium®. This new generation acrylic is a thermoplastic whose polymerization can be carried out at room temperature by adding a catalyst, like thermoset polymer are commonly produced. It allows a good fiber impregnation and avoid any thermal damage of the flax fibers during the process. The effect of the hydrothermal aging of the composite on its mechanical properties has been studied by exposing the material to moisture cycles. This protocol allowed us to distinguish two several aging effects: the composite yielding induced by the presence of water molecules into the polymer network and the structure’s damage by weakening the fiber/matrix interface and oxidizing the cellulose. The first effect is reversible by drying the composite, while the second one cause permanent decrease of mechanical properties. An hydromechanical model has been determined from these experiments and has been used with a finite element model of diffusion in order to determine the long-term evolution of the composite’s mechanical properties submitted to a reel environment. The model predicts more than 50% decrease of the composite’s stiffness, and more than 60% decrease of its strength after only one year of use. Therefore, without a proper treatment of the flax fiber for purpose of limiting its water damage, the flax/acrylic composite cannot be used as a structural part

Recentemente foram aprovadas normas para requisitos e critérios de desempenho térmico de habitações de interesse social. Estas normas são importantes para a melhoria do desempenho térmico dessas habitações no Brasil. No entanto, a abordagem adotada é geral no que diz respeito às regiões bioclimáticas brasileiras e a análise é feita para sistemas da edificação (aberturas, paredes, cobertura) isoladamente, o que pode não expressar o comportamento térmico para determinadas condições climáticas. O presente estudo apresenta uma proposta de método de avaliação de desempenho higrotérmico de habitações térreas unifamiliares de interesse social para condições climáticas de Porto Alegre, RS, que visa à avaliação global da edificação através de requisitos e critérios que complementam aqueles propostos pelas normas e que sejam de fácil aplicação pelos envolvidos no processo de produção de habitações de interesse social. Considera-se a possibilidade de condensação sobre superfícies internas da edificação, coeficientes volumétricos globais de perda e ganho de calor através de sua envolvente, inércia térmica, entre outros, obtidos da literatura e da análise de quatro habitações construídas em Porto Alegre, duas submetidas a medições in loco e duas consideradas como referência para habitação de interesse social para as condições econômicas e culturais do público-alvo, segundo agentes ligados ao setor em Porto Alegre. O método foi submetido à opinião de agentes, envolvidos com o financiamento, projeto, execução, fiscalização e avaliação de habitações de interesse social em Porto Alegre, e a especialistas da área de conforto térmico atuando em instituições de ensino e pesquisa nacionais. São indicados três graus de qualidade que podem ser atingidos pelas habitações, de acordo com a disponibilidade de recursos para a construção da habitação. O método pode ser uma ferramenta auxiliar na tomada de decisão no processo de projeto, aprovação e avaliação de habitações de interesse social pelos agentes públicos ligados ao setor. / Recently, low cost housing thermal performance standards were developed and approved in Brazil. These standards establish requirements and criteria that low cost housing must satisfy. However, the approach used generally deals with climatic conditions and the evaluation is based on analysis of individual components. This approach cannot express the real thermal behaviour of housing. This study presents a thermal performance evaluation method for low cost single-family one-floor housing considering the climatic conditions of Porto Alegre, Brazil. The method aims toward a global evaluation of housing through requirements and criteria that complement the standards approved recently and it considers mathematical procedures that can be easily applied by government agents involved in this task. Inner surface condensation, global flow heat coefficients, thermal inertia, among others, obtained from literature, are proposed. Four low cost houses built in Porto Alegre, considered to be references according to social and economic local reality, were evaluated through the method. Government agents involved in the project, design, financing, building, overseeing and evaluation of low cost housing in Porto Alegre and experts from research institutes in Brazil also gave their opinions of the method. Three degrees of performance for housing, in accordance with availability of government resources, are defined. The method can be used as an evaluation of possible solutions, thereby aiding decision makers.

Recentemente foram aprovadas normas para requisitos e critérios de desempenho térmico de habitações de interesse social. Estas normas são importantes para a melhoria do desempenho térmico dessas habitações no Brasil. No entanto, a abordagem adotada é geral no que diz respeito às regiões bioclimáticas brasileiras e a análise é feita para sistemas da edificação (aberturas, paredes, cobertura) isoladamente, o que pode não expressar o comportamento térmico para determinadas condições climáticas. O presente estudo apresenta uma proposta de método de avaliação de desempenho higrotérmico de habitações térreas unifamiliares de interesse social para condições climáticas de Porto Alegre, RS, que visa à avaliação global da edificação através de requisitos e critérios que complementam aqueles propostos pelas normas e que sejam de fácil aplicação pelos envolvidos no processo de produção de habitações de interesse social. Considera-se a possibilidade de condensação sobre superfícies internas da edificação, coeficientes volumétricos globais de perda e ganho de calor através de sua envolvente, inércia térmica, entre outros, obtidos da literatura e da análise de quatro habitações construídas em Porto Alegre, duas submetidas a medições in loco e duas consideradas como referência para habitação de interesse social para as condições econômicas e culturais do público-alvo, segundo agentes ligados ao setor em Porto Alegre. O método foi submetido à opinião de agentes, envolvidos com o financiamento, projeto, execução, fiscalização e avaliação de habitações de interesse social em Porto Alegre, e a especialistas da área de conforto térmico atuando em instituições de ensino e pesquisa nacionais. São indicados três graus de qualidade que podem ser atingidos pelas habitações, de acordo com a disponibilidade de recursos para a construção da habitação. O método pode ser uma ferramenta auxiliar na tomada de decisão no processo de projeto, aprovação e avaliação de habitações de interesse social pelos agentes públicos ligados ao setor. / Recently, low cost housing thermal performance standards were developed and approved in Brazil. These standards establish requirements and criteria that low cost housing must satisfy. However, the approach used generally deals with climatic conditions and the evaluation is based on analysis of individual components. This approach cannot express the real thermal behaviour of housing. This study presents a thermal performance evaluation method for low cost single-family one-floor housing considering the climatic conditions of Porto Alegre, Brazil. The method aims toward a global evaluation of housing through requirements and criteria that complement the standards approved recently and it considers mathematical procedures that can be easily applied by government agents involved in this task. Inner surface condensation, global flow heat coefficients, thermal inertia, among others, obtained from literature, are proposed. Four low cost houses built in Porto Alegre, considered to be references according to social and economic local reality, were evaluated through the method. Government agents involved in the project, design, financing, building, overseeing and evaluation of low cost housing in Porto Alegre and experts from research institutes in Brazil also gave their opinions of the method. Three degrees of performance for housing, in accordance with availability of government resources, are defined. The method can be used as an evaluation of possible solutions, thereby aiding decision makers.