The Intergovernmental Panel on Climate Change (IPCC) estimates that buildings account for 40% of the global energy use. The IPCC believes substantial improvements to building efficiency can be implemented easily by improving building enclosures through increased levels of insulation, optimizing glazing areas and minimizing infiltration of outside air.<br><br> Building enclosure design encompasses a wide range of parameters but the transport of heat, air and moisture through the enclosure is of primary importance. In predominantly cold Canadian climates, adequate thermal insulation, effective air barriers, and proper moisture control are crucial for energy savings and durability of the structure.<br><br> For decades, standard construction practice in Canada dictated a polyethylene sheet behind the interior drywall layer to serve as a vapour barrier for assemblies with traditional fibre-based cavity insulation. If the polyethylene sheet was sealed carefully enough it had the added benefit of reducing air leakage. Unfortunately, vapour barriers place the emphasis on the wrong moisture transport mechanism; air leakage can have 10 times or greater the wetting potential than vapour diffusion. Regardless, code enforcement personnel continued (and continue in some areas) to require vapour barriers in all climates, all assemblies, and all occupancies. To do so, they overrule the provision in Part 5 of The National Building Code of Canada that states vapour barriers are not required if it can be shown that the uncontrolled vapour diffusion will not affect the operation of the building and systems, or the health and safety of the occupants.<br><br> Foam plastic insulations perform better than fibre-based insulation in terms of the combined resistance to transmission of heat, air and vapour. This research investigated several types of open cell and closed cell spray polyurethane foam insulation in a variety of assembly configurations both in lab tests and hygrothermal simulations. The simulations were extrapolated to seven Canadian climate categories and three levels of interior relative humidity. The goal was to determine which spray polyurethane foam applications required the addition of a dedicated vapour barrier layer beyond what the foam itself could provide.<br><br> The moisture content of the oriented strand board sheathing layer (OSB) in the tested and modelled assemblies was used as the performance evaluation point because during wintertime vapour drives, the wood sheathing is the most likely condensing surface. Prolonged high moisture content (greater than 20%) in wood and wood products in wall assemblies leads to mould growth and decay. By this measure, if the wood sheathing moisture contents stay within the safe range (less than 19%) a vapour barrier is not necessary. The results are presented in Table 7-4.<br><br> The performance of assemblies containing closed cell spray foam was excellent for all climates and humidity levels. Their performance was equivalent to traditional wall assemblies incorporating a polyethylene sheet vapour barrier. The performance of assemblies with open cell spray foam was equivalent to traditional wall assemblies containing no vapour barrier. Open cell spray foam and fibreglass batt both require additional vapour control layers with all but the mildest Canadian climates with the lowest interior humidities. However, in those mild climates with low interior humidities, the only vapour control layer required was a medium permeance latex paint with primer.<br><br>

De nos jours, l'humidité dans les bâtiments est une problématique majeure car elle impacte simultanément la consommation énergétique, le confort des occupants, ainsi que les risques de moisissures dans l'envelope du bâtiment. Les matériaux de construction ont la capacité d'absorber et de libérer de grandes quantités de vapeur d'eau et peuvent par conséquent amortir les variations d'humidité relative intérieure. Cette proporiété est appelée tampon hygrique. Elle est liée aux échanges de vapeur d'eau entre l'air intérieur et les parois, à la ventilation, et aux sources de vapeur. Cet effet a été précédemment mis en évidence à l'échelle du matériau et de la paroi par des expériences de laboratoire et des modèles numériques. Cependant, peu de modèles décrivent de manière réaliste les sources intérieures dues à la présence et aux activités des occupants. Dans ce travail, un modèle hygrothermique à l'échelle de la pièce a été développé en Python afin d'investiguer l'influence du scénario d'occupation, et l'impact du tampon hygrique des parois sur l'air intérieur. Ce modèle regroupe les transferts couplés d'énergie et de masse dans les parois, ainsi que les sources intérieures décrites par un système de conditionnement d'air et par la présence et les activités des occupants. Ce dernier étant modélisé de manière stochastique par un modèle implémenté dans une plateforme nommée No-MASS. Des indicateurs de performance sur les besoins énergétiques, le confort hygrique intérieur, et les risques liés aux moisissures dans les parois ont été définis pour quantifier la performance hygrothermique d'une pièce. La sensibilité des indicateurs de performance vis-à-vis du scénario d'occupation a été évaluée en simulant des scénarios stochastique, déterministe et constant. Les résultats ont montré une influence marginale du scénario à l'échelle de l'année. [...} / Humidity in buildings has nowadays become a major concern as it impacts simultaneously the energy consumption, the occupants' comfort and the moisture related risks in the buildings envelope. Buildings materials have the ability to absorb and release large amounts of moisture and therefore they may dampen the indoor relative humidity variations. This is called the moisture buffering capacity. It depends on the vapour exchanges between the air and the walls, the ventilation and the indoor moisture sources. This property was previously highlighted at material and wall scales through laboratory experiments and numerical models. However, few models describe the indoor sources due to the occupants' presence and activities in a realistic way. In this work, a hygrothermal room model was developed in Python to investigate the influence of the occupancy scenario and of the impact of the walls moisture buffering on indoor air balance. This model regroups the coupled heat and mass transfer in the walls, as well as the indoor sources depicted by the air-conditioning system and the occupants' presence and activities. The numerical modelling of the latter relies on a stochastic occupancy model implemented in a platform called No-MASS. Performance indicators on the energy demand, the indoor hygric comfort and the moisture related risks in the walls were defined to quantify the hygothermal performance of a room. The sensitivity of the performance indicators towards the occupancy scenario was assessed by simulating a stochastic occupancy scenario, a deterministic one and a constant one. Results showed a marginal influence of the scenario at year scale. However, at smaller time scales (seasonal or monthly), their impact on the indoor relative humidity dampening was not negligible, mainly due to the consideration of a seasonal effect for the stochastic scenario. [...]

Concilier patrimoine et amélioration de la performance énergétique du bâti ancien est un défi pour de nombreux centres historiques. La Communauté d’Agglomération du Grand Cahors, qui finance ce travail de thèse à travers une convention CIFRE, a souhaité s’attaquer à cette problématique en valorisant des isolants bio-sourcés. Le choix du matériau et du système d’isolation sont essentiels car ils influencent à la fois la performance hygrothermique de la paroi, la qualité de l’air intérieur, le coût et l’empreinte carbone de la rénovation. Dans cette étude, nous nous sommes focalisé sur la performance hygrothermique de la paroi afin d’assurer que la mise en place d’une isolation par l’intérieur ne soit pas source de dégradations futures de la paroi. Pour cela, nous avons confronté différents outils et méthodes tels que la caractérisation physique des matériaux, une instrumentation in-situ dans deux appartements du centre ancien de Cahors et des simulations hygrothermiques alliant différents outils numériques. / Improving the energy efficiency of buildings is essential to reduce greenhouse gas emissions and mitigate against climate change. Historic dwellings represent a large part of the French building stock that needs to be refurbished. In the city center of Cahors, France, the old medieval dwellings are considered as valuable cultural heritage and internal insulation is often the only insulation technique that can be used when the architectural value of the exterior façade is to be preserved. This PhD thesis, funded by a CIFRE agreement with the Communauté d’Agglomération du Grand Cahors, studied the suitability of bio-based materials for the internal insulation of historical dwellings in urban area. The selection of the insulation material and the system is crucial because of its impact on the hygrothermal performance of the wall, the indoor air quality, the financial cost, and the carbon footprint of the refurbishment solution. In this study we focused on the hygrothermal performance of the walls to provide a reliable risk assessment in order to avoid hygrothermal failure. Due to the complexity of the problem and the lack of needed data, we ran a multi-scale study including both experimental (laboratory characterisation and building monitoring) and numerical modelling methods.

La réduction de la consommation énergétique dans le secteur de bâtiments présente aujourd’hui une priorité primordiale dans les politiques des pays industrialisés. En France, le secteur du bâtiment consomme environ 43 % de l’énergie finale et contribue pour près d’un quart aux émissions nationales de gaz à effet de serre [ADEME]. Il se positionne comme un acteur clé pour parvenir à résoudre les inquiétants défis environnementaux auxquels nous devons faire face. Face à ces véritables défis, l’augmentation des niveaux d’exigence des réglementations thermiques s’est poursuivie et intensifiée pendant les 40 dernières années, jusqu’à la naissance de la réglementation thermique 2012, qui a permis de construire des bâtiments basse consommation (BBC) qui équivaut à 50 kWh/m².an. Cette nouvelle réglementation plus exigeante constitue une incitation forte à l'innovation des matériaux, produits et systèmes d'enveloppe. Dans ces conditions, l’amélioration des performances hygrothermiques des matériaux de construction aura des retombées économiques et environnementales conséquentes. C’est dans ce contexte que ce travail a été mené. Il vise à étudier et à améliorer les performances des produits de l’entreprise Briqueteries du Nord (BdN). Il est réparti sur deux axes principaux : le premier consiste à l’étude de l’inertie thermique et du pouvoir hygroscopique des briques en terre crue. Le second axe vise à élaborer des solutions possibles concernant l’amélioration de la résistance thermique des briques en terre cuite. Ce travail de recherche a été réalisé au laboratoire de l’Ecole Centrale de Lille avec une étroite collaboration avec l’université d’Artois et l’entreprise (BdN) / Nowadays, the reduction of energy consumption in buildings industry represents a major issue in industrialized countries’ policies. In France, the building sector consumes about 43% of final energy and accounts for nearly a quarter of the national emissions of greenhouse gas emissions [ADEME]. It is considered as a key factor to overcome the environmental challenges we have to face.In front of these significant challenges, the thermal regulations requirements were seriously intensified during the last 40 years until the notification of the thermal regulation 2012. This latter enable the construction of low energy buildings (BBC) whose consumption is equivalent to 50 kWh/m² per year on average. This new regulation provides a strong incentive for innovation of materials, products and envelope systems. Under these conditions, improving hygrothermal performance of building materials will allow a substantial economic and environmental benefits. This work was conducted in this context. It aims to study and improve the performance of the company Briqueteries du Nord (BdN) products. It is divided in two main axis: the first consists on studying the thermal inertia and hygroscopic capacity of unfired clay bricks. However, the second axis aims to develop possible solutions for improving the thermal resistance of fired clay bricks. This research was conducted in the laboratory of the Ecole Centrale de Lille with close collaboration with the University of Artois and the BdN company

The main aim of the thesis was focused on hygrothermal simulation of critical details of two prefabricated wooden buildings - especially connections of the perimeter wall to monolithic foundations, respectively with waterproofing layer. The composition of the external walls of these selected buildings has quite different compositions and thus different potentials of drying integrated moisture from the components. Practical measurement of moisture weight-content was applied to the wooden bottom plate, which is in direct contact with the concrete slab structures. The influence of different design solutions on hygrothermal characteristics of the wooden plate was examined with regards to the risk of mould growth, analysis of mass loss due to the decay fungi and with the aim to estimate the durability of the studied details of prefabricated wooden houses. The subsequent research focused on the differences in physical and mechanical properties of natural spruce wood (Untreated, (-), A) and impregnated spruce (Treated, (+), B) using supercritical CO2 and its possible impact on wood protection for mould growth. Samples of identical Untreated and Treated spruce were collected in the laboratory and subjected to thermal and hygrothermal experiments. The comparison of the resulting values of the individual experiments is presented. Required values needed for numerical calculations were obtained from these experiments. In conclusion, the summary of founded comparison is presented. The mould growth analysis and its influence on the durability of wooden structures offer a view of the behaviour of the structures. Relevant findings and recommendations for the future praxis are mentioned.