Construction combustible
La sécurité incendie dans un bâtiment est une question complexe, bien plus complexe que la combustibilité relative des principaux matériaux structurels utilisés dans un bâtiment. Pour élaborer des dispositions de code sûres, la prévention, l'extinction, le déplacement des occupants, la mobilité des occupants, l'utilisation du bâtiment et le contrôle des combustibles ne sont que quelques-uns des facteurs qui doivent être pris en compte en plus de la combustibilité des éléments structurels. L'expérience des pertes dues aux incendies montre que le contenu des bâtiments joue un rôle important en termes de charge de combustible et de potentiel de génération de fumée dans un incendie. La protection passive contre l'incendie assurée par les degrés de résistance au feu des planchers et des murs d'un bâtiment garantit la stabilité de la structure en cas d'incendie. Cependant, le degré de résistance au feu des structures ne contrôle pas nécessairement le mouvement des fumées et de la chaleur, qui peut avoir un impact important sur le niveau de sécurité et les dommages matériels résultant d'un incendie. Le Code national du bâtiment du Canada (CNB) classe les bâtiments en bois dans la catégorie des "constructions combustibles". Bien qu'elles soient qualifiées de combustibles, les techniques de construction courantes peuvent conférer aux constructions à ossature en bois des degrés de résistance au feu allant jusqu'à deux heures. Lorsqu'ils sont conçus et construits conformément aux exigences du code, les bâtiments en bois offrent le même niveau de sécurité des personnes et de protection des biens que les bâtiments de taille comparable définis par le CNB comme des "constructions non combustibles". Le bois a été utilisé pour pratiquement tous les types de bâtiments, y compris les écoles, les entrepôts, les casernes de pompiers, les immeubles d'habitation et les installations de recherche. Le CNB définit des lignes directrices pour l'utilisation du bois dans des applications qui vont bien au-delà du secteur résidentiel traditionnel et des petits bâtiments. Le CNB autorise les constructions en bois d'une hauteur maximale de six étages, ainsi que les bardages en bois pour les bâtiments désignés comme étant de construction incombustible. Lorsqu'elle respecte les limites de surface et de hauteur pour les différentes catégories de bâtiments du CNB, la construction à ossature bois peut répondre aux exigences de sécurité des personnes en utilisant des assemblages à ossature bois (généralement protégés par des plaques de plâtre) dont le degré de résistance au feu a été testé. Les restrictions de hauteur et de surface autorisées peuvent être étendues en utilisant des murs coupe-feu pour diviser une grande surface de bâtiment en plus petites surfaces distinctes. La contribution positive reconnue à la fois à la sécurité des personnes et à la protection des biens qui découle de l'utilisation de systèmes d'extinction automatique peut également être utilisée pour augmenter la surface autorisée des bâtiments en bois. Les sprinkleurs interviennent généralement très tôt dans un incendie, ce qui permet d'en contrôler rapidement les effets dommageables. C'est pourquoi l'installation d'un système d'extinction automatique dans un bâtiment améliore considérablement la sécurité des personnes et la protection des biens dans tous les bâtiments, y compris ceux construits en matériaux incombustibles. Le CNB autorise l'utilisation d'une "construction en bois massif" dans les bâtiments où la construction combustible doit avoir un degré de résistance au feu de 45 minutes. Cette forme de construction en bois massif est également autorisée dans les grands bâtiments incombustibles de certains usages. Pour être acceptés, les éléments doivent répondre à des exigences minimales en matière de dimensions et d'installation. La construction en bois massif bénéficie de cette reconnaissance en raison de ses performances en cas d'exposition réelle au feu et de son acceptation en tant que méthode de construction sûre en cas d'incendie. Dans les bâtiments protégés par sprinklers dont la construction est autorisée à être combustible, aucun degré de résistance au feu n'est requis pour la toiture ou ses supports lorsqu'ils sont construits en bois massif. Dans ce cas, la toiture en bois massif et ses supports n'ont pas à respecter les dimensions minimales des éléments stipulées dans le CNB. Les éléments en bois massif peuvent également être utilisés chaque fois qu'une construction combustible est autorisée. Dans ce cas, cependant, ces éléments en bois massif doivent être spécifiquement conçus pour satisfaire aux degrés de résistance au feu requis. Définitions du CNB : Combustible signifie qu'un matériau ne répond pas aux critères d'acceptation de la norme CAN/ULC-S114, "Essai de détermination de l'incombustibilité des matériaux de construction". On entend par construction combustible le type de construction qui ne répond pas aux exigences de la construction incombustible. Construction en bois lourd : ce type de construction combustible dans laquelle un certain degré de sécurité incendie est atteint en limitant les dimensions des éléments structurels en bois ainsi que l'épaisseur et la composition des planchers et des toits en bois, et en évitant les espaces cachés sous les planchers et les toits. Construction incombustible : type de construction dans lequel un degré de sécurité incendie est atteint par l'utilisation de matériaux incombustibles pour les éléments de structure et autres assemblages de bâtiments. Incombustible signifie qu'un matériau répond aux critères d'acceptation de la norme CAN/ULC-S114, "Essai de détermination de l'incombustibilité des matériaux de construction". Pour de plus amples informations, veuillez consulter les ressources suivantes : Code national du bâtiment du Canada CAN/ULC-S114 Essai de détermination de l'incombustibilité des matériaux de construction Manuel de conception en bois 2017
Construction en bois massif encapsulé
In addition to combustible, heavy timber and noncombustible construction, a new construction type is presently being considered for inclusion into the National Building Code of Canada (NBC). Encapsulated mass timber construction (EMTC) is proposed to be defined as the “type of construction in which a degree of fire safety is attained by the use of encapsulated mass timber elements with an encapsulation rating and minimum dimensions for the structural timber members and other building assemblies.” EMTC is neither ‘combustible construction’ nor ‘heavy timber construction’ nor ‘noncombustible construction’, as defined within the NBC. EMTC is required to have an encapsulation rating. The encapsulation rating is the time, in minutes, that a material or assembly of materials will delay the ignition and combustion of encapsulated mass timber elements when it is exposed to fire under specified conditions of test and performance criteria, or as otherwise prescribed by the NBC. The encapsulation rating for EMTC is determined through the ULC S146 test method. In order for structural wood elements to be considered ‘mass timber’, they must meet minimum size requirements, which are different for horizontal (walls, floors, roofs, beams) and vertical (columns, arches) load-bearing elements and dependent on the number of sides that the element is exposed to fire. EMTC construction in Canada is expected to be limited to a height of twelve-storeys, that is, the uppermost floor level may be a maximum of 42 m (137 ft) above the first floor. An EMTC building must be sprinklered throughout according to NFPA 13 and it is likely that some mass timber will also be able to be exposed in the suites. All EMTC elements are expected to have a minimum two-hour fire resistance rating and the building floor area to be limited to 6,000 m2 for Group C occupancy and 7,200 m2 for Group D occupancy. There are restrictions on the use of exterior cladding elements in EMTC, as well as other restrictions on the use of; combustible roofing materials, combustible window sashes and frames, combustible components in exterior walls, nailing elements, combustible flooring elements, combustible stairs, combustible interior finishes, combustible elements in partitions, and concealed spaces. If any encapsulation material is damaged or removed, it will be required to be repaired or replaced so that the encapsulation rating of the materials is maintained. Additionally, requirements related to construction site fire safety are to be applied to construction access, standpipe installation and protective encapsulation. EMTC and its related provisions are anticipated to be included in the NBC 2020. NBC definitions: Combustible means that a material fails to meet the acceptance criteria of CAN/ULC-S114, “Test for Determination of Non-Combustibility in Building Materials.” Combustible construction means that type of construction that does not meet the requirements for noncombustible construction. Heavy timber construction means that type of combustible construction in which a degree of fire safety is attained by placing limitations on the sizes of wood structural members and on thickness and composition of wood floors and roofs and by the avoidance of concealed spaces under floors and roofs. Noncombustible construction means that type of construction in which a degree of fire safety is attained by the use of noncombustible materials for structural members and other building assemblies. Noncombustible means that a material meets the acceptance criteria of CAN/ULC-S114, “Test for Determination of Non-Combustibility in Building Materials.” For further information, refer to the following resources: Guide to Encapsulated Mass Timber Construction in the Ontario Building Code ULC S146 Standard Method of Test for the Evaluation of Encapsulation Materials and Assemblies of Materials for the Protection of Mass Timber Structural Members and Assemblies Fire performance of mass-timber encapsulation methods and the effect of encapsulation on char rate of cross-laminated timber (Hasburgh et al., 2016) CAN/ULC-S114 Test for Determination of Non-Combustibility in Building Materials NFPA 13 Standard for the Installation of Sprinkler Systems
Grands bâtiments en bois
With advanced construction technologies and modern mass timber products such as glued-laminated timber, cross-laminated timber and structural composite lumber, building tall with wood is not only achievable but already underway – with completed contemporary buildings in Australia, Austria, Switzerland, Germany, Norway and the United Kingdom at 9 storeys and taller. Increasingly recognized by the construction sector as an important, new, and safe construction choice, the reduced carbon footprint and embodied / operational energy performance of these buildings is appealing to communities that are committed to sustainable development and climate change mitigation. Tall wood buildings, built with renewable wood products from sustainably managed forests, have the potential to revolutionize a construction industry increasingly focused on being part of the solution when it comes to urban intensification and environmental impact reduction. The Canadian wood product industry is committed to building on its natural advantage, through the development and demonstration of continuously improving wood-based building products and building systems. A tall wood building is a building over six-storeys in height (top floor is higher than 18 m above grade) that utilizes mass timber elements as a functional component of its structural support system. With advanced construction technologies and modern mass timber products such as glued-laminated timber (glulam), cross-laminated timber (CLT) and structural composite lumber (SCL), building tall with wood is not only achievable but already underway – with completed contemporary buildings in Canada, US, Australia, Austria, Switzerland, Germany, Norway, Sweden, Italy and the United Kingdom at seven-storeys and taller. Tall wood buildings incorporate modern fire suppression and protection systems, along with new technologies for acoustic and thermal performance. Tall wood buildings are commonly employed for residential, commercial and institutional occupancies. Mass timber offers advantages such as improved dimensional stability and better fire performance during construction and occupancy. These new products are also prefabricated and offer tremendous opportunities to improve the speed of erection and quality of construction. Some significant advantages of tall wood buildings include: the ability to build higher in areas of poor soils, as the super structure and foundations are lighter compared to other building materials; quieter to build on site, which means neighbours are less likely to complain and workers are not exposed to high levels of noise; worker safety during construction can be improved with the ability to work off large mass timber floor plates; prefabricated components manufactured to tight tolerances can reduce the duration of construction; tight tolerances in the building structure and building envelope coupled with energy modelling can produce buildings with high operational energy performance, increased air tightness, better indoor air quality and improved human comfort Design criteria for tall wood buildings that should be considered include: an integrated design, approvals and construction strategy, differential shrinkage between dissimilar materials, acoustic performance, behaviour under wind and seismic loads, fire performance (e.g., encapsulating the mass timber elements using gypsum), durability, and construction sequencing to reduce the exposure of wood to the elements. It is important to ensure early involvement by a mass timber supplier that can provide design assistance services that can further reduce manufacturing costs through the optimization of the entire building system and not just individual elements. Even small contributions, in connection designs for example, can make a difference to the speed of erection and overall cost. In addition, mechanical and electrical trades should be invited in a design-assist role at the outset of the project. This allows for a more complete virtual model, additional prefabrication opportunities and quicker installation. Recent case studies of modern tall wood buildings in Canada and around the world showcase the fact that wood is a viable solution for attaining a safe, cost-effective and high-performance tall building. For more information, refer to the following case studies and references: Brock Commons Tall Wood House (Canadian Wood Council) Origine Point-aux-Lievres Ecocondos,Quebec City (Cecobois) Wood Innovation and Design Centre (Canadian Wood Council) Technical Guide for the Design and Construction of Tall Wood Buildings in Canada (FPInnovations) Ontario’s Tall Wood Building Reference (Ministry of Natural Resources and Forestry & Ministry of Municipal Affairs) Summary Report: Survey of International Tall Wood Buildings (Forestry Innovation Investment & Binational Softwood Lumber Council) www.thinkwood.com/building-better/taller-buildings
Immeubles de moyenne hauteur
When it comes to wood construction, many people think of basic 2×4 framing, panels or flooring for single-family homes. However, advances in wood science and building technology have resulted in stronger, more sophisticated and robust products that are expanding the options for wood construction, and providing more choices for builders and architects. The Canadian Wood Council’s support for mid-rise construction is not unique In Ontario, Home Builders, through organizations such as RESCON, BILD and the Ontario Home Builders Association are also highlighting this opportunity. Mid-rise buildings made of wood are a new construction option for builders. That’s good news for main-street Canada, where land is so expensive. The net benefit of reduced construction costs is increased affordability for home buyers. In terms of new economic opportunity, the ability to move forward “now” creates new construction jobs in cities and supports employment in forestry communities. This also offers increased export opportunities for current and innovative wood products, where adoption in Canada provides the example for other countries. This also reflects a new standard of engineering in that structural, fire and seismic concerns have all been addressed by the expert committees of the Canadian Commission on Building and Fire Codes. In the end, when occupied, mid-rise buildings fully meet the same requirements of the Building Code as any other type of construction from the perspective of health, safety and accessibility.
Ponts
Timber bridges have a long history as vital components of the roadway, railway and logging road networks within Canada. Dependent on the availability of materials, technology, and labour, the design and construction of wood bridges has evolved significantly over the last 200 hundred years throughout North America. Wood bridges take on many forms and use alternative support systems; including simple span log bridges, different types of trussed bridges, and stress-laminated or composite bridge decks and components. Timber bridges remain an important part of our transportation network in Canada. The benefits of building modern timber bridges include: The different types of materials used to construct wood bridges include: sawn lumber, round logs, straight and curved glued-laminated timber (glulam), laminated veneer lumber (LVL), parallel strand lumber (PSL), cross-laminated timber (CLT), nail-laminated timber (NLT), and composite systems such as stress-laminated decks, wood-concrete laminated decks, and fibre-reinforced polymers. Two main wood species used for wood bridge construction in Canada are Douglas fir and the Spruce-Pine-Fir species combination. Other species within the Hem-Fir and Northern species combinations are also recognized under CSA O86, however, they are less commonly used in bridge construction. All metal fasteners used for bridges must be protected against corrosion. The most common method for providing protection is hot dip galvanizing, a process whereby a sacrificial metal is added to exterior of the fastener. Different fastener types that are used in wood bridge construction include, but are not limited to, bolts, lag screws, split rings, shear plates, and nails (for deck laminations only). All highway bridges in Canada must be designed to meet the requirements outlined in CSA S6 and CSA O86. The CSA S6 standard requires that the main structural components of any bridge in Canada, regardless of construction type, be able to withstand a minimum of 75 years of loading during its service life. The style and span of bridges varies greatly depending on the application. In hard to reach locations with deep valleys, timber trestle bridges were common at the end of the 19th century and into the beginning of the 20th century. Historically, trestle bridges relied heavily on ample timber resources and in some cases, were considered to be temporary. Initial construction of North America’s transcontinental railways would not have been possible without the use of timbers to construct bridges and trestles. Many examples of trussed timber bridges for have been built for well over a century. Trussed bridges allow for longer spans compared to simple girder bridges and historically had spans in the range of 30 to 60 m (100 to 200 ft). Bridges that are designed with trusses located above the deck provide a great opportunity to build a roof over the roadway. Installing a roof overhead is an excellent way to shed water away from the main bridge structure and protect it from the sun. The presence of these covered roofs is the main reason these century-old covered bridges remain in service today. The fact that they remain part of our landscape is as much a testament to their hardiness as to their attractiveness. Although originally devised as a rehabilitation measure for aging bridge decks, the stress-laminating technique has been extended to new bridges through the application of stressing at the time of original construction. Stress-laminated decks provide improved structural behaviour, through their excellent resistance to the effects of repeated loading. Three main considerations related to durability of wood bridges include protection by design, preservative treatment of wood, and replaceable elements. A bridge can be designed such that it is inherently self-protecting by deflecting water away from the structural elements. Preservative treated wood has the ability to resist the effects of de-icing chemicals and attack by biotic agents. Lastly, the bridge should be designed such that, at some point in its future, a single element can be replaced relatively easily, without significant disruption or cost. For further information, refer to the following resources: Wood Highway Bridges (Canadian Wood Council)Ontario Wood Bridge Reference Guide (Canadian Wood Council)CSA S6 Canadian Highway Bridge Design CodeCSA O86 Engineering design in wood
Grands bâtiments en bois - Recherche
Tests Current research includes the World’s largest mass timber fire test – click here for updates on the test results currently being conducted https://firetests.cwc.ca/ Studies “The Historical Development of the Building Size Limits in the National Building Code of Canada (17 Mb) “Case Studies of Risk-to-Life due to Fire in Mid- and High-Rise, Combustible and Non-combustible Buildings Using CUrisk“, by Xia Zhang and George Hadjisophocleous of Carleton University, and Jim Mehaffey of CHM Fire Consultants Ltd. (March 2015) (2.3 Mb) “Fire Safety Challenges of Tall Wood Buildings”, by Robert Gerard and David Barber – Arup North America Ltd; Armin Wolski, San Francisco, CA; for the National Fire Protection Association’s Fire Protection Research Foundation (December 2013) “The Case for Tall Wood Buildings – How Mass Timber Offers a Safe, Economical, and Environmentally Friendly Alternative for Tall Building Structures“, by mgb ARCHITECTURE + DESIGN, Equilibrium Consulting, LMDG Ltd, and BTY Group (February 2012) (8.5 Mb) Ontario Tall Wood Reference Guide (8.04 MB) Reports Fire Research Final Report – Full-scale Mass Timber Shaft Demonstration Fire (including the National Research Council test report as an Appendix), by FPInnovations (April 2015) Acoustics Research and Guides RR-331: Guide to calculating airborne sound transmission in buildings (2nd Edition), by the National Research Council (April 2016) Tall Wood Building Demonstration Initiative Test Reports (funding provided by Natural Resources Canada) CLT Diaphragm Properties CLT Firestopping Testing Monotonic Quasi-Static Testing of CLT Connections Shear Modulus of CLT in plan loading Shear Testing of Cross-Laminated Beams Full Scale Exterior Wall Test on Nordic CLT System, by the National Research Council (January 2015) Client Report A1-005991.1 – Fire Endurance of Cross-Laminated Timber Floor and Wall Assemblies for Tall Wood Buildings, by the National Research Council (December 2014) Measurement of Airborne Sound Insulation of Wall & Floor Assemblies Visit Think Wood’s Research Library for additional resources
Bâtiments de moyenne hauteur - Recherche
Studies General “The Historical Development of the Building Size Limits in the National Building Code of Canada“, by Sereca for CWC (2015) (17 Mb) Structural & Seismic Vertical Movement in Wood Platform Frame Structures (CWC Fact Sheets) Basics Design and detailing solutions Movement prediction Design of multi-storey wood-based shearwalls: Linear dynamic analysis & mechanics based approach A Mechanics-based Approach for Determining Deflections of Stacked Multi-storey Wood-based Shearwalls Design of Stacked Multi-storey Wood Shearwalls using a Mechanics Based Approach Linear Dynamic Analysis for Wood Based Shear Walls and Podium Structures Design of wood frame and podium structures using linear dynamic analysis, by Newfield, G., Ni, C., and Wang, J., Proceedings of the World Conference on Timber Engineering 2014, Quebec City, Canada (2014) Testing Other Reports Final Report – Full-scale Mass Timber Shaft Demonstration Fire (including the National Research Council test report as an Appendix), by FPInnovations (April 2015) Full Scale Exterior Wall Test on Nordic CLT System, by the National Research Council (January 2015) Report No. 101700231SAT-003_Rev.1 – Report of Testing Cross-Laminated Timber Panels for Compliance with CAN/ULC-S101 Standard Methods of Fire Endurance Tests of Building Construction and Materials: Loadbearing 3-ply CLT Wall with 1 Layer of 5/8″ Type X Gypsum Board – 1 hr FRR, by Intertek for CWC (November 2014) Report No. 100585447SAT-002B – Report of Testing Cross-Laminated Timber Panels for Compliance with CAN/ULC-S101 Standard Methods of Fire Endurance Tests of Building Construction and Materials: Loadbearing 3-ply CLT Wall with 1 Layer of 5/8″ Fire-rated Gypsum Board (60% load) – 1 hr FRR, by Intertek for CWC (December 2013) Report No. 100585447SAT-002A_Rev.1 – Report of Testing Cross-Laminated Timber Panels for Compliance with CAN/ULC-S101 Standard Methods of Fire Endurance Tests of Building Construction and Materials: Loadbearing 3-ply CLT Wall with Attached Wood-frame Partition – 1 hr FRR, by Intertek for CWC (January 2012) Visit Think Wood’s Research Library for additional resources
Vert
Le bois est le seul grand matériau de construction qui pousse naturellement et qui est renouvelable. Avec la pression croissante pour réduire l'empreinte carbone de l'environnement bâti, les concepteurs de bâtiments sont de plus en plus appelés à équilibrer les objectifs de fonction et de coût d'un bâtiment avec un impact réduit sur l'environnement. Le bois peut contribuer à cet équilibre. De nombreuses études d'évaluation du cycle de vie réalisées dans le monde entier ont montré que les produits en bois présentent des avantages environnementaux évidents par rapport à d'autres matériaux de construction, et ce à tous les stades. Les bâtiments en bois permettent de réduire les émissions de gaz à effet de serre, la pollution de l'air, les volumes de déchets solides et l'utilisation des ressources écologiques.
Efficacité énergétique
Of all the energy used in North America, it is estimated that 30 to 40 percent is consumed by buildings. In Canada, the majority of operational energy in residential buildings is provided by natural gas, fuel oil, or electricity, and is consumed for space heating. Given the fact that buildings are a significant source of energy consumption and greenhouse gas emissions in Canada, energy efficiency in the buildings sector is essential to address climate change mitigation targets. As outlined in the Pan-Canadian Framework on Clean Growth and Climate Change, the federal, provincial and territorial governments are committed to investment in initiatives to support energy efficient homes and buildings as well as energy benchmarking and labelling programs. Despite the expanding number of choices for consumers, the most cost-effective way to increase building energy performance has remained unchanged over the decades: • maximize the thermal performance of the building envelope by adding more insulation and reducing thermal bridging; and • increase the airtightness of the building envelope. The building envelope is commonly defined as the collection of components that separate conditioned space from unconditioned space (exterior air or ground). The thermal performance and airtightness of the building envelope (also known as the building enclosure) effects the whole-building energy efficiency and significantly affects the amount of heat losses and gains. Building and energy codes and standards within Canada have undergone or are currently undergoing revisions, and the minimum thermal performance requirements for wood-frame building enclosure assemblies are now more stringent. The most energy efficient buildings are made with materials that resist heat flow and are constructed with accuracy to make the best use of insulation and air barriers. To maximize energy efficiency, exterior wall and roof assemblies must be designed using framing materials that resist heat flow, and must include continuous air barriers, insulation materials, and weather barriers to prevent air leakage through the building envelope. The resistance to heat flow of building envelope assemblies depends on the characteristics of the materials used. Insulated assemblies are not usually homogeneous throughout the building envelope. In light-frame walls or roofs, the framing members occur at regular intervals, and, at these locations, there is a different rate of heat transfer than in the spaces between the framing members. The framing members reduce the thermal resistance of the overall wall or ceiling assembly. The rate of heat transfer at the location of framing elements depends on the thermal or insulating properties of the structural framing material. The higher rate of heat transfer at the location of framing members is called thermal bridging. The framing members of a wall or roof can account for 20 percent or more of the surface area of an exterior wall or roof and since the thermal performance of the overall assembly depends on the combined effect of the framing and insulation, the thermal properties of the framing materials can have a significant effect on the overall (effective) thermal resistance of the assembly. Wood is a natural thermal insulator due to the millions of tiny air pockets within its cellular structure. Since thermal conductivity increases with relative density, wood is a better insulator than dense construction materials. With respect to thermal performance, wood-frame building enclosures are inherently more efficient than other common construction materials, largely because of reduced thermal bridging through the wood structural elements, including the wood studs, columns, beams, and floors. Wood loses less heat through conduction than other building materials and wood-frame construction techniques support a wide range of insulation options, including stud cavity insulation and exterior rigid insulation. Research and monitoring of buildings is increasingly demonstrating the importance of reducing thermal bridging in new construction and reducing thermal bridges in existing buildings. The impact of thermal bridges can be a significant contributor to whole building energy use, the risk of condensation on cold surfaces, and occupant comfort. Focusing on the building envelope and ventilation at the time of construction makes sense, as it is difficult to make changes to these systems in the future. High performance buildings typically cost more to build than conventional construction, but the higher purchase price is offset, at least in part, by lower energy consumption costs over the life cycle. What’s more, high performance buildings are often of higher quality and more comfortable to live and work in. Making buildings more energy efficient has also been shown to be one of the lowest cost opportunities to contribute to energy reduction and climate change mitigation goals. Several certification and labeling programs are available to builders and consumers address reductions in energy consumption within buildings. Natural Resources Canada (NRCan) administers the R-2000 program, which aims to reduce home energy requirements by 50 percent compared to a code-built home. Another program administered by NRCan, ENERGY STAR®, aims to be 20 to 25 percent more energy efficient than code. The EnerGuide Rating System estimates the energy performance of a house and can be used for both existing homes and in the planning phase for new construction. Other certification programs and labelling systems have fixed performance targets. Passive House is a rigorous standard for energy efficiency in buildings to reduce the energy use and enhance overall performance. The space heating load must be less than 15 kWh/m2 and the airtightness must be less than 0.6 air changes per hour at 50 Pa, resulting in ultra-low energy buildings that require up to 90 percent less heating and cooling energy than conventional buildings. The NetZero Energy Building Certification, a program operated by the International Living Future Institute, is a performance-based program and requires that the building have net-zero energy consumption for twelve consecutive months. Green Globes and Leadership in Energy and Environmental Design (LEED) are additional building rating systems that are prevalent in the building design and construction marketplace. For further information, refer to the following resources: Thermal Performance of Light-Frame Assemblies – IBS No.5 (Canadian Wood Council) National Energy Code of Canada for Buildings Natural Resources Canada BC Housing Passive House Canada Green Globes Canadian Green Building Council
Changement climatique
Les préoccupations liées au changement climatique encouragent la décarbonisation du secteur du bâtiment, y compris l'utilisation de matériaux de construction responsables de moins d'émissions de gaz à effet de serre (GES) et l'amélioration des performances opérationnelles tout au long du cycle de vie des bâtiments. Responsable de plus de 10 % des émissions totales de GES au Canada, le secteur du bâtiment joue un rôle important dans l'atténuation du changement climatique et l'adaptation à celui-ci. La réduction de l'impact des bâtiments sur le changement climatique offre un rendement environnemental élevé pour un investissement économique relativement faible. Le gouvernement du Canada, en tant que signataire de l'Accord de Paris, s'est engagé à réduire les émissions de GES du Canada de 30 % par rapport aux niveaux de 2005 d'ici 2030. En outre, le Cadre pancanadien sur la croissance propre et le changement climatique reconnaît que les produits forestiers et ligneux peuvent contribuer à la stratégie nationale de réduction des émissions en renforçant le stockage du carbone dans les forêts, en augmentant l'utilisation du bois dans la construction, en produisant du carburant à partir de la bioénergie et des bioproduits et en favorisant l'innovation dans le développement de produits biologiques et les pratiques de gestion forestière. Le Groupe d'experts intergouvernemental sur l'évolution du climat (GIEC) se fait également l'écho de l'importance du secteur de la sylviculture et des produits du bois en tant que composante essentielle de l'atténuation des effets du changement climatique, en affirmant qu'une stratégie de gestion durable des forêts visant à maintenir ou à augmenter les stocks de carbone forestier tout en produisant du bois, des fibres ou de l'énergie, génère le plus grand bénéfice durable pour atténuer le changement climatique. En outre, le GIEC déclare que "les options d'atténuation du secteur forestier comprennent l'extension de la rétention de carbone dans les produits ligneux récoltés, la substitution de produits et la production de biomasse pour la bioénergie". L'industrie forestière canadienne s'engage à éliminer 30 mégatonnes de dioxyde de carbone (CO2) par an d'ici 2030, ce qui équivaut à 13 % des engagements nationaux du Canada dans le cadre de l'Accord de Paris. Plusieurs mécanismes seront utilisés pour relever ce défi, notamment : le déplacement de produits, en utilisant des produits biosourcés à la place de produits et de sources d'énergie dérivés de combustibles fossiles ; les pratiques de gestion forestière, y compris l'utilisation accrue, l'amélioration de l'utilisation des résidus et de la planification de l'utilisation des terres, et l'amélioration de la croissance et des rendements ; la prise en compte des réservoirs de carbone des produits biosourcés à longue durée de vie ; et une plus grande efficacité dans les processus de fabrication des produits du bois Le Canada abrite 9 pour cent des forêts du monde, qui ont la capacité d'agir comme d'énormes puits de carbone en absorbant et en stockant le carbone. Chaque année, le Canada exploite moins d'un demi pour cent de ses terres forestières, ce qui a permis à la couverture forestière du pays de rester constante au cours du siècle dernier. La gestion durable des forêts et les exigences légales en matière de reboisement permettent de maintenir ce vaste réservoir de carbone. Une forêt est un système naturel considéré comme neutre en carbone tant qu'elle est gérée de manière durable, ce qui signifie qu'elle doit être reboisée après la récolte et ne pas être convertie à d'autres utilisations. Le Canada possède certaines des réglementations les plus strictes au monde en matière de gestion forestière, exigeant une régénération réussie après l'exploitation des forêts publiques. Lorsqu'elles sont gérées de manière responsable, les forêts constituent une ressource renouvelable qui sera disponible pour les générations futures. Le Canada est également un leader mondial en matière de certification forestière volontaire par une tierce partie, ce qui renforce l'assurance d'une gestion durable des forêts. Les programmes de gestion durable des forêts et les systèmes de certification s'efforcent de préserver la quantité et la qualité des forêts pour les générations futures, de respecter la diversité biologique des forêts et l'écologie des espèces qui y vivent, ainsi que les communautés concernées par les forêts. Les entreprises canadiennes ont obtenu la certification d'une tierce partie sur plus de 150 millions d'hectares de forêts, ce qui représente la plus grande superficie de forêts certifiées au monde. La forêt représente un réservoir de carbone, stockant le carbone biogénique dans les sols et les arbres. Le carbone reste stocké jusqu'à ce que les arbres meurent et se décomposent ou brûlent. Lorsqu'un arbre est coupé, 40 à 60 % du carbone biogénique reste dans la forêt ; le reste est retiré sous forme de grumes et une grande partie est transférée dans le réservoir de carbone des produits du bois dans l'environnement bâti. Les produits du bois continuent à stocker ce carbone biogénique, souvent pendant des décennies dans le cas des bâtiments en bois, retardant ou empêchant la libération d'émissions de CO2. Les produits du bois et les systèmes de construction ont la capacité de stocker de grandes quantités de carbone ; 1 m3 de bois d'œuvre S-P-F stocke environ 1 tonne d'équivalent CO2. La quantité de carbone stockée dans un produit en bois est directement proportionnelle à la densité du bois. Au Canada, une maison unifamiliale moyenne stocke près de 30 tonnes d'équivalent CO2 dans les produits du bois utilisés pour sa construction. La plupart des produits de construction biosourcés stockent en fait plus de carbone dans la fibre de bois qu'ils n'en libèrent au cours des phases de récolte, de fabrication et de transport de leur cycle de vie. En général, les produits biosourcés, comme le bois qui pousse naturellement avec l'aide du soleil, ont des émissions intrinsèques plus faibles. Les émissions intrinsèques résultent des processus de production des matériaux de construction, depuis l'extraction ou la récolte des ressources jusqu'à la fin de vie, en passant par la fabrication, le transport et la construction. La bioénergie produite à partir de résidus biosourcés, tels que l'écorce d'arbre et la sciure de bois, est principalement utilisée pour générer de l'énergie pour la fabrication de produits en bois en Amérique du Nord. Les produits de construction en bois ont de faibles émissions de GES intrinsèques parce qu'ils sont cultivés à l'aide d'énergie solaire renouvelable, qu'ils utilisent peu d'énergie fossile pendant la fabrication et qu'ils ont de nombreuses options de fin de vie (réutilisation, recyclage, récupération d'énergie). Les produits du bois peuvent se substituer à d'autres matériaux de construction et sources d'énergie à plus forte intensité de carbone. Les émissions de gaz à effet de serre sont ainsi évitées en utilisant des produits du bois à la place d'autres produits de construction à plus forte intensité de gaz à effet de serre. Des facteurs de déplacement (kg de CO2 évité par kg de bois utilisé) ont été estimés pour calculer la quantité de carbone évitée grâce à l'utilisation de produits du bois dans la construction de bâtiments. Pour de plus amples informations, veuillez consulter les ressources suivantes : Addressing Climate Change in the Building Sector - Carbon Emissions Reductions (Conseil canadien du bois) Resilient and Adaptive Design Using Wood (Conseil canadien du bois) CWC Carbon Calculator Canada's Forest Products Industry "30 by 30" Climate Change Challenge (Association des produits forestiers du Canada) www.naturallywood.com www.thinkwood.com Building with wood = Proactive climate protection (Binational Softwood Lumber Council and State University of New York) Natural Resources Canada Pan-Canadian Framework on Clean Growth and Climate Change (Gouvernement du Canada) Intergovernmental Panel on Climate Change (Groupe d'experts intergouvernemental sur l'évolution du climat)
Fondations permanentes en bois
A permanent wood foundation (PWF) is an engineered construction system that uses load-bearing exterior light-frame wood walls in a below-grade application. A PWF consists of a stud wall and footing substructure, constructed of approved preservative-treated plywood and lumber, which supports an above-grade superstructure. Besides providing vertical and lateral structural support, the PWF system provides resistance to heat and moisture flow. The first PWF examples were built as early as 1950 and many are still being used today. A PWF is a strong, durable and proven engineered system that has a number of unique advantages: energy savings resulting from high insulation levels, achievable through the application of stud cavity insulation and exterior rigid insulation (up to 20% of heat transfer can occur through the foundation); dry, comfortable living space provided by a superior drainage system (which does not require weeping tile); increased living space since drywall can be attached directly to foundation wall studs; resistance to cracking from freeze/thaw cycles; adaptable to most building designs, including crawl spaces, additions and walk-out basements; one trade required for more efficient construction scheduling; buildable during winter with minimal protection around footings to protect them from freezing; rapid construction, whether framed on site or pre-fabricated off-site; materials are readily available and can be efficiently shipped to rural or remote building sites; and long life, based on field and engineering experience. PWFs are suitable for all types of light-frame construction covered under Part 9 ‘Housing and Small Buildings’ of the National Building Code of Canada (NBC), that is, PWF can be used for buildings up to three-storeys in height above the foundation and having a building area not exceeding 600 m2. PWFs can be used as foundation systems for single-family detached houses, townhouses, low-rise apartments, and institutional and commercial buildings. PWFs can also be designed for projects such as crawlspaces, room additions and knee-wall foundations for garages and manufactured homes. There are three different types of PWFs: concrete slab or wood sleeper floor basement, suspended wood floor basement and an unexcavated or partially excavated crawl space. Lumber studs used in PWF are typically 38 x 140 mm (2 x 6 in) or 38 x 184 mm (2 x 8 in), No. 2 grade or better. Improved moisture control methods around and beneath the PWF result in comfortable and dry below-grade living space. The PWF is placed on a granular drainage layer which extends 300 mm (12 in) beyond the footings. An exterior moisture barrier, applied to the outside of the walls, provides protection against moisture ingress. Caulked joints between all exterior plywood wall panels and at the bottom of exterior walls is intended to control air leakage through the PWF, but also eliminates water penetration pathways. The result is a dry basement that can be easily insulated and finished for maximum comfort and energy conservation. All lumber and plywood used in a PWF, except for specific components or conditions, must be treated using a water-borne wood preservative and identified as such by a certification mark stating conformance with CSA O322. Corrosion-resistant nails, framing anchors and straps that are used to fasten PWF-treated material must be hot-dipped galvanized or stainless steel. Exterior moisture and vapour barriers must be at least 0.15 mm (6 mil) in thickness. Dimpled drainage board is often specified as an exterior moisture barrier. For further information, refer to the following references: Permanent Wood Foundations (Canadian Wood Council) Permanent Wood Foundations 2023 – Durable, Comfortable, Adaptable, Energy efficient, Economical (Wood Preservation Canada and Canadian Wood Council) Wood Design Manual (Canadian Wood Council) Wood Preservation Canada CSA S406 Specification of permanent wood foundations for housing and small buildings CSA O322 Procedure for certification of pressure-treated wood materials for use in permanent wood foundations CSA O86 Engineering design in wood National Building Code of Canada
Durabilité par conception
La "durabilité par la conception" est l'aspect le plus important des solutions durables. Il s'agit d'abord d'utiliser du bois sec, de le stocker de manière appropriée pour s'assurer qu'il reste sec, puis de concevoir le bâtiment de manière à protéger le bois ou, si le bois est exposé, de le concevoir de manière à ce qu'il n'accumule pas d'humidité. Il faut également veiller à ce que l'enveloppe du bâtiment soit conçue de manière à évacuer l'eau en vrac, à empêcher l'eau et la vapeur de pénétrer dans l'enveloppe et à évacuer l'eau qui s'y infiltre.
