Canadian Building Research Articles

Comparing Canadian and Norwegian moisture indices for building climate adaptation

To evaluate the suitability of materials and solutions in building envelopes, it is necessary to quantify the relevant climate loads. The critical climate load is typically a combination of multiple parameters, such as temperature and precipitation. Climate indices may be used for finding critical climate loads, and their use helps guide design choices when adapting to local climates. The purpose of this study is to evaluate the suitability of the Canadian Moisture Index (MI) for use in Norway. The values of MI are linked to design recommendations in the Canadian building code, thus enabling a tangible link between index values and moisture design practice. MI has been calculated for 12 locations in Norway, and compared to two indices already in national use: the driving rain index (DRI) and wood decay potential index (WDPI). The applicability of a climate index as a design tool depends on (1) describing a relevant climate stress; (2) logical differentiation of values, and; (3) translating index values to design recommendations. These are fulfilled for MI in a Canadian context, thus making it applicable as a design tool. However, significant adaptation may be required for the index to be adopted to a Norwegian context. As MI and DRI have a similar field of application, introducing MI into a Norwegian context may therefore be redundant. A drawback with the Norwegian indices is the relative weak link between index values and design recommendations, thus further development of recommendations based on index values may improve their applicability as design tools.

Performance-based wind and earthquake design framework for tall steel buildings with ductile detailing

According to the Canadian building code, wind design relies on prescriptive static methods, which lead to a conservative design. In consequence, in moderate seismic regions where both winds and earthquakes are critical, the size of ductile members resulting from seismic design, and especially those of bottom floors, may not accommodate the elastic wind demand and larger member sizes are required. In general, this is the case of rectangular buildings, where in the direction perpendicular to the largest building dimension, the base shear due to elastic wind demand is critical, while in the orthogonal direction the seismic demand governs. Hence, in one direction, the allowable base shear increases above the seismic demand, which results in reduced energy dissipation and amplification of torsion. To mitigate the incoherence in the current building code, a refined code-based multi-hazard design approach, targeting performance of tall steel buildings in Eastern Canada, is proposed. Thus, accounting for the building’s overstrength and allowing limited controlled inelasticity under high-intensity wind, a wind-related reduction factor RW is proposed to reduce the design wind load. The method is implemented for the design of two identical 15-storey steel braced frame buildings, but of different occupancy, hospital and office, respectively. Nonlinear response history analyses are performed to verify the member sections of steel braced frames, while the parameters investigated are the interstorey drift, residual interstorey drift and floor acceleration. Then, seismic and wind incremental dynamic analyses provide insight into the multi-hazard dynamic response of buildings subjected to ground motions and winds of increasing intensity. The fragility concept is used to quantify the performance of studied buildings designed with RW = 2 versus the building designed with RW = 1. Comfort criteria, as well as, the drift acceptance criteria, commonly considered in research and practice, are used to verify the effectiveness of the proposed method. The nonlinear response of the studied buildings at the design level and beyond shows that using RW = 2 for wind design does not change the response at design level, but slightly decreases the collapse capacity within the acceptable range.

Open-Source Vertical Swinging Wood-Based Solar Photovoltaic Racking Systems

Vertical bifacial solar photovoltaic (PV) racking systems offer the opportunity for large-scale agrivoltaics to be employed at farms producing field crops with conventional farming equipment. Unfortunately, commercial proprietary vertical racks cost more than all types of conventional PV farm racking solutions. To overcome these cost barriers, this study reports on the development of a new wood-based PV racking design. The open-source design consists of a hinge mechanism, which reduces mechanical loading and enables wood to be used as the main structural material, and is the first of its kind. This open-source vertical wood-based PV rack is (i) constructed from locally accessible (domestic) renewable and sustainable materials, (ii) able to be made with hand tools by the average farmer on site, (iii) possesses a 25-year lifetime to match PV warranties, and (iv) is structurally sound, following Canadian building codes to weather high wind speeds and heavy snow loads. The results showed that the capital cost of the racking system is less expensive than the commercial equivalent and all of the previous wood-based rack designs, at a single unit retail cost of CAD 0.21. The racking LCOE is 77% of the cost of an equivalent commercial racking system using retail small-scale component costs, and is 22%, 34%, and 38% less expensive than commercial metal vertical racking, wood fixed tilt racking, and wood seasonal tilt racking costs, respectively. Overall, wooden vertical swinging PV racking provides users with a low-cost, highly available alternative to conventional metal vertical racking, along with a potential increase in energy yield in high wind areas thanks to its unique swinging mechanism.

Assessing and mitigating overheating risk in existing Canadian school buildings under extreme current and future climates

Canadian buildings have been primarily designed to withstand cold and long winters, not hot summers. With climate change and the increase in the intensity and severity of heatwaves, it has become important to investigate overheating in buildings. However, there are limited studies on assessing and mitigating the overheating risk in existing buildings that house vulnerable populations in cold climates, especially in Canada. This paper provides a framework for the systematic assessment of overheating risks and the development of passive mitigation strategies to reduce the overheating risks without increasing cooling energy consumption under current and future climates with simulation models that are calibrated based on measured indoor air temperatures and outdoor weather conditions. The framework is applied to a school building built in 1958. The calibrated building model achieved an RMSE of less than 0.6 °C compared with measurements, a Maximum-Absolute-Difference of less than 1.9 °C, and a 1 °C Percentage-Error of less than 10 %. The simulation results from the calibrated model predicted 110 overheating hours during the year 2020. The use of exterior blind roll or a combination of night cooling and other mitigation measures that reduce solar heat gain can achieve acceptable thermal conditions. In 2044 (the future extreme midterm year), night cooling with the exterior blind roll shading would be required during extreme heat events. Whereas during 2090 (the future long-term extreme year), additional mitigation measures such as a cool roof may be required to achieve an acceptable level of thermal conditions in the school.

An update on the seismic categorization for seismic risk assessment of existing Canadian buildings

An investigation has been done to update key input parameters in the recent seismic-risk-screening tools developed by the National Research Council Canada for the six seismic categories. In this study, the seismic categorization system in the recent seismic-risk-screening tools of the National Research Council Canada is extended to include Canadian buildings abroad by including threshold peak ground acceleration values, a more global set of modified Mercalli intensity, peak ground acceleration, and spectral response acceleration and peak ground acceleration relationships. The relationships among spectral response acceleration, peak ground acceleration, and peak ground velocity values have been derived using least-squares regression analyses to obtain the threshold values of both peak values associated with various modified Mercalli intensity values for each seismic category. Based on the updated relationships, the seismic categorization system is applied to 679 locations in Canada and 226 locations outside Canada.

Temporally-differentiated biogenic carbon accounting of wood building product life cycles

Although standards have identified temporary carbon storage as an important element to consider in wood product LCAs, there has been no consensus on a methodology for its accounting. This work aims to improve the accounting of carbon storage and fluxes in long-life wood products in LCA. Biogenic carbon from harvested roundwood logs were tracked using the Carbon Budget Model Framework for Harvested Wood Products (CBMF-HWP). Carbon flows through wood product manufacturing, building life and end-of-life phases, and carbon stocks and fluxes from harvest to the atmosphere were estimated. To cover the products commonly used in the Canadian building industry, a range of softwood products types, provinces and territories and building lifetimes were considered. In addition, policy scenarios were considered in order to model the effects of dynamic parameters through time as a policy target is reached. Most wood products have similar emissions profiles, though cross-laminated timber has higher sawmill emissions and oriented-strand board has higher initial post-demolition emissions. The region of construction is also predictive of the initial post-demolition emissions. Higher recycling rates shift materials from landfills into subsequent product systems, thus avoiding landfill emissions. Landfill decay rates are affected by climate and results in a large range of landfill emissions. The degree of postponement of end-of-life emissions is highly dependent upon the wood product type, region and building lifespan parameters. This work develops biogenic carbon profiles that allows for modelling dynamic cradle-to-grave LCAs of Canadian wood products.

Engineered wood products as substitutes in the Canadian building construction industry

Engineered wood products as substitutes in the Canadian building construction industry

Where drills differ from evacuations: A case study on Canadian buildings

Planned egress drills are required by building codes around the world, and are commonly used to both train occupants and assess evacuation procedures. However, capturing the idea of a “successful” drill is often difficult. Data from both drills and unplanned evacuations are often incomplete and unreliable, which raises a key question: How well-matched are planned egress drills and unplanned evacuations in terms of their properties and outcomes? That is, are drills a good model of evacuation? In this paper, we compare 93 planned egress drills and 23 unplanned evacuations, which occurred in Canadian office buildings over a span of four years. Our two main findings are that (1) planned egress drills differ from unplanned evacuations in terms of frequency, timing, and outcome (e.g., reported total evacuation time), and (2) the reported number of occupants correlates with total evacuation time. These findings motivate a discussion of the strengths and weaknesses of the current approach to data reporting, and we highlight potential implications for (and limitations of) the current drill model.

Engineered wood products as substitutes in the Canadian building construction industry

Engineered and reconstituted wood products play an important role in building construction, and have positive environmental impacts. However, the wood products compete with other construction material (concrete and steel) in terms of prices in the Canadian building construction industry, and the price competition has not been explored in past literature. In order to promote the use of wood and wood-based products, there is a need to understand how prices influence the choice of construction material. We estimated the own and cross-price elasticities of demand of construction material in Canada using standard log-linear regression models with consumption and price data from 1990 to 2017. Our study shows that engineered and reconstituted wood products are substitutes for cement and steel, and hence there is a need to focus on the development of these value-added forest products, to create sustainable local economies that are economically viable, environmentally sound and socially responsible.

Dynamic greenhouse gas life cycle inventory and impact profiles of wood used in Canadian buildings

Wood is increasingly promoted due to its reported low climate change impacts; however, the literature reports provides high variability of climate change impact scores, making comparisons with non-wood materials difficult. The objective of this study is to calculate a database of life cycle inventories (LCI) and dynamic climate change impacts (DCCI) of wood building products, for different use contexts across Canada. Temporally differentiated gate-to-gate LCIs were developed, to which dynamic life cycle assessment (DLCA) was applied, yielding a modular database of cradle-to-grave LCIs and DCCIs of wood products. Four wood product case studies were chosen to demonstrate the use of the modular LCI and DCCI database of wood product use in buildings. The results show that most wood building products provide overall net negative climate change impact scores, though for some wood product specifications results show net positive climate change impacts. Results are sensitive to a few factors, including ecosystem carbon cost (ECC), wood carbon content, building lifespan and end-of-life. This research develops a gate-to-gate LCI and DCCI database for each life cycle stage of wood building products, allowing life cycle assessment (LCA) practitioners to calculate DCCI results with respect to a chosen time horizon relevant for decision-making. This modular database would be particularly useful to those practitioners wishing to account for biogenic carbon in wood product life cycle assessment, which is currently quite difficult due to a lack of data. It could also be readily implemented into LCA tools to support building designers in sustainable building material selection.

Overheating risk of a single-family detached house built at different ages under current and future climate in Canada

With the anticipated increase in temperature and solar radiation and frequency of extreme weather conditions due to climate change, buildings typically designed/built in Canadian cold climates would experience increased risks of summer overheating. This paper focuses on how these existing buildings perform under a current extreme year and projected future climates. Results show that the thermal conditions of a single-family detached house built in 1964 and 1990 are more comfortable than the house built to meet the current National Energy Code of Canada for Buildings (NECB) and high energy-efficient building (HEEB) without including natural ventilation by up to 50%. On the other hand, when natural ventilation is included, the house built to NECB and HEED are more comfortable. Sensitivity analysis is carried out to evaluate the influence of five design parameters, i.e. wall and roof insulation, airtightness, U-value and SHGC of windows. Sensitivity analysis shows that wall insulation, airtightness, and windows U-value are the three most significant parameters influencing the overheating risk without natural ventilation. With natural ventilation, the SHGC of windows is the most influencing parameter in reducing overheating risk. This paper confirms that the Canadian buildings have the overheating risk over the hot summer experienced over the past a few years and the risk will be increased in the future. Natural ventilation as a mitigation measure, which has been relied on by building designers in Canada will not be sufficient to remove excess heat or provide thermal comfort to residents. Other mitigation strategies such as shading to reduce the heat gain during the summer, are needed.

Real-Time Emulation of Residential Buildings by Hardware Solution of Multi-Layer Model

Building modeling and consumption analysis are important elements of smart grid applications. The models of residential buildings in Nordic countries, where multi-layer slabs are mandatory to meet energy efficiency requirements, the modeling task becomes particularly challenging. In fact, the complexity of the detailed model rises as the number of layers and thermal zones increases. In some cases, this situation limits the implementation of model-based predictive control where the computation time for execution of the model must be as short as possible to achieve optimized loop time performance. To that end, this paper proposes the development of a modular, accurate and flexible real-time multi-zone and multi-layer building emulation system representing the dynamic thermal-electric behavior of residential buildings. The proposed hardware implementation architecture includes space and water heating systems, which are the main consuming loads in Nordic countries. The emulation system can perform in accelerated simulation or in real-time modes, either for one building or for a virtual park of buildings. Experimental validation using measurement data of occupied Canadian buildings with different insulation characteristics and using a hardware-in-the-loop configuration has permitted to corroborate the usefulness of the proposed emulation system.

Canadian Mass Timber Demonstration Projects Initiatives

In order to expedite market acceptance and facilitate the commercial uptake of wood products and systems in Canada, it is necessary to showcase such applications through high-rise and non-residential building demonstration projects. This paper presents recent initiatives by the Government of Canada focused on increasing use of wood as a green building material in infrastructure projects by supporting such demonstration projects. The objective of Green Construction through Wood (GCWood) program (launched in 2017) is to support the design and construction of several high-rise and non-residential timber demonstration buildings and bridges in Canada through expression of interest (EOI) calls. The program is also supporting research and development activities to facilitate acceptance of provisions that would allow for the construction of tall wood buildings in Canadian building codes and advanced wood education at engineering and architectural colleges and universities to help develop the future design capacity in Canada.

Energy hubs optimization for smart energy network system to minimize economic and environmental impact at Canadian community

Recently, significant attention has been given to distributed power and thermal generation instead of centralized power plants. This study investigates the energy production of five energy hubs in a smart energy network set up for minimizing the energy cost and Greenhouse Gas (GHG) emissions under different technology scenarios at a Canadian community. The energy hubs present twenty Canadian buildings’ archetypes: sixteen single residential buildings, primary school, quick service restaurant, office, and supermarket. The hubs are interconnected by thermal and electricity grid and are sharing the locally generated energy to meet the demand loads. Three scenarios, each employing different energy technologies at hubs level were developed and investigated. The performance results were compared to a reference case.A complex optimization model was developed to minimize the energy consumption and environmental impact. The results showed that integrating different residential and commercial buildings with associated generation technologies in smart energy network allows energy sharing among them, enhancing overall efficiency and reducing energy and emissions costs. The study also showed that with this approach an electrical storage capacity of 25% of average electrical load had the lowest energy cost and environmental impact. In addition, it was found that integration of photovoltaic and electrical energy storage technologies would provide GHG savings up to 43% when compared to reference technologies.

Politicking for Postwar Modernism: The Architectural Research Group of Ottawa and Montreal

The diffusion of modernist principles in Canadian building and planning occurred through many channels, but among these the Architectural Research Group of Ottawa and Montreal played a crucial role. Formed in 1938 to conduct research into postwar reconstruction, the group produced articles, radio addresses, and exhibitions in an effort to nurture modernist sentiment across the country. For these young architects, the federal government’s commitment to replanning and rebuilding postwar Canadian cities presented them with an opportunity to intervene in the future of Canadian practice. They decried the “backwardness” of conservative practitioners while promoting the ideas of a European avant-garde and orchestrating numerous transatlantic exchanges. This article discusses the group’s role in politicking for architectural and urban modernism, as well as the contributions of some of its key members. It shows that Canadian professionals were not simply passive receptors of international modernism but played an active part in shaping these ideas during the immediate postwar period, and that Canada’s federal government played a unique role in accelerating this process by allowing modernist architects and planners to operate within and through a number of government-sponsored agencies.

Re-examination of steel frame office buildings in preventing collapse when subject to intense fires

The purpose of the paper is to investigate the extent to which present-day design of steel framed buildings is susceptible to total collapse when subjected to extreme fire events. We select a 50 storey structure in which 2 and 4 adjacent storeys located at different above-ground heights are, in separate scenarios engulfed in raging fires. A total of 8 scenarios are analyzed, employing Newtonian mechanics and realistic energy dissipating properties of H-shaped columns and normal concrete floor slabs possessing secondary (shrinkage and temperature) reinforcement alone. While the present Canadian building code is the basis for our column designs, other standards provide very similar specifications. Although fire proofing is required in virtually all high rise building construction, we are excluding such materials in order to simplify the analyses, but clearly do not advocate its omission – quite the opposite in fact. As well, attributes such as floor beams, partitions and furnishings of every description, all of which would in practice participate in absorbing the kinetic energy of a crush-down upper block are excluded. Despite such a vast array of conservative assumptions, it is shown that partial collapse may occur during crush-down, however, in no case will total collapse be the consequence. These results should provide some comfort to code writers that their requirements should indeed prevent the most catastrophic of failures due to fires.

FIRE SAFETY OF CLT BUILDINGS IN CANADA

This article provides an overview of the code requirements pertinent to large cross-laminated timber (CLT) buildings and the methods for meeting the requirements in Canada. Canadian building codes are objective-based. Compliance with the code is achieved by directly applying the acceptable solutions up to certain prescriptive building sizes (height and area) or by developing alternative solutions beyond the height and area limits. The fire safety design for a CLT building larger than the prescriptive limit must demonstrate that the building will achieve at least the minimum level of performance afforded by noncombustible construction in limiting the structural involvement in fire and contribution to the growth and spread of fire during the time required for occupant evacuation and emergency responses.

Seismic Base Shear Modification Factors for Timber-Steel Hybrid Structure: Collapse Risk Assessment Approach

AbstractIn this paper, to supplement the Canadian building code for a timber-steel hybrid structure, over-strength, and ductility-related force modification factors are developed and validated usin...

There’s No Place like Home: Designing for Long-Term Residential Care in Canada

This article explores the architecture of long-term residential care (LTRC) design in Canada. Because choosing residential care over aging in place is widely perceived as a personal, social, and familial failure, LTRC is fraught with ageist connotations. Relatedly, chronic underfunding and low prestige make many LTRC buildings nearly invisible. Like hotels, university residences, and even summer camps, LTRC buildings try to look residential, but their functional programs are wholly institutional. We examine how these contradictions are legible in Canadian LTRC architecture, drawing on a fictional example—Joan Barfoot’s Exit Lines—that demonstrates how the real LTRC buildings we discuss are popularly understood. We also draw on an extensive set of ethnographic notes from a team-based research project for which members visited sites across Canada, with a promise of anonymity. We argue here that LTRC buildings fade into our neighbourhoods and cities (and even budgets), because their gestures to institutional and to suburban architectural vernacular traditions are unremarkable, but that they require attention precisely because of this uneasy ambivalence. We highlight a handful of Canadian buildings whose architects have broken the mould of LTRC design and offered fresh alternatives to argue that home might not be the only or even the best model for designing LTRC.

Politicking for Postwar Modernism: The Architectural Research Group of Ottawa and Montreal

The diffusion of modernist principles in Canadian building and planning occurred through many channels, but among these the Architectural Research Group of Ottawa and Montreal played a crucial role. Formed in 1938 to conduct research into postwar reconstruction, the group produced articles, radio addresses, and exhibitions in an effort to nurture modernist sentiment across the country. For these young architects, the federal government’s commitment to replanning and rebuilding postwar Canadian cities presented them with an opportunity to intervene in the future of Canadian practice. They decried the “backwardness” of conservative practitioners while promoting the ideas of a European avant-garde and orchestrating numerous transatlantic exchanges. This article discusses the group’s role in politicking for architectural and urban modernism, as well as the contributions of some of its key members. It shows that Canadian professionals were not simply passive receptors of international modernism but played an active part in shaping these ideas during the immediate postwar period, and that Canada’s federal government played a unique role in accelerating this process by allowing modernist architects and planners to operate within and through a number of government-sponsored agencies.