Building Better with Steel

Guidelines for lowering GHG emissions in conventional steel structures

By Scott Norris

Finding ways to reduce the carbon footprint of buildings is on every professional’s mind. While certification programs like LEED, Toronto Green Building Standards, and CAGBC Net Zero Carbon Building Standard have helped guide the industry in terms of reducing the environmental impact of buildings, including Global Warming Potential (GWP), it is an ever evolving mission.

The steel industry has begun to take a life cycle approach, reducing the emissions associated with the production of the material, the construction process, as well as the energy efficiency over its lifespan. Regardless of the building type, occupancy, or design material, it is critical that consultants reaffirm their design approaches to ensure they align with this more holistic goal.

In buildings where, large clear spans are required by the program, a steel structure with conventional cast in place concrete foundations is often preferred for reasons of economy. Steelwork that is efficiently fabricated off-site offers quality-assured, fully tested, and traceable products. On-site construction is fast and has minimal adverse local environmental impacts. These characteristics lend themselves well to warehouses, community centres, transit buildings, data centres and low-rise offices, among others.

For those involved with these building types for which steel is better suited, the overall embodied carbon in the structure can be reduced in several ways:

1. Design efficiently and purposefully. For example:

a. The consultants must work together to determine accurate design loading; excess loading compounds exponentially in the member design phase.

b. Work with the consultants and contractors to understand serviceability requirements of floors, finishes and curtain walls.

c. During preliminary building layout, opt for bays with a 3:4 rectangular aspect ratio for girders to beams. Also, aim for bay sizes of 7.5m x 10m to 10m x 13m to maximize deck spans and optimize framing weight and depth.

d. Utilize efficient framing systems, such as: SIN Beams, composite beams, gerber girder framing, open web steel joists (OWSJs), trusses, arches and tension only members wherever possible.

e. Avoid inefficient systems such as moment frames, transfers of gravity structure, Vierendeel trusses, etc., wherever possible.

f. Understand the transportation impacts created by the materials that you are choosing. Truck transportation produces 17 kg CO2 / tonne / 100 km, while train is 33% of that and marine shipping is 5%.

g. Prioritize members that are produced using an electric arc furnace (EAF). North American manufacturers typically use EAFs to manufacture steel for hot rolled shapes like wide-flange members, angles and channels.

h. Understand the benefits and limitations of hollow structural sections (HSS). These members are more efficient from a material standpoint, however if they are purchased in Canada, they currently come from basic oxygen furnace (BOF) coil which increases embodied carbon and reduces recycled content. If the HSS is purchased from US mills it is more likely that the coil will be coming from EAF.

This will change in coming years when the EAF mills at Algoma Steel and Dofasco come online in 2026.

i. Understand that plate, and cold form steel is often produced in using BOF. This impacts items such as roof deck for example which has high GWP values.

j. Investigate the use of high yield strength for tension members, simply supported columns, beam columns, and simply supported laterally restrained beams

k. Do not forget about the concrete works. Design foundations, slab on grade, floor deck and other elements efficiently and utilize reinforcement only as required Alternately, use fibre reinforcement instead of steel.

l. Work with the concrete suppliers to utilize low carbon mixes.

Scott Norris is Director of Engineering Solutions at Steelcon.

Find out more about carbon neutral steel designs at www.steelcongoc.com, follow Scott Norris on LinkedIn or contact him directly, snorris@steelcongoc.com.

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November 12, 2024November 14, 2024

Fast + Epp head office

Urban infill building highlights hybrid construction

Completed in 2022, the Fast + Epp Home Office is an elegant, economic and highly transferable example of an urban densification project whose approach to material use is a pragmatic hybrid of mass timber, steel and concrete.

The four-storey mixed use building is located close to the city centre on the south shore of False Creek, an eclectic light industrial area that has undergone dramatic transformation over the past decade.

The 137.1m x 13.3m site is zoned for an FSR of 3.0, of which 1.0 must be an industrial use located at street level. A 1.2m right-of-way reduced the width of the site, forcing a portion of the industrial use to the second level and making vertical fire separations necessary.

Below grade, the reduced width required the elimination of interior columns in favour of a clear span, post-tensioned slab to accommodate a single row of parking and an aisle. This in turn influenced the design of the above ground structure, where clear spanning glulam beams informed both the subdivision of space and the routing of exposed building services.

These constraints required a pragmatic design response, both in the use of space and choice of materials. This approach resonated with Fast + Epp (both client and structural engineer for the project) and with f2a architecture, which aims “to create buildings that are minimal, energy efficient, have healthy interiors and a direct relationship to their site.”

To maximize leasable area within the zoning envelope, floor to floor heights were carefully manipulated according to use; Level 1 being 4.8m; Levels 2 and 3 being 3.6m and the Level 4 penthouse 2.6m. There is an interconnected floor space (IFS) between Levels 3 and 4. There is a 2-hour fire separation between industrial and office occupancies, with 1-hour required for the other floors and supporting structure.

The IFS forms an atrium, serving as a meeting area and social space for the Fast + Epp office. The lower level has a small kitchen, while the upper level accommodates ‘touch down’ work stations and (being smaller than the lower floors) has access to a roof terrace.

Project Credits

Owner/Developer Fast + Epp Structural Engineers
Architect f2a architecture
General Contractor Companion Construction Ltd
Building Code GHL Consultants
Structural Engineer Fast + Epp Structural Engineers
Interior Design HCMA Architecture + Design
Mechanical Engineering Impact Engineering
Photos Michael Elkan
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November 12, 2024November 12, 2024

Navigating the transformation

The evolving role of wood in sustainable construction

By Peter Moonen

Around the globe, the construction sector is in the midst of a profound transformation. Faced with an array of social, economic, and environmental challenges, the industry is adapting to new demands and regulations. As urban populations swell—80% of the world’s population is projected to live in cities by 2050, with Canada already at 81%—the need for affordable, high-performance multifamily housing has never been more pressing. The sector is grappling with rising operational costs, material expenses, and a shrinking labour force, all while striving to enhance energy efficiency and affordability in rapidly densifying urban areas.

The Carbon Conundrum

Decarbonizing construction is a crucial part of this transformation. For decades, regulations have focused on operational energy, pushing the industry toward buildings with minimal energy demand and related monthly costs. Recently, however, there has been a shift toward addressing the carbon footprint of the construction process itself. Wood, with its low carbon emissions, is emerging as a key player in this shift. As building codes evolve to permit greater use of wood, particularly mass timber, there is a significant opportunity to reduce the carbon footprint of construction.

In Europe, energy efficiency has long been a standard, and now low-carbon building policies are becoming more prevalent. Canadian cities like Vancouver and Toronto are following suit with initiatives to cut embodied carbon in new construction. Provincial and federal governments are also setting carbon reduction targets in their procurement practices, creating a ripple effect across the industry.

The Rise of Mass Timber

The past 15 years have seen a substantial growth in the mass timber sector in both Canada and the U.S. Building codes are increasingly recognizing the potential of mass timber products, which are now being used in structures previously deemed unsuitable because of their height and/or occupancy . Notable examples include Brock Commons/Tallwood House (Photos 1 and 2) , an 18-storey student residence at the University of British Columbia and the Fast + Epp Home Office Building, a mixed use, 4-storey infill building in Vancouver. These structures demonstrate the viability of mass timber in high-rise and hybrid construction, blending wood with other materials for enhanced performance.

The Importance of Collaboration

For hybrid buildings such as these, designers and specifiers must work closely with contractors and suppliers to ensure that material choices align with the project’s goals. By fostering collaboration, teams can leverage the expertise of various stakeholders, ultimately leading to more innovative and efficient solutions. The transition from traditional construction methods to a hybrid approach is reshaping the way we build in Canada.

Code Changes

Changes to building codes have been instrumental in this shift. For instance, the National Building Code now allows encapsulated mass timber construction (EMTC) up to 12 stories, with some jurisdictions permitting up to 18 stories. This increased acceptance is largely due to rigorous research by the National Research Council of Canada and other organizations, which has validated the performance capabilities of mass timber and engineered wood products.

Peter Moonen is National sustainability Manager for the Canadian Wood Council.

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January 3, 2020January 3, 2020

THE ROTUNDA

High-performance office building rejuvenates downtown neighbourhood

Occupying a prominent downtown corner across from Victoria’s historic City Hall, this mixed-use commercial complex includes two levels of underground parking, a street level with landscaped boulevards and public plazas flanked by ground floor retail spaces. The six-storey, 10,362 m² west building and 13-storey, 16,299 m² east building house class-A office space above.

By Franc D’Ambrosio, Founding Principal, Erica Sangster, Principal, D’AMBROSIO architecture + urbanism and Andy Chong, Managing Principal, INTEGRAL GROUP.

Urban Design and Architecture

The developer’s aim was to contribute to the resurgence of Victoria’s downtown, provide much needed high-quality office space and set a design benchmark in the regeneration of a moribund city block. The building forms have been sculpted to define street edges and create public spaces that are welcoming, human scaled, and integrated with both the street fabric and the building activity.

The fundamental massing strategy was to divide the site laterally and thereby locate two separate and distinct buildings. As a complex of two buildings, the project is in scale with the surrounding context. The separation has allowed for gracious public open spaces and also facilitated phased construction. The two buildings share aspects of form and materials, but differ in their massing and façade composition. Both outwardly express their function, with slender office wings and primary circulation routes clearly articulated in concrete and glass.

The public focus of the project is the Rotunda, a 500m² sky-lit atrium that brings natural light into the centre of the west building and also functions as the return air plenum for the ventilation system. To support the 20-metre diameter skylight, a unique structure comprising six ‘boomerang-shaped’ radially arranged, glue-laminated timber members was designed. The members are connected with steel tension rods, as well as concentric steel tension and compression rings – a solution that is economical in material use and maximizes daylight penetration.

Energy

The project’s Energy Utilization Intensity (EUI) was reduced by high-performance in three main areas: building envelope; ventilation heat recovery; and building heating and cooling. Building envelope options were optimized using energy modelling, and include a continuous layer of exterior insulation to achieve R-30 in walls.

Combined with high-performance double-glazing and a strategic window-to-wall ratio, the building enclosure minimizes both heat loss, and cooling requirements due to solar heat gains.

Heating and cooling for the building is driven by a hybrid air/ground-source heat-recovery chiller plant. This system can operate in either air-source mode (taking advantage of Victoria’s relatively temperate climate), or in ground-source (maintaining compressor efficiency, while using only a modestly-sized borehole field). Radiant ceiling panels provide heating and cooling to all office spaces, using moderate water temperatures and eliminating the need for fans to distribute space heating and cooling.

Ventilation

The larger east building uses underfloor air distribution and displacement ventilation. Dual core heat recovery technology reverses intake and exhaust pathways every 60 seconds, alternately charging large aluminum cores to achieve more than 80% effective heat recovery; much higher than conventional fixed-plate or wheel-type systems.

Variable speed AHU fans and automatic VAV dampers modulate the supply of dedicated ventilation air (no recirculation) in response to CO2 and humidity levels, maintaining indoor air quality and exhausting latent heat gains, while conserving energy for fans, heating, and dehumidification. All systems are controlled by a comprehensive digital Building Automation System.

PROJECT PERFORMANCE

Energy Intensity = 102 kWh/m²-yr
Thermal Energy Demand Intensity = 22.9 kWh/m²-yr
Energy Consumption Reduction vs. ASHRAE 90.1-2007 (LEED 2009) Baseline = 45%
Energy Cost Savings vs. ASHRAE 90.1-2007 (LEED 2009) Baseline = 33%

PROJECT CREDITS

Owner/Developer: Jawl Properties
Architect: D’Ambrosio Architecture + Urbanism
General Contractor / Construction Manager: Campbell Construction
Energy Model: Integral Group
Structural Engineer: RJC Engineers
Building Envelope: RDH
Landscape Architect: Murdoch & de Greeff
Electrical Engineer: AES
Mechanical Engineer Integral Group
Structural Engineer: RJC Engineers
LEED Consultant: Integral Group
Photos: Sama Jim Canzian

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January 3, 2020March 7, 2020

UBC AQUATIC CENTRE

Advanced sustainable design strategies improve performance in this challenging building type

Completed In 2017, this 8000m² hybrid competition and community aquatic facility replaces an aging indoor and outdoor pool complex, no longer capable of meeting the University of British Columbia’s changing needs. The challenge was to create a facility that would balance the high-performance training requirements of the university successful competitive swim program, with the increased demand for lessons and leisure opportunities from the rapidly expanding residential communities on campus.

By Jim Taggart

The Aquatic Centre is divided north south into four linear program ‘bars’ – lobby and change rooms, community aquatics, competition aquatics, and bleachers. Daylight is used to differentiate between the two aquatic halls. A line of Y-shaped columns supports a continuous six-metre wide skylight that bisects the aquatic hall, delineating competition and leisure areas. A translucent screen creates a luminescent barrier between the two principal spaces, making it possible to control the uses, and have two different activities or events taking place simultaneously.

The architectural composition consists of three distinct elements: a tessellated standing seam metal roof that hovers over an inclined black concrete base, and is separated from it by a continuous ribbon of fritted glazing. The roof rises and falls according to the functional requirements of the spaces below, its slopes and projections providing rain protection, solar shading, and control of daylight penetration as required. The building has become an integral part of the university’s new student hub, adjacent to the bus loop and a few steps from the new student union building.

As a building type, aquatic centres present some major challenges from the sustainability perspective, including water conservation, air quality, energy optimization, light control and acoustic performance.

Water Conservation

Of these, water conservation is the most significant, standard practice being that pools are emptied and the water discarded every time the pool requires maintenance. For the project team, not only did this seem an outdated practice from an environmental point of view, it also seemed incompatible with UBC’s reputation as a leading proponent of sustainable design.

In fact, water conservation has been an important consideration for the UBC Properties Trust for two decades, with new buildings now required to reduce water consumption by 30% relative to the reference standard. This is part of an overall requirement that all new projects are built to LEED Gold standard.

With the university currently conducting research on regenerative neighbourhoods, the project team began looking for ways in which the building could contribute positively to the infrastructure requirements of the community as a whole.

The answer was to create an underground cistern that could not only collect all the pool water during maintenance, but also supply the fire department should the need arise, or accommodate storm surge water for the north campus precinct, so relieving pressure on the existing storm sewer system.

The cistern, which has a capacity of 900,000 litres, is divided into three compartments according to the amount of filtration required prior to reuse. Another of its functions is to collect rainwater from the roof and the adjacent transit plaza, reusing it for toilet flushing, irrigation and poll top up.