Architect Corner
Wood, Water and Air By Nick Bevanda
CEI’s submission for the office building of the future.
O
ver the past few years, architects in British Columbia have been exploring opportunities to increase the use of wood in the built environment. There are several reasons for this shift, including strong government support through the Wood First Act and the many environmental benefits of the material, such as its ability to sequester carbon dioxide and the fact that building with wood requires less overall energy than other materials. Plus, it’s visually appealing, providing inherent warmth to interiors and visual interest to exteriors. As a result, members of the design and construction industry are increasingly experimenting with wood products and approaches. When NAIOP, the commercial real estate development association, announced a competition inviting architecture firms to design “the office building of the future,” CEI Architecture, along with a team of engineers, took a bold approach, designing a landmark 40-storey facility predominantly comprised of wood and possessing exceptional energy efficiency. CEI’s submission confronts the debate about how high the industry can build with wood. The firm’s submission proposes a 40-storey wood tower that is iconic in design and attractive for potential tenants, for many reasons. As the firm that designed the groundbreaking Centre of Excellence in Sustainable Building Technologies at Okanagan College in Penticton, a facility targeting net-zero energy and water use, CEI was able
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to incorporate many innovative measures for environmental sustainability.1 Additionally, CEI was recently selected as the indicative architects to work with Partnerships BC on the Wood Innovation and Design Centre in Prince George, exploring the use of wood outside of traditional building code standards. CEI recognized that such a tall building constructed from 100 per cent wood has height limitations. A smart alternative is to combine wood with other materials in a hybrid fashion, minimizing concrete and steel as the primary support and emphasizing wood for secondary structural systems. With this in mind, the goal was to maximize the use of wood and propose innovative systems as a commitment to environmental sustainability, ultimately delivering comfortable office and work spaces that have lower rental costs, fit-out costs and ongoing operating expenses. The scheme proposes a building footprint of 150 feet by 90 feet, with a central concrete core. Floor decks are made of wood-concrete composite elements that take advantage of the superior tension capacity of wood and the compression capacity of concrete. The choice of composite also has acoustic benefits. Floors are constructed from engineered CREE panels, spanning 30 feet from the core to the perimeter truss. An eastwest axis helps maximize solar gain and control east-west exposure. Exterior sunshades are oriented vertically on the east-west elevations, with horizontal shades on the south that incorporate photovoltaic solar panels. Wood trusses with depths matching the 12inch floor-to-floor heights are efficient structural elements and placed at the perimeter of the building at every alternate floor. The top and bottom chords of the trusses support the floor decks that span from core elements to the perimeter. The ability to support two floors with one trussed level allows the building to have clear span sky garden or sky lobby at chosen levels. The wood trusses are engineered using locally harvested wood; their visual presence contributes to a warm, inspiring work environment and also becomes the primary architectural expression for the building.
Four concrete piers, 30 feet from the end, are strategically positioned at building perimeters to support the wood trusses with cantilevers to achieve further structural efficiency by minimizing internal forces. Reinforced concrete is used for its structural properties of strength, rigidity, ductility and continuity, to resist lateral forces such as earthquakes and wind. The mechanical design would feature a variable air volume (VAV) system. A central air handler provides conditioned air at 12 C to every zone in the building. At the zone level, a VAV box modulates the airflow to control cooling. For perimeter zones, the VAV box also contains a reheat coil that can reheat the supply airstream to provide heating capacity during the heating season. The unique design allows the water and wastewater systems to be configured into four zones of 10 storeys each. Greywater collected from sinks and other non-toilet waste fixtures is piped separately from toilet blackwater and flows by gravity to the floor level of the outdoor decks for drip irrigation of vegetative plantings, such as living walls. These landscape areas consume 100 per cent of the greywater via plant evapotranspiration. In other words, no greywater is discharged to the city’s wastewater system. Occupants get to enjoy lush vegetated areas at each of the 10th floor interval levels — a pleasurable connection with nature. CEI Architecture’s preliminary costing has shown this scheme can be constructed with a five per cent savings over traditionally constructed office buildings, an indication that innovative building approaches featuring substantial, sustainable and smart use of wood is an approach worth considering. Nick Bevanda, Arch. AIBC, MRAIC, AIA, NCARB, is a partner at CEI Architecture. He brings a wide variety of experience both within the public and private sectors. 1
e Case for Tall Wood Buildings, By Michael Th Green, MAIBC, FRAIC