Canadian Consulting Engineer

Feature

Telus Sky Tower

In Calgary a new tower is rising 58 storeys to transform the city skyline with a distinctive curved and textured facade.


From the December 2016 print issue, page 14

Artist’s rendering of the Telus Sky Tower in downtown Calgary, with its “pixelated” wall formed by irregular protruding balconies. Image: BLG/DIALOG.

Under construction in the heart of downtown Calgary, the Telus Sky Tower will be the city’s third tallest building when completed in 2017. The 58-storey, 221-metre structure will be shorter only than the Bow, which was completed in 2012 at 237 metres, and Brookfield Place which is also currently under construction at 247 metres.
Located at the 7th Avenue and Centre Street, the Telus Sky tower has a distinctive profile that narrows as it rises and has a distinctive “pixelated” façade on the north and south sides. Architects Bjarke Ingels Group of Copenhagen and DIALOG of Calgary have designed the building to curve and incline on two different arcs roughly at the point where the building changes from office to residential floors. In addition, the smooth glass cladding on the lower commercial floors transforms into a three-dimensional composition of protruding apartments and balconies in the residential suites above.
There are seven levels of below grade parking, three floors of commercial and retail uses, then 28 floors of office space. The floors above consist of 326 residential suites. The lower floors will include a restaurant, health club and 5,500 sq.ft. public amenity space.

STRUCTURAL ENGINEERING – Unique Geometry
By Anthony El-Araj, P.Eng., Glotman Simpson
The structural framing of the tower’s unique geometry of pixelated expression and slab terracing required attention in order for the structure to function seamlessly within the multi-use spaces. We achieved this by avoiding interior columns, and instead placing them around the perimeter, making them equally spaced to match the pixelation bays.
At 58 storeys, the tower’s 3.6 length-to-width ratio also made it susceptible to cross wind dynamic accelerations that could exceed occupancy comfort levels. Also, since the terracing is not uniform along the north and south faces, it imposed a structural twist or torsion. These issues are resolved through the lateral load resisting system. We designed a unique shearwall layout for the entire building that provided adequate stiffness and strength for the induced loading demands from both the wind and the horizontal thrust loads of the “walking” columns. The shearwalls included walls that framed the elevator bank on the office levels, and wing walls that sit on columns below.
At the tower’s parking levels, we used ultra-high strength concrete, 110 MPa, and composite structural steel and concrete columns to reduce the size of the structure and maximize the number of parking stalls in the tight space provided.

MECHANICAL ENGINEERING – District Energy and Displacement Ventilation
By Jason Edey, Reinbold Engineering Group
The office portion of the tower is being designed for LEED Platinum certification. It is estimated to consume 30% less energy than similar buildings.
The office and residential component are both connected to the Enmax District Energy System. District energy systems are inherently efficient because of their scale. This one serves buildings in the East Village district and downtown Calgary, distributing hot water through underground pipes in a closed-loop system to heat exchangers in the individual buildings.
The tower’s office floors have displacement ventilation systems, where ventilation air is supplied from central heat recovery air handlers that supply tempered fresh air, and recover heat from stale exhaust air. The ventilation air is fed through underfloor plenums to two-pipe cooling-only fan coil units, then rises by convection through floor diffusers into the space. The system gives maximum thermal comfort to the occupants and minimizes noise. Architecturally an underfloor system allows for clear ceilings with maximum height and more efficient lighting.
The ventilation air is ducted directly into individual zones, where sensors manage the air flow and indoor air quality — all connected to a central building automation system. Thermal losses at the exterior of the building on the office floors are addressed by specially designed VAV perimeter hydronic radiation troughs that are installed flush with the raised floor system.
The residential suites have four-pipe horizontal fan coil units with ECM motors that meet the heating and cooling loads, while reducing fan energy during partial loads.
Rainfall will be collected from the level 60 roof and re-used for the roof top gardens. The rest of the building — including the suite balconies — will have the storm water piped internally to a storage tank in the parkade, a practice which is not typical in the city of Calgary.
Grey water will be collected and treated for use in the urinals and water closets up to level 6 on the commercial floors, all helping to reduce the water use.

ELECTRICAL ENGINEERING – One Backbone, Added Intelligence
By Gary Rhode, Integral Group
We were tasked with integrating all the building systems into one communications backbone. The systems can then be controlled and synchronized through a central building automation system (BAS) to achieve maximum energy efficiency and effectiveness.
Good design for mechanical and electrical systems is not enough any more; without good information on what is happening in the building, decisions cannot improve. The vision for the Sky Tower is to have all systems connected for real time information and control. Reaching this vision requires adding analytics or intelligence to inform the operator and occupants what they need to know about the performance throughout the building’s useful life.
Integrating systems in this way requires the design team disciplines to collaborate and integrate their designs from the beginning. This project has buy-in from the owners down and we believe the approach will maximize the comfort of its occupants.
The building has many other sustainable features, such as the lighting system, which is all LED and uses addressable lighting controls. Half the roof area supports a PV solar array that produces 32,000 kWh/yr and feeds directly into the building’s power systems. On the other half of the roof is a landscaped garden surrounded by high glass walls.cce

Telus Sky Tower Design Team
    Owner-client:    Westbank Projects
    Architects:    Bjarke Ingels Group and DIALOG
    Structural:    Glotman-Simpson (Anthony El-Araj, P.Eng.)
    Mechanical:    Reinbold Engineering Group (Edward Lazar, P.Eng.); Allstar Mechanical Group (Jeff Wilson)
    Electrical, energy     Integral Group (Gary Rhode, Ali Nazari,
    modelling, LEED     Kevin Welsh)
    Supplier:    Armstrong Pumps (pumps)