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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