Oriented along the building’s North South axis, the iconic ventilation tower rises to mark the splay of the east and west tower masses and the main entry. A dynamic pattern transitions from metallic bronze at the base of the tower to metallic blue at the top, interspersed with vertical silver fragments, and is intended to symbolically mimic the movement of air up the shaft. The transition between light and dark blue alludes also to the flow of water that is the primary source of Manitoba Hydro's power. Several options for the cladding were explored before a final combination of colour, sheen and pattern was selected. At 15.5m long, 2.85m wide and 119.0m tall the solar chimney shaft begins at the parking level and extends to 115.5m above grade. Its composite aluminum cladding uses a 500 wide x 2000mm high module with 3 distinct colours and 2 sheens (a matte and gloss) to create its unique image. This cladding conceals a thick layer of mineral fibre insulation that surrounds the exterior extent of the tower helping to reduce heat loss in winter as the air travels down to the parkade.
The solar chimney’s main mechanical function is to marshal the exhaust air to suit the seasonal, energy and life safety requirements of the building. Exhaust air collected in the North Atrium from the office floors enters the solar chimney through its louvered south face. A series of vertical and horizontal dampers, controlled through the Building Management System (BMS) discretely turn selected dampers off and on to create separations within the concrete shaft that compartmentalize and guide the exhaust air out of the building. In winter this air is pulled down by fans to the parkade for heat recovery, while in summer and natural ventilation modes the air is drawn up by natural stack effect to exhaust through the automated glass louvers at the top level of the chimney.
Two planes of black, powder-coated steel pipe are positioned just inside the steel framing at the top of the solar chimney that store solar energy in their thermal mass. Each plane, comprised of 5 rows of vertically oriented 125mm diameter steel pipe (46 pipes per row), is positioned to optimize morning and evening solar collection. Each pipe is completely filled with sand to further enhance its storage capacity. The solar thermal mass collector extends the natural ventilation seasons for the building by maintaining higher temperatures at the top of the chimney, and thus a natural stack effect, even when the temperatures outside of the building drop below functional levels. Low-iron content glass (for both the curtain wall cladding and the glass louvers) optimizes solar heat gains into the top chamber of the tower where a solar mass thermal collector is positioned to aid in the natural exhaust of air from the building during shoulder seasons (spring/fall) and summer.
Related Performance Goals:
Energy Performance-Sustainable Design
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