Winnipeg Millennium Library
March 1, 2006
By Canadian Consulting Engineer
"A lot of effort was put into re-using the existing building infrastructure," says Elliott Garfinkel, P.Eng. of MCW/ AGE of Winnipeg. The company was the electrical engineering consultant for the Winn...
“A lot of effort was put into re-using the existing building infrastructure,” says Elliott Garfinkel, P.Eng. of MCW/ AGE of Winnipeg. The company was the electrical engineering consultant for the Winnipeg’s Millennium Library renovation in the city’s downtown on Donald Street, near the MTS Arena. “It’s easy to strip out and start from new,” Garfinkel adds, “but it’s way more challenging to build upon what’s existing. A lot of time was spent on that.”
The original library, known as the Centennial Library was built in the 1970s. It was the typical massive concrete “bunker” seen throughout cities in Canada from that date.
The architects for the expansion, Patkau and LM Architecture, decided to radically open up the building to the exterior by removing the entire southeast wall that faces a park. In its place they added a huge glass walled reading terrace that expands across and up to the full height of four floors allowing daylight to flood into the building.
An entire new fourth floor was added to the three existing floors as well, so that in total the expansion added 40,000 square feet to the existing 140,000 square feet. The renovated library opened last fall.
The structure of the original building was already designed to sustain the addition of a fourth floor. However, structural engineers Crosier Kilgour and Partners had to build new foundations for the glass addition along the southeast wall. Perhaps the most interesting aspect for them was helping the architects design the unique steel frame to support the glass wall in the terrace. Stretching 220 feet long and 84 feet high, the frame consists of a series of vertical trusses, each of which is unique. The library’s stepped floors extend into the steel frame structure, so the occupants can sit and study beside the window, within the frame.
Hydronic heating and cooling
SMS Engineering had to modify the existing heating and cooling system to accommodate the new fourth floor as well as the new glazed southeast terrace.
The glazing for the terrace wall is an energy efficient triple glazing with a Low-E coating. The architects wanted to minimize the solar gain, but did not want to obscure the daylight with mirror or tinted glass.
Stirling Walkes, P.Eng. of SMS Engineering, the mechanical engineers, says the terrace is a complex space for heating and cooling because of the proximity of the glass. The temperature on the glass surface in winter, for example, might be 10C below the interior space temperature, creating uncomfortable cold spots. At the same time, solar gains are substantial and can create a sauna effect, both in winter and summer.
Consequently, whereas the main floors are served by conventional air units combined with perimeter radiators, the terrace area has an underfloor hydronic heating and cooling system. The 12-mm in-floor tubing is a cross-linked polyethylene with an oxygen barrier. Water in the hydronic system is circulated year round. The heating plant warms it in winter, and in summer a plate heat exchanger provides an interconnection with the chilled water system. The slab temperature is controlled according to the outdoor air temperature. For example, when the outside temperature is -40C, the slab is at 30C; when the outside air is 10C the slab is 20C, and at 35C outside temperature the slab is 15C. The slab temperature during the cooling season is monitored to ensure it does not drop below the air dewpoint, which would cause condensation on the floor surface.
Like the terrace, the fourth floor addition is also conditioned separately from the main floors. It has an underfloor air distribution system served by a new dedicated air handling unit. The air is distributed by grilles at floor level in the 30-ft. high space. The air is supplied at approximately 17C, which is 4C higher than a conventional air supply system, meaning that the system can use free outdoor air cooling more often.
Boilers and chillers
A new condensing boiler was added in the heating loop to inject heat prior to the two existing boilers. The condensing boiler receives the coolest return water temperatures, thereby maximizing its efficiency and serving to protect the existing 879 kW natural gas water tube boilers from thermal shock. The total capacity of the heating plant is now 2,314-kW, with the condensing boiler providing 556 kW, mostly during the shoulder seasons.
An existing chiller that used R-11 refrigerant was replaced with a 385-ton dual compressor unit that uses R-134a, a more environmentally friendly coolant. The dual compressor unit has a smaller fooprint and increased efficiency. It had to be installed in a new chiller room attached to the existing fourth floor mechanical room, which was formerly on the rooftop.
Since the project had a limited budget of $20 million, it was fortunate that the 1970s building had features that readily lent themselves to the renovation. For example, the original building had been designed for electrical heating, so MCW/AGE were able to use the existing power supply of 1,500 kVA and the distribution system and build upon their capacity for the upgrade. They replaced a generator in the existing electrical room in the parkade as well as the fire protection, security and other systems. They had to add an entirely new data and communications infrastructure, which they did by threading it through the existing electrical risers into ceiling spaces and coring up into the floor above.
Wherever possible the existing lighting was retrofitted and reused. On the first, second and third floors, T12 fluorescent fixtures were changed to T8s (the replacement process had already begun before the renovation). In the glazed reading terrace with its ample daylight, task lighting in the study carrels is combined with T5 linear fluorescent lighting that is carefully integrated into the high black ceiling. — BP
Client: City of Winnipeg Planning Property & Development, City of Winnipeg Library Services
Structural: Crosier Kilgour & Partners (Kelly Hearson, P.Eng., Kathy Pratt, P.Eng.)
Mechanical: SMS Engineering (Helmut Waedt, P.Eng., Stirling Walkes, P.Eng., Rick Penner, Trenton Lalonde, Randell Estoy, Jeff Corrigal)
Electrical: MCW/AGE Consulting Professional Engineers (Elliott Garfinkel, P.Eng, Gary Davey)
Architect: Patkau Architects/ LM Architectural Group
Project Management: Man Shield Construction
Suppliers: Simplex Grinnell (fire/security); Caterpillar (emergency generator)