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Solution of the Month:

Ventilated in Vancouver

Perkins+Will and Stantec
Vancouver, British Columbia

Take a tour of this research centers natural-mechanical ventilation hybrid.

By David Sokol
July 2014
Photo © Don Don Erhardt

The Centre for Interactive Research on Sustainability (CIRS) is an initiative of the University of British Columbia that focuses on accelerating adoption of green practices in the built environment. Its investigative domain is as diverse as the field itself, with tasks ranging from analyzing government policy and documenting green-building occupant behavior to creating a video game that teaches players about resilient city planning.

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What every effort has in common is not only a mission of widening sustainability, but also a place of origin. CIRS’s multiple academic, nonprofit, and other partners work together and separately in a 61,000-square-foot building of the same name. Located on the University of British Columbia’s Point Grey Campus, the idea behind the building actually predates the program filling it: In 2000 John Robinson, today the university’s associate provost of sustainability, proposed creating a building for the school to use as a proving ground of cutting-edge sustainable design.

Robinson worked closely with an integrated design team whose members included Perkins+Will and Stantec for architecture and mechanical engineering, respectively. The cooperation of these partners is reflected in the orchestration of sustainability solutions. Photovoltaics are embedded in the 4-story atrium’s skylight, in order to shade the lobby space from beating sun productively. In a similar example of piggybacking, a heat-recovery system captures waste heat from the nearby Earth and Ocean Sciences building’s laboratory exhaust, and then transfers it through heat pumps to radiant slabs and perimeter radiators at CIRS; a geothermal field with 30 bore holes also supplies three heat pumps with heat in winter, and channels excess interior heat deep into the earth during the summer.

The air carrying this heat flows through the building thanks to a combination of natural and displacement ventilation—which represents a particularly multilayered convergence of systems and scales of thought. In the case of the natural system, the U-shaped building features narrow floorplates, in order to maximize cross-ventilation. To expedite that movement, moreover, the atrium lobby functions as a thermal chimney.

The atrium lacks mechanical ventilation altogether, points out Alberto Cayuela, CIRS’s director of operations and business development. “It’s all dependent on the stack effect,” he says, and the atrium’s hydronically heated slabs work in tandem with openings in the curtain wall and with operable rooftop vents to enable the effect. Cayuela adds, “Return air from the [flanking] north and south blocks, which contain offices and labs, is dumped into the atrium, as well. So although there’s no movement of air by fans or other equipment in the atrium, the return air facilitates convective movement.”

Cayuela explains that elsewhere in the building, mechanical ventilation runs for much of the year via an underfloor air distribution (UFAD) system. Supply air flows mostly through UnderFloorSox fabric ductwork installed within an 18-inch-high ventilation plenum, and then distributes through floor diffusers that require 25 percent less fan horsepower than distribution via conventional overhead air mixing ducts. “Underfloor air requires supplying relatively little static pressure to the plenum,” Cayuela says of this energy-efficient method, adding, “We’re not providing active cooling; for the most part we’re heating the building with underfloor radiators that are located along the building perimeter.”

One of two centralized air handlers in the basement’s mechanical room provides this air to each floor’s UFAD plenum. The second air handler supplies CIRS’s 425-seat Modern Green Development Auditorium, which employs an underfloor metal air distribution system manufactured specifically for theaters by Krantz Kompenten. Another point of contrast: the auditorium uses mechanical cooling through heat pumps that reject heat into the geothermal field.

“The auditorium is a different situation altogether,” Cayuela says. “Although we can naturally ventilate that space, 425 bodies can make it quite hot and concentrate carbon dioxide. The only other places where we have active cooling are unoccupied—the data rooms and electric vault.”

In the auditorium, a Honeywell building automation system (BAS) identifies various triggers like ambient temperature, and coordinates air movement and active cooling accordingly. Beyond that hall, the BAS orchestrates the interaction of natural and mechanical ventilation. When 30 percent of the windows in a particular building zone are open, or when a zone is unoccupied, the BAS makes sure that hot-water valves to those underfloor radiators are turned off; the BAS also communicates with variable frequency drives in the dedicated air handling unit, so that they supply even less static pressure to the plenum. “If conditions allow it, the building can fully rely on natural ventilation, such as during shoulder seasons and most of the summer,” Cayuela says.

Just as Robinson had imagined it, CIRS is being treated as a living laboratory. When asked to evaluate the hybridization of mechanical and natural ventilation systems, Cayuela admits that the lab results aren’t fully in yet. “There are two concerns here,” he says. “One is that there is a lot of uncertainty around the modeling for natural ventilation, whereas mechanical ventilation is much more predictable. Secondly, there is not a lot of precedent in how to study the effectiveness of the hybrid. Because we’re interested in figuring out the performance gap between design and reality, we’re trying to determine how to link our performance improvements to, say, lighting savings versus natural-ventilation savings.”

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