Double Take

Research center innovates with double-skin façade, dual climate zones, and natural ventilation


By Christine Lewers

When Walter Bettio and a trans-Atlantic team of architects set out to design the Terrence Donnelly Centre for Cellular and Biomolecular Research on the University of Toronto's St. George campus, they wanted to create a space that would be as responsive to the needs of the people as to the work that would go on there.

Before researchers set foot in the building, fume-hood installers let him know they succeeded.

"They said they had never worked in a space that was as full of light as this building," says Bettio, associate-in-charge of the project with Toronto-based architectsAlliance, the firm that collaborated with Behnisch, Behnisch, and Partner Architekten of Stuttgart, Germany, to design the $93.4 million, 221,120-square-foot center.

The Donnelly Centre opened in November 2005 as a "greenhouse" for scientists to collaborate across disciplines for genetic applications of disease prevention and cure. It is a contemporary glass building, at once playful and elegant in its use of transparency and color, whose narrow 12 stories stand in contrast to the shorter, squatter brick buildings of Toronto's historic downtown section.

The building was conceived by scientists, for scientists, as a way for the university to build on the success of the Human Genome Project. As such it would stand as a tool for attracting top-level medical, engineering, and pharmaceutical researchers, says U of T's Capital Projects Director Nick Zouravlioff.

"The champions of the project were quite forward-looking," says Zouravlioff. Sure, they wanted a flexible, state-of-the-art research facility, he says, but they also wanted it to be open and full of natural light, qualities not found in most North American labs.

For the architects, says Bettio, the problem was how to provide naturally lit and open spaces without sending heating and cooling costs through the roof. They achieved their goal by designing a clever shell, importing a glass curtain wall system from Europe, and incorporating dual climate zones and natural ventilation into the design.

Painted, colored walls enliven the building after dark. PHOTO: Tom Arban

Clear the Clutter

By the very nature of the programs housed within its 100,000 square feet of lab space, architects knew the Donnelly Centre would be heavily mechanically saturated. The first issue: Where could designers locate heating and cooling equipment, as well as fume and lab exhaust systems, without blocking light and clogging spaces?

A compounding problem was the inflexibility of the build site, which was a long, narrow utility lane and parking area bordered on the east, west, and north by existing structures and to the south by College Street. Architects needed to build up, but such a narrow, vertical mass would look out of proportion next to the smaller buildings surrounding it.

Designers solved both problems by breaking the building mass into two rectangular boxes set atop each other and pinched at the middle by a windowless sixth floor. This floor and a 13th floor oval penthouse contain six of the building's mechanical air-handling units. A seventh unit is located on the entrance floor and serves the basement.

"If you went into the mechanical rooms, you'd understand" just how congested the building is, says Fred Kane, senior designer with H.H. Angus & Associates, the Toronto engineering firm that designed the HVAC system and its controls. He explains that massive amounts of ductwork are incorporated cleverly within eight vertical shafts that span the length of the building.

"But it's all hidden from site," except in the labs themselves where designers chose to nix drop-down ceiling treatments, exposing ductwork while adding to the airiness of the labs, says Kane.

With the mechanical systems tucked away, designers had more room to not only open up the lab space, but also include amenities like a first-floor atrium, naturally lit and easily accessible staircases, and a variety of informal gathering spaces and hanging gardens scattered throughout the building.


The building's main entrance is on the suth side, accessed through an exterior, granite-paved forecourt lined by historic buildings. PHOTO: Tom Arban


Glass Everywhere

A glass envelope lets daylight penetrate the offices and labs on floors two through five and seven through 12, providing scientists with the healthy natural light they wanted. A design challenge was how to keep occupants comfortable behind transparent glass without throwing energy efficiency out the window.

To prevent solar and thermal gains, the architects chose low-E-coated high-performance glass. Cardinal coated it and Prelco fritted, tempered, laminated, and manufactured it into sealed units. Aluminum extrusions by Kawneer and Ferguson Neudorf were thermally broken with a polyimide extrusion rather than PVC because of the material's superior insulating properties, says Bettio.

"The glass of the building is about as sophisticated as North American curtain wall systems can be. All four façades are very different and responsive to their immediate context," Bettio says.

The most cutting-edge use of glass is the building's south-facing double-skin façade, the first of its kind in a cold North American climate. A single layer of clear tempered glass comprises the outer weather envelope. Spaced 2.5 feet away from the outer layer is a second, inner thermal skin of argon-filled, thermally broken glazing. Space between the two skins provides a thermal buffer from temperature extremes outside and mitigates traffic noise.

"In Europe, double façades are widespread," says David Cook, partner-in-charge at Behnisch. "A double façade, correctly used, has distinct properties that can be used to improve comfort levels for building occupants and can also lead to substantial reductions in operational costs," although upfront cost are roughly 175 percent more than a double-glazed single-skin façade, he says.

Originally Cook's firm proposed a double skin for all four sides of the Donnelly Centre, but because of its cost and novelty, the university opted for it on the south elevation only. On this side, the offices of the center's principal researchers are from the second floor up.

Motorized dampers and vents on the outer skin connect to the building management system and work along with the natural stack effect created in the space to ventilate the cavity, which is compartmentalized from floor to floor.

Within each floor's cavity and placed closer to the external glazing are German-manufactured perforated retractable aluminum louvers with 4-inch concave slats. Nysan Shading Systems in Calgary custom-designed the blinds, which are programmed to tilt to prevent direct sun from hitting the inner glazing. Heat absorbed by the louvers is either captured in the winter or expelled in the summer by the ventilation system.

Nysan's BlindView software controls the louvers' slant. In the Donnelly Centre BlindView isn't integrated with the building management system, but it has the capability to be. It also allows for flexibility. For example, three winter gardens also reside behind the south façade. In these areas, blinds are programmed to let in more light than in the offices.

Each office has a wall-mounted toggle switch that lets occupants override the automated louver system. Operable windows on the inner glazing also allow occupants to let in the fresh, yet temperate, air of the cavity, even when it's well below freezing outside, says Bettio. However, when a window opens, the room is cut off from the mechanical system to prevent energy loss.

The trade-off is worth it.

"There are obvious psychological advantages in being able to open windows and effectively control your own environment," Cook says.

Glass floors within the cavity allow for maintenance and maximize the transparency of the façade. But concealing the conduit that supports the 120-volt louver system was a challenge, says Peter Rosteck of Commercial Vision, the Toronto firm that supplied and installed the blinds along with the software that controls them.

Rosteck says he worked with the glazing, electrical, and controls contractors to come up with a way to run wiring through the outrigger arms. "The architects wanted it looking clean," he says.

They got what they wanted.

From outside, the glass-over-glass wall gives the façade a sense of transparency and depth unusual in North American glass curtain wall systems, which often have reflective solar-block glazing. At 7 a.m. the center's BlindView automated control system sets the louvers to a uniform position, but as the day evolves, so does the façade to a more molted, almost disheveled look, says Bettio. The shades' shifting positions throughout the day reflect the sun's path as well as individuals' preferences for shade.

Glass doors within the double skin of the Donnelly Centre's south facade allow for maximum penetration of daylight into researchers' offices. PHOTO: Commercial Vision


Dual Climate Zones and Working the Stack Effect

The labs, too, have operable windows, explains Bettio, despite the fact that the mechanical system must work harder to keep temperatures constant.

To offset the higher energy use of the labs and offices, architects separated the climate control system of these areas from the public spaces of the building. In communal spaces they relaxed consistency standards for heating and cooling and dropped air changes to one or two per hour versus the six to seven required in the labs.

"The communal spaces are tempered with warm air that's not as comfortable as what's in your office," says Bettio. "You're not heating the entire building to the same level. You're heating spaces where people need to be warm."

Common spaces include the first-floor cafeteria, stairways, corridors, and one of the building's most striking features: a five-story atrium on the center's west side that greets people entering the building.

Nine operable windows in the atrium's skylights connect to the building management system. Management can open these windows along with the east-facing operable windows of the first floor's administrative offices to create a natural stack effect that, with mechanical assistance, ventilates the public spaces and saves energy.

Architects abutted the west side of the Donnelly Centre to the 100-year-old Rosebrugh building, restoring and claiming its buff brick façade for an interior atrium wall. The skylights above the wall are a laminated/tempered glass assembly with ceramic frit laid over the entire surface. The fritted glass blocks solar gain but lets daylight illuminate the Rosebrugh's façade, as it did before the research center went up.

The skylights also send light streaming through the canopy of the atrium's soaring giant-bamboo garden. Woodworkers reclaimed lumber from trees cleared for the building to make slatted, contemporary benches for the atrium, the cafeteria, and the building's three winter gardens.

Dangling out over the bamboo garden are open, shallow stairways leading up to the informal lounges and conference spaces that are just outside the building's second- through fifth-floor lab space.

With so far to look and so much to see, it's no wonder people don't notice the slightly less temperate air of the ground floor. But what about energy use?

After 1 year, it's too soon to tell how well the building's more innovative climate control measures are paying off, says Zouravlioff.

But for now, the building not only raises the bar for North American research centers, but it could also bridge the way for more sustainable climate control technologies to migrate across the Atlantic.

"Sometimes just one instance as innovator or indulgence, that's enough," says Bettio, referring to the building's south façade. "If everyone would perform one task we'd all be better off. Right?"

Open circulation stairways and informal meeting spaces promote collaboration among researchers across disciplines. PHOTO: Ben Rahn