Inside the concave curtainwall on the Bow’s southern façade, a series of vertical atriums runs up the building’s full height, separating the offices from the exterior. The void acts as a natural solar-heat collector, creating a buffer of sun-warmed air that helps keep occupants cozy. In the winter, heated return air escapes from the adjacent offices into the atrium and rises upwards. “As the air goes up,” explains Cosentini’s senior vice president Scott Ceasar, “it warms up [further] from the sun. Then we capture it at the top.” The captured exhaust, prior to its discharge, is run with intake air from outside through a heat exchanger and heat recovery unit, “preconditioning” the fresh air that is then pumped down a series of risers into air towers on each floor and back into the offices. As a result, less mechanical energy is required to warm the airflow.
In the summer, Ceasar says, “It’s just the opposite.” The atrium acts as a spill area to draw in the cool, used office air, which is then warmed by solar radiation. The heated air stratifies upward to the top of the building where it runs through the heat recovery unit and partially pre-dehumidifies the incoming air. As the return air exits the building, the intake air is pumped into the air towers, cooled, and distributed into the offices, creating a continually refreshed stream of consistently comfortable air on every floor. The process of natural convection, combined with the preconditioning system, reduces the energy needed to intake and regulate the temperature of air by mechanical means alone.
At the individual office level, the conditioned air reaches building tenants by way of displacement ventilation through a subfloor installation that helps guarantee clean, high-quality air and a controlled temperature. F+P had used a similar raised-floor plenum approach in its Commerzbank project, channeling warm or cool air into the offices under the feet of occupants. “The underfloor system is not unusual for Europe,” Barnes says.
Indeed, the system’s relative scarcity on these shores is strange, given its inherent advantages over ceiling-mounted vents: Rather than pressing down against the warmed air’s tendency to rise upwards, floor-supplied ventilation moves it in a natural current that provides more air to more interior space. At the same time, airborne contaminants that cling to the ceiling aren’t constantly pushed back into circulation. The raised-floor plenum also provides more local control within each office to suit the preferences of individual workers. The practice of enabling users to create a comfortable work environment extends to the windows and window shades facing the atrium, which can be opened and closed at will.
Giving a human touch to the Bow’s technical achievements was another significant focus of the design collaboration. The entire organizing principle of the tower is geared towards humanizing it, breaking down its massive size to people scale. Envisioned as 10, six-story stacks—with the exception of the top and bottom stacks, which comprise five stories each—the Bow functions as a series of what Carruthers terms “neighborhoods … a very strong metaphor that plays out in a very real way in this building.”
Express elevators stop at select floors, from which workers transfer to local elevators just as they might switch buses or trains in an urban context. Each “block” is distinguished by a color-coded wayfinding system that takes its cue from the Alberta landscape and incorporates the particular hues and textures of the natural features visible from the windows of each respective floor. The intended effect of these buildings-within-a-building is that each component will act as a community of its own, with intrafloor mingling encouraging co-workers to exchange names, words, and ideas.
Perhaps the most important feature of the user-centric approach is the sequence of indoor gardens—landscaped sky lobbies—that create the aesthetic and social centerpieces of the interior arrangement. This, too, has become a hallmark of F+P’s work of late—similar gardens appear in its Frankfurt project as well as in an upcoming tower in Huangzhou, China. Jutting into the atrium on the 24th, 42nd, and 54th floors, the Bow’s sky gardens will offer some relief during the gloomier winter months and provide a dose of greenery that may help stave off seasonal depression in an area where many people are accustomed to starting and ending their workday when the sky is dark. Large planters filled with indigenous flora, an array of sustainably sourced furniture, and amenities such as coffee shops and eateries create a series of village greens within the building’s community-centered scheme.
The close-knit-neighborhood feel connects the Bow to the rest of Calgary, integrating the structure into a broader urban network organically. Linked to the city’s 10-mile-long +15 Skywalk system of enclosed, above-ground walkways, the tower can be entered and exited without ever having to set foot outside, encouraging visitor activity between the downtown’s developments throughout the months of single-digit temperatures. A light-rail transit stop is located just one block to the south of the building, and bicycle racks—more than 200 of them—allow workers to commute using nearby routes along the scenic Bow riverfront.
Projections of just how effective a building such as the Bow will be are still a matter of conjecture. The field of occupant wellness and its complex points of contact with overall sustainability is still a relatively new one. “The question is: How do you make people more productive?” Manno says. “We’re just now starting … to get more metrics. People are measuring things I’ve never seen them measure before.” Gensler has implemented a Workplace Performance Index to assess the effect of the various efficiency-improving initiatives on many of its other projects, but a host of unknowns still exists industrywide.
However, the Bow does represent a clear expression of the design profession’s emerging language of health and welfare, drawing on a growing vocabulary of sustainability that has become more mainstream in the past decade. The years to come will reveal how well architects learn to speak in this idiom, and whether what they have to say will translate into truly healthier and happier places for the people.