If not theEuropean headquarters of KPMG, 15 Canada Square could have been just another box. Before the accounting and professional-services firm, one of the four largest in the world, agreed with developer Canary Wharf Group to take ownership of this metropolitan London office, Kohn Pedersen Fox Associates’ (KPF) base building design had not included the atrium that runs the full height of the 15-story tower. Nor had KPF conceived the signature three-story “cassettes” that march up the building’s southwestern corner. The original building had more of a traditional lobby without atriums; the cassettes were designed by KPF in response to KPMG’s needs.

“It changed from a spec office building to a specific program for work, education, and client reception,” says KPF managing principal Paul Katz. KPMG encourages cross-disciplinary work, with members of different divisions seated side by side, so four cassettes—upper-story atriums that connect three-story blocks of offices by stairwells off of an 11-story atrium—foster collaboration at a large scale. In another example, the main atrium includes a coffee bar on the ground floor before security, allowing in-person client conversations to take place without protracted security check-in. The distinctive features such as the transparency provided by the multiple atriums also broadcast KPMG’s ethos to the public.

The cassettes’ stairwells also lessen elevator usage, and indeed, KPMG requested a more sustainable building than the building’s developer had intended. “They are the most environmentally aware client I’ve worked with,” says Angela Sasso, the London-based director of commercial interiors for Swanke Hayden Connell Architects (SHCA), which KPMG retained for the interior fit-out. KPMG had developed a sustainability management plan in consultation with the British organizations the Carbon Trust and the Waste & Resources Action Programme, and the plan not only included its Building Research Establishment Environmental Assessment Method (BREEAM) ambitions, “but also recycling content in the building, aspects of waste management, noise—it went far beyond the standard, ‘Let’s just get the certification.’ ” When it opened in May 2010, 15 Canada Square had secured BREEAM Excellent ratings for Design & Procurement, Post Construction Review, and Management & Operation. In the UK-based sustainable assessment system, a building can receive rankings of outstanding, excellent, very good, good, pass, and unclassified.

Yet the client also insisted on a balanced ledger, “which is why you don’t find PV cells on the building. Payback was something like 275 years, whereas payback on chilled beams was a more sensible 25,” Sasso says.

As an integrated team, the designers did the math on myriad technologies’ performance and amortization, and presented the findings to a steering committee and the KPMG board. “We went through a whole process of verifying the installation and operation costs of the most efficient systems,” Katz explains. “As eventual owners of the building, KPMG wanted to achieve a sustainability goal, but within a specific budget.”

In addition to those chilled beams, the finished product includes smart-building management that can adjust room temperatures according to body heat. Another 25-year investment is a trigeneration unit that produces gas-fired electricity on site, and whose waste heat is used for building heating or cooling. The system will help cut 15 Canada Square’s carbon dioxide emissions by 20 percent against 2006 building regulations and by half against the KPMG buildings it replaced, and KPF principal and project manager Shawn Duffy says that commissioning thus far confirms performance projections.

Taken individually, 15 Canada Square’s sustainability strategies are competitive in the regional marketplace, and they are becoming increasingly common as a result. “You can incorporate economically and technologically feasible strategies without compromising the overall design,” Duffy says. Features such as the ventilated wall cavity and 15-story atrium are well-suited to London’s temperate climate. A sedum roof controls runoff from London drizzles, while graywater recycling, which reduces water consumption by approximately 40 percent, places less stress on municipal infrastructure. Other moves, such as the interior fluorescent lighting, make sense anywhere: “LEDs’ intensity and color output just aren’t there yet,” Sasso says of the sourcing decision. Perimeter sensors adjust the lamps’ intensity according to daylight levels.

KPMG proved a valuable research partner to KPF and SHCA in turn. For years it had scrutinized how staff occupies space, finally determining a blended desk-sharing ratio of 1:1.4. That figure represents a big swing, from 7:1 in the case of the on-the-go auditing team to the tax department’s 1:1 rootedness. Besides justifying Sasso’s open and mobile office workspace, the data allows for more intensive use of the interior design. At opening, the building included 2,800 desks for 4,000 staff, and the addition of 500 employees beyond that has required no extra furniture. Sasso explains that typical buildings are utilized at 50 percent capacity; at 15 Canada Square that figure is 80 percent. This represents a shift in sustainability metrics, from Btus per square foot to consumption per capita, and the forecast for the building is even more favorable should the company consolidate employees from its office still operating in Salisbury Square. That lease expires in 2015.

Yet another metric that the designers cite is 30, the average age of KPMG employees. That would explain the mobile workspaces or the conversion of one floor of underground parking to 200 bike pods with changing facilities: Employees these days like to work and commute these ways. This also justifies KPMG’s race to sustainability in general. In addition to ultimately saving money, facilitating an internal culture, or projecting a positive image to the public, sustainability wins the hearts of young talent.

David Sokol writes about architecture and design from New York and Washington, D.C.