The Devon site is at the southern edge of the central business district — a strategic position for the city's growth. Early in the process of site selection Devon projected that future growth would likely be to the south, and that a site on the southern edge of the CBD could position it at the center of the future Oklahoma City.
This strategy was validated in 2006 when the city adopted a plan to develop approximately 750 acres from the current downtown core to the shore of the Oklahoma River. The Devon site is at the northern edge of the plan.
Most of the existing site was covered by a large two-level parking structure. Adjacent to the Devon parcel on the same block are several office buildings, a vintage hotel to the east, and to a public library the northwest.
As the site design evolved, the 54-story office tower was located on the east side of the site, while such functions as a restaurant, meeting areas, conference and training facilities, and record storage were to be housed in a low-rise, horizontal wing to the west. An auditorium for large company presentations was broken out as a free-standing element to anchor the southwest corner.
Devon's public rotunda space — an important civic gesture from the beginning and part of Devon's gift to the city — occupies its own special spot at the heart of the complex.
'A Proud and Soaring Thing'
More than a century ago Louis Sullivan wrote that the tall building must be a "…a proud and soaring thing…" The result here is an indelible mark on the city skyline and the state's horizon: it became the tallest building in Oklahoma while still under construction, and it fits Sullivan's description.Pickard Chilton considered the shape of the tower with interior designers (Gensler), its structural engineer (Thornton-Tomasetti), and mechanical systems consultant (Cosentini Associates).
Conventional floor plates were studied, but they were too directional (square or rectangular) for a tower that would be seen from 360 degrees. Instead, the building's unique floor plate of approximately 27,000 square feet was designed based upon an equilateral triangle.
Devon's brownfield site, with links to public transportation and preferred parking spots for fuel-efficient and low-carbon-emitting vehicles helped the new headquarters to earn a LEED-NC Gold rating (it is currently the largest LEED Gold-certified building in the state).
The development's big-picture goals included maximizing daylight for a welcoming work environment that also helped employees be more productive; an energized downtown site to promote higher density and diverse uses; and economic development in an under-utilized part of town.
The form of the tower helps to equalize the solar load, which helps to make cooling and heating more efficient. Air distribution is through a raised floor system, which makes changes to office layouts easier to accomplish and boosts air-flow efficiency.
The balance of the heating, ventilation, and air-conditioning systems help to reduce carbon dioxide emissions, and more than half the building's occupants can personally adjust climate controls.
The building's ample sunlight reduces energy consumption, aided by daylighting controls — such as occupancy sensors — in the perimeter spaces. 90 percent of the occupants have personal control of lighting in their workspace.
In terms of sustainable water management, low-flow fixtures and other conservation measures cut water consumption by 40 percent, while green roofs aid on-site water management (they also help reduce the building's heat-island effect). Drought-resistant plantings and on-site water collection reduce the use of potable water for landscaping by 50 percent.
The sustainable role of materials was given special attention: recycled (27 percent) and regionally sourced varieties were specified, along with those with low-VOC emissions, rapidly renewable material content, and wood from FSC-certified sources (nearly a third of the wood used).
Waste material management was a priority as well: tens of thousands of tons of concrete were diverted from landfills, some of it used on-site for erosion control. Thousands of tons more of parking garage demolition waste materials were used by the Oklahoma Department of Transportation in state highway construction and maintenance. Hundreds of tons of metal from demolition were recycled.
According to architect Jon Pickard, one of the biggest advantages of the modified equilateral triangular plan is the breadth of views and sense of orientation achieved on every floor. "When you exit the elevator lobby, one is literally on an axis that orients views back to the city," explains Pickard.
The curtain wall of high-performance clear glass with a low reflectivity coating maximizes the amount and quality of daylight admitted through the floor-to-ceiling vision glass, while also reducing heat gain. The reflectivity of the spandrel glass matches that of the vision units, unifying the glass surfaces.
The brushed aluminum curtain wall frame includes stainless steel accents that render a gilt sheen across the tower's surface. Glass fins on the curtain wall climb the entire height of the tower, enhancing the building's vertical thrust and offering significant solar shading resulting in energy savings.
A Garden Wing
A complement of meeting areas, conference rooms, training facilities, compact storage, and food services are housed in the garden wing, which stretches from the rotunda entrance to the site's western edge. Beyond the functional needs, the wing achieves some essential urban design goals.
To the north, the site is populated with existing parking garages. Stretching over the south face of one of the garages, the garden wing effectively makes it disappear. The wing's southern exposure provides excellent daylighting.
Spending some time in these spaces reveals that they have just the right amount of filtered light and views of Devon's south-facing garden plaza to engender an interesting mixture of calm and sensory stimulation. The curtain wall design here is similar to the tower, with floor-to-ceiling glass and stainless steel accents to provide a woven enclosure.
Circle of Civic Engagement
The tower and garden wing are joined architecturally and spatially by arguably the most important urban element in the design: the rotunda. It signals "arrival" at Devon. Illumination is the key to the rotunda's architectural quality — not only as a bottle of sunlight, but in its structural expression.
A series of 16 radial trusses made of diagonal tubular steel elements and tension cords span 120 feet from ground level to the tip of the rotunda walls. The composition offers a surprising lightness and transparency.
Four circular walkways rise like halos through the space, lacing the trusses together. The first walkway is part of the rotunda's public space, and the deepest ambulatory, with a translucent glass floor that filters sunlight into the ground floor.
This walkway creates a shelf over one's head on the ground level, as one moves into the rotunda space and around it. The pedestrian feels compressed until one reaches the inner edge. The rotunda space then soars over one's head, buoyantly embracing the four stories above.
A space of this magnitude, especially one that is public, is not typically found in corporate headquarters. The best views in the rotunda (out to the city and from the center point of the space up to the tower) are accessible from the public realm, not from a privileged spot only for employees. It's a gift to anyone who enters Devon's new headquarters.
Architect Michael J. Crosbie is chair of the University of Hartford's Department of Architecture, editor-in-chief of Faith & Form magazine, and a contributing editor to ArchitectureWeek. This article is adapted from the forthcoming book, DEVON: The Story of a Civic Landmark, to be published by Images Publishing Group.
Located at the southern edge of the Oklahoma City central business district, the Devon Energy Center overlooks a southern portion of the city that is expected undergo urban revitaliztion in coming yeras. Photo: Simon HurstExtra Large Image
At the base of the triangular tower a circular ring of columns inscribes a space that intersects with adjacent circulation and touches the edge of the Devon Energy Center's rotunda. Photo: Simon HurstExtra Large Image
The facade of the Devon Energy office tower is expressed as three freestanding glass prisms attached to a central glazed core. The prismoid elements have slight entasis from base to top. Photo: Simon HurstExtra Large Image
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