Since the early days of the modern movement, discussions about glass in architecture have focused on the physical property of transparency and the evolving cultural meanings associated with its use. There’s no doubt that transparency will always be one of the most crucial and wondrous qualities that glass offers architecture, but there’s also no reason that today’s designers should limit themselves to exploring this single attribute.
As readers of IGS are well aware, advancements in glass technology have radically expanded thecharacteristics and capabilities of this material over the course of the 20th and 21st centuries, with emerging developments promising even more. At the same time, we have also arrived at a moment in which the urgent challenges facing our world – from widening inequality to climate change – demand that architecture find new ways of connecting with people and nature for mutual benefit. When we wield glass as a multifaceted material in service of this mission, what new trajectories for glass architecture become possible?
The design of Solar Carve (40 Tenth Ave), a commercial tower, offered my team at Studio Gang the opportunity to pursue this question at a prominent and highly unique site in Lower Manhattan. Located at the western edge of the city, its L shaped parcel is positioned between the clear expanse of the Hudson River and the elevated, linear High Line park, a former railway that is now one of New York’s most popular public green spaces.
These unusual spatial conditions set the stage for a building that could provide spectacular, unobstructed views and plentiful natural light and air for its occupants. On the other hand, it simultaneously threatened to block all of these same benefits for park-goers using the High Line. This is because New York’s zoning regulations maintain sunlight for the public way by requiring that tall buildings be set back from the street as they rise upward – but inthis case, it was not the street but the innerblock park that needed protecting. Following the as-of-right massing would have meant creating a tower that stepped up toward the High Line, throwing its green space into shadow for much of the day and obstructing visitors’ view of the river.
Rather than accept these conditions, our project team sought and received a zoning variance for a solution that benefits both building users and the public by inverting the prescribed setback. The resulting sleek, sharply faceted tower draws on a range of glass technologies – from low-e coatings to heat strengthening and bird-safe frit – to enhance the environment within and beyond its envelope. At the same time, its gem-like form demonstrates the striking visual potential of treating glass as a sculptural material that can be cut at the building scale.
Deferring to the space of the High Line, the design strategically shifts and stacks the tower volume to the west (toward the Hudson) to open up greater access to sunlight and fresh air for park-goers. The incident angles of the sun’s path and other parameters are then used to “carve” the slender building mass at its southeast and northwest corners, allowing additional sunlight, air, and river views for the High Line. A faceted glazing system articulates the curved carve surfaces as a geometric pattern. Iterative design and quantitative daylight analysis, conducted in consultation with Arup, led our team to the final tower form, which allows more than three times as much sunlight per year to reach the High Line compared to a conventionally massed, rectilinear tower. This not only provides a healthier environment for the people who use the elevated green space but for the vegetation and wildlife that live there, as well.
Shifting the tower volume to the west also allows for an expansive 10,000 sq ft (929 m2) terrace to be created at level 2 atop the building’s podium. Like the park that it borders, this terrace is designed to support a range of uses and biodiverse plantings that benefit from the sunnier environment. More opportunities for building users to enjoy the outdoors are provided by a shared 8,300 sq ft (771 m2) green roof deck atop the tower and by private corner terraces on most levels that extend beyond the faceted façade.
Inside, the ten-story tower’s slender floor plates permit natural light to completely penetrate the office levels. Locating the core off-axis, rather than in the center of the floor plate as is typical, allows for open floors that can flexibly accommodate various uses. The carved areas at the corners are dimensioned and configured to preserve a flexible plan while bringing a bespoke spatial experience to the interior, accommodating a range of uses from conference rooms and individual offices to animating an open office layout.
To achieve the design, our Studio Gang team worked closely with curtain wall manufacturer and engineer Focchi and structural engineer and façade consultant Arup to design and engineer two major custom curtain wall systems that are attached to the building’s reinforced concrete structure. Both systems are double-glazed and use low-e, low-iron glass manufactured by Interpane. The result is a high-performance façade with very low reflectivity that furthers the design intention to be a good neighbor—reducing energy use as well as allowing for clear views between the Hudson River and the High Line; reducing glare for drivers, cyclists, and pedestrians along the adjacent West Side Highway; and decreasing the risk of bird deaths due to collisions with glass they cannot see.
The first curtain wall system, used for the majority of the enclosure, employs flat curtain wall units with a standard dimension of approximately 5 feet (1520 mm) wide by 16 feet (4870 mm) high. This is the full floor-to-floor height, and from inside the office floors, the dramatic effect of this large expanse of glass is heightened by eliminating knee walls to allow for unobstructed views outward. Each double-glazed unit consists of a heat-strengthened pane on the outside and a tempered, monolithic pane on the inside. The glass used to clad the building’s typical floors (levels 2 through 10) is coated with low-e Interpane Ipasol neutral 38/23, which fulfills the LEED Gold-certified project’s energy performance goals while also reducing glare and improving bird safety as mentioned above. At the ground floor (level 1), where more transparency was desired for the retail spaces on Tenth Avenue, the low-e coated glass used is Interpane Ipasol neutral 70/37. All of the system’s aluminum profiles are powder coated in a custom dark grey, compliant with AAMA 2604 for interior profiles and with AAMA 2605 for the exteriors, to visually thin the mullion width and to harmonize with the color of the High Line’s steel structure.
The second glazing system is used to enclose and articulate the “carves” at the building’s northwest and southeast corners. Its three-dimensional, faceted curtain wall units are each made of five double-glazed panels: a central, diamond-shaped panel, which is angled downward at 24 degrees, and four surrounding triangular panels that are perpendicular to the floor slab to achieve traditional stack joints. This assembly is designed to provide multiple benefits. The tilted panels reduce solar heat gain by self-shading, while the total units are sized for efficient transportation via shipping container and truck, and to optimize construction by being easily staged on-site and lifted into place by a crane truck. Each unit has a base of 5 feet x 5 feet (1520 mm x 1520 mm) with a typical height of 16 feet (4870 mm) to span the full floor-to-floor dimension. Both interior and exterior panes are laminated for safety and have the same Interpane Ipasol neutral 38/23 coating as the flat portions of the typical floors. The aluminum profiles are powder-coated in the same custom dark grey, completing visual consistency with the rest of the façade.
The texture created by the carve units is also a bird-safe design element that supplements the low reflectivity of the glass. Its “visual noise” alerts birds to the presence of a solid material, and the downward-angled panels reflect the ground rather than adjacent habitat or the sky above, further deterring collisions. These strategies extend the design’s care for its surrounding environment to encompass wildlife as well as people. Up to 1 billion birds currently die each year in the United States due to striking clear or reflective glass they cannot see. Studio Gang has long been a leader in addressing this issue, working with ornithologists, activists, and organizations such as the New York Audobon Society to develop and advocate for bird-safe strategies that support avian life. With Solar Carve’s proximity to the shoreline on a major migratory pathway, it is particularly critical that its architecture incorporate these measures.
A final strategy, smaller in scale but deployed in a key location, is the fritted glass used for the wind screens on the roof terrace. These tempered glass panels improve the comfort of the roof garden’s human users while also
looking out for the health and safety of avian visitors. Applied to the glass as a thin film, the frit pattern is only lightly visible to the human eye but is perceived by birds as opaque, alerting them to fly around the screen rather than through it. This is especially important because the roof garden’s native vegetation and elevation makes it an otherwise attractive place for birds to land and forage.
As New York continues its latest building boom, Solar Carve provides a site-specific counterpoint to the many object-like buildings that have sprung up along the High Line and elsewhere. Working at multiple scales, and with multiple properties of glass, its architecture demonstrates how density can be added to the city in a sensitive way that helps to enhance its surrounding environment. Respecting and protecting our shared public assets does not have to limit design—it can in fact spur exciting new directions.
This article was originally published in IGS Magazines Summer 2020 USA Special Edition: Read the full Magazine here for more thought-leadership from those spearheading the industry
More thoughts and projects from Jeanne Gang on taking glass architecture “beyond transparent” are included in Studio Gang’s new monograph, Studio Gang: Architecture, out now from Phaidon Press: phaidon.com/studiogang
American architect Jeanne Gang, FAIA, Intl. FRIBA, is the founding principal and partner of Studio Gang, an architecture and urban design practice headquartered in Chicago with offices in New York, San Francisco, and Paris. Understanding architecture as a practice of relationship building, Jeanne is renowned for projects that connect people with their communities and the natural environment. Her award-winning body of work ranges from cultural centers (Writers Theatre) and civic projects (Chicago River Boathouses) to high-rise towers (Aqua). Current projects include an expansion to the American Museum of Natural History in New York City; the new United States Embassy in Brazil; and the Global Terminal at O’Hare International Airport. The author of three books on architecture, Jeanne is a Professor in Practice at the Harvard Graduate School of Design and the only architect named one of TIME magazine’s most influential people of 2019.