X/O Skeleton

Roosevelt Island, NY

Workplace Government Science & Technology

X/O Skeleton exterior view

The knowledge that the embodied energy of a building can far exceed its lifetime energy usage demands an innovative response of materials and systems. How light can buildings be? Inspired by natural formations and the potential of high-tech materials, the design proposes a new way of thinking about high-rise façade construction – one that minimizes the structure’s embodied energy, as well as its lifetime energy use. 

The “X” refers to the diagrid system, an optimized structural form which efficiently combines lateral and gravity loads at the perimeter of a building. The team sized the diagrid to create a column-free environment, maximize views, and serve a secondary function as the primary backup for building cladding.

The “O” represents pillow-like infill panels of ETFE (Ethylene tetrafluoroethylene), a fluorine-based plastic that serves as the primary weather, thermal, and solar control layer. Because ETFE presents technical challenges, the team proposed a composite wall system incorporating transparent nanogels and aerogels. While plastics are high in embodied energy, their relative weightlessness compared to glass makes them an order of magnitude better on a square foot basis and has added benefits of reducing weight, the cost of shipping and construction, and the eventuality of recladding.

Design Evolution

The guiding concept for our hybrid structure-skin system was influenced by the natural form of the exoskeleton, which is simultaneously rigid, protective, multi-functional, adaptive, and responsive. Our lightweight solution achieves a 75% reduction in the embodied energy and embodied carbon (psf) of the building facade. Beyond performance metrics, we focused on a solution that was flexible enough to be replicated in a variety of different building configurations and simple enough to be a viable replacement for the traditional curtain-wall system.

Innovation Building Performance

We were inspired by natural organisms like coral reefs, where the exoskeletal structure supports a dynamic and environmentally responsive soft tissue.

Jason Olsen Jason Olsen, AIA, LEED AP BD+C Lead Designer

Further Reading

More Projects Like This

Birch Bayh Courtroom

General Services Administration

Birch Bayh Federal Building & US Courthouse

Indianapolis, IN


Birch Bayh is a model citizen, serving its city in ways its original designers never could have imagined.

exterior detail at dusk

General Services Administration

William S. Moorhead Federal Office Building

Pittsburgh, PA


The new façade and interior upgrades reinvigorate the GSA workplace brand, making office space more attractive to potential tenants.