Shaping Skin

Aesthetics & Performance of Non-Planar Facades, and the Circadian Curtain Wall





The conventional modern facade is essentially flat, which creates the tendency toward visual monotony and problems for modulating daylight—both on the surface, as shade and shadow, and as it enters the building through fenestration. A side of a rectangular building either faces the sun or doesn’t at any given time of day, and the need to have shades deployed to block glare and heat eliminates all views on a face of the building for some period. This interferes with visual connection to the outdoors, awareness of the circadian variability of natural light, and with offsetting artificial lighting and related energy use with indirect daylight.

Recent non-planar facades on high-rise buildings seem to reflect a desire to revive the texture and detail of early modern skyscrapers’ bay windows and classically derived ornament. Architects and developers justify the complexity of non-planar facades featuring non-repetitive projecting windows by pointing to captured views and enhanced connections to the outdoors complemented by self-shading, reduced solar heat gain and daylight autonomy. But functional advantages seem to be secondary to the marketing benefit of singular appearance and identity, with projects usually having seemingly random forms in relation to exposure. Aesthetically, the topographically varied, shaped facade creates sculptural interest, and suggests the classical references of architecture to the living human figure. The trend holds potential for realizing a level of sustainability in high-rise facades impossible with the flat orthogonal wall, but so far the potential appears to be largely unrealized due to the primary motive of attention-getting appearance.

This paper describes the analysis of a lobed bay-window scheme for a high-rise office tower facade incorporating a closed cavity system with automated shades—the Circadian Curtain Wall--, and frames further systematic study of a set of examples of non-planar facades to assess their potential benefits. The further studies will evaluate the closed cavity prototypes in terms of daylighting autonomy, self-shading to reduce heat gain, embodied energy related to intrinsic structural properties of surface, life cycle assessment of added cost versus improved operational performance, and the advantages-- including economy-- of maintaining flat facets of shaped surfaces.

Introduction: Shaping Skin

We shape clay into the form of a vessel; but it is where there is nothing that the efficacy of the vessel lies. - Lao Tze, The Tao, Chpt 11.


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Background: Shaped Skins

Double-skin facades and sunshade structures have created building surfaces with depth in many different contexts for a long time. The shaping of surface in the way that the early modern

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The Circadian Curtain Wall

In early 2018 a team of HOK volunteers and I, with assistance from WSP Built Ecology, developed a concept for an ideas competition, sponsored by the New York Steel Institute

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To prove out the concept, Elliot Glassman of WSP Built Ecology created an integrated energy and daylighting model of a typical floor to analyze the benefits of the design. Studying

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The resemblance in plan of the lobes of the Circadian plan to a leaf or petals of a flower—or a brain-- creates a biomorphic quality that reinforces the connection to

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Circadian Curtain Wall Project Team:

John Neary, HOK Facade Architecture

Michael Miller, HOK

Zhenhuan Xu, HOK

Blake Kurasek, HOK

Marie Achabalun, HOK

Mario Claussnitzer, HOK Facade Engineering

Matt Breidenthal, HOK Structural Engineering

Elliot Glassman, WSP Built Ecology

with extra help from:

Apoorv Goyal, Sustainability Specialist at HOK

Victoria Ereskina, Facade designer at HOK

Shaping Skin bay studies, design and modeling:

Victoria Ereskina

Rights and Permissions

J. Neary & HOK/WSP team, “Circadian Curtain Wall,” Finalist, Metals In Construction 2018 Design Competition.

J. Neary & HOK team, “Structural eXterior Enclosure,” Finalist, Metals In Construction 2017 Design Competition. Program based on paper by J. Neary “Structural Skin: Integrating Structure and Cladding,” Facade Tectonics Institute, October 2016.

J. Neary “Structuring Skin: Patterns of Integrating Cladding and Structure,” Facade Tectonics Institute, March 2018. (Accessed 2018-10-25).