Building-Integrated Shading

Beyond Sun Block: Innovative shading solutions not only provide protection but further architectural expression.
 
Sponsored by Draper, Inc. and Phifer Incorporated
Architectural Record
By Katherine Logan
 
1 AIA LU/HSW; 1 AIBD P-CE; 0.1 IACET CEU*; SAA 1 Hour of Core Learning

Learning Objectives:

  1. Discuss shading strategies that can strengthen a building’s architectural identity.
  2. Explain how the shading schemes discussed in the article help save energy while maintaining occupant comfort.
  3. Describe the modeling, simulation, and analyses that helped produce each of these shading schemes.
  4. Define technical terms relevant to shading, such as “SCC” and “insolation.”

This course is part of the Daylighting Academy

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By the time solar radiation hits an interior blind, the fight to save energy has been lost. The great advantage of exterior shading devices is that they block the heat outside, before it can penetrate the building envelope. Depending on their design, they can also improve daylighting by reducing glare and bouncing indirect light deep into interior spaces. They can even strengthen a building’s identity. But North American construction culture has been slower than that of many other countries to embrace exterior shades.

IMAGES: © BEN RAHN/A-FRAME (TOP AND BOTTOM LEFT); COURTESY HARIRI PONTARINI ARCHITECTS (BOTTOM RIGHT)

ALL WRAPPED UP
The renovated Jackman Law Building (top) is animated by vertical shade fins. Within the reading room (bottom left), the fins are continued as white-painted pilasters that act as vertical light shelves.

From the 1990s until quite recently, architects on this continent often envied the textured and articulated building envelopes their international counterparts were creating, while their own shade designs were regularly stripped in cost-cutting rounds. As energy conservation has become a top priority, however, and integrated design teams with access to increasingly sophisticated modeling tools are able to quantify the benefits of shade, those sad old days are receding. Building envelopes in North America are now incorporating shading that is as inventive and expressive as anything architects here might once have envied.

Exterior shades’ best chance of surviving the process euphemistically known as value engineering is to serve more than one goal. The Jackman Law Building, by Toronto-based Hariri Pontarini Architects (HPA) and B+H Architects; the John A. Paulson of Engineering and Applied Sciences, by the Boston office of Behnisch Architekten; and the Kendeda Building for Innovative Sustainable Design, by Lord Aeck Sargent (Atlanta) in collaboration with the Miller Hull Partnership (Seattle), exemplify a new generation of shading-integrated exterior envelopes that do more than keep their cool.

For the Jackman Law Building, a 2016 renovation and addition to the University of Toronto’s Faculty of Law, the challenge was to unify the school’s disparate and organizationally disjointed pieces, built over a span of nine decades, and to give it a physical expression commensurate with its institutional significance. The brief included recladding and renovating a library, and creating new classrooms, offices, and gathering space. Says Siamak Hariri, principal at HPA, “The need for shading gave us a way in, to do something that gives an order and a presence to the entire building.”

Located on a prominent site with five major frontages, the irregular building’s new and renovated parts are wrapped in a simple rhythm of vertical shade fins. (Because the building has almost no exposure due south, vertical shades are an effective solution.) Executed in local limestone, the fins make multiple references, from the columns supporting the portico of the school’s neoclassical main facade, built in 1902, to similar fins on the courthouse a few blocks south, and, metaphorically, to the pillars of justice.

In response to client concerns about whether the fins would block too much light, HPA conducted comprehensive daylight studies. The architect relied primarily on physical models, supplementing them with digital simulations, to prove the concept to their clients and to themselves. The fins’ 2-foot depth and 5-foot-on-center spacing is informed by these analyses—and by the need for an office-friendly module—as is the 18-inch depth of white-painted pilasters on the library interior. The latter act as vertical light shelves, mitigating glare and reflecting light more deeply into the space.

The choice of stone for the shade fins stems from an aspiration to counter a look of mindless mediocrity that Hariri sees being inflicted on cities by the widespread use of ersatz materials. Imitations lack the dignity, patina, and subtle variety of natural materials, he says, and he advocates for beauty as a value in its own right, as well as for its contribution to durability: “A really good building is one that people will not let be taken down.”

There’s still the immediate reality of cost, however, and the project budget of $42 million had no room for extras. Working closely with the supplier, HPA designed a shop-fabricated assembly that brought stone into the price range of its precast-concrete competitor. The fins are built up with straight sections of limestone clipped to a steel armature that is suspended from the slab edge (with careful detailing to mitigate thermal bridging). Rather than appearing as solid, which the natural variety of the panels precludes anyway, the fins are designed to express their assembly, with reveals at panel joints. The underside of the armature is closed with a bronze metal plate, and the section of the stone cladding is visible from the street below.

Within the shade fins’ uniform rhythm, the thermal envelope syncopates in response to the programmatic requirements and the facade’s different exposures. A play of glass and metal cladding balances the wall-to-window ratio for energy performance, and the double-glazed units incorporate their own type of shade with a spectrally selective coating. (SCC reflects the infrared, or heat, segment of the solar spectrum while admitting a higher portion of visible light.) The SCC on the interior surface of the outboard lite has a bronze tint to complement the stone, while a low-E coating on the exterior surface of the clear inboard lite further improves the glazing’s ability to shield against solar gains.

IMAGES: COURTESY BEHNISCH ARCHITEKTEN

LACE VEIL
At Harvard University’s SEAS (bottom), a textured screen of 48,000 hydroformed stainless-steel brackets (top left) will dissolve the large building’s apparent mass.

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Originally published in Architectural Record

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