The World's Top Five Ecological Skyscrapers
Monday, October 25, 2010
Here is an in-depth look at the world's top five existing ecological skyscrapers. These architectural masterpieces are excellent examples of ways that modern building techniques can both reduce energy consumption and at the same time remain attractive.
Today's ecological skyscrapers belong to an emerging area of design research in which the environmental impact of the building and issues of sustainability influence every scale and system of a tall building. Recent concerns with environmental issues have prompted skyscraper designs that employ a range of strategies to conserve energy, minimize buildings' impact on their surroundings, and ensure that the building materials used to construct them will be recyclable in the future.
A few design firms are taking the lead in this area of design research, designing buildings in which the design's success or failure is determined by its relationship to the environment.
Conde Nast Building (Fox and Fowle, New York, 1999)
Built as part of the renaissance of Times Square, the Conde Nast building is also the first ecologically designed North American skyscraper. AT the time of its construction, high-rise buildings rarely addressed environmental issues. Today, many of its innovations are considered standard for office buildings.
A monumental catalyst for the ear, this is the first office building to be developed by the 42nd Street Development Corporation, a public/private consortium established to promote the redevelopment of Times Square. Located on the corner of 42nd Street and Broadway, the Conde Nast building straddles the glitzy Times Square entertainment area to the west and the corporate Midtown area to the east.
Designed with two distinct faces, the west and north facades respond to Times Square with the glitter and technology of metal and glass, while the east and south facades respond to the corporate context with a historical stone façade, creating, according to the architect's description, a “marriage of pop culture and corporate dignity.”
At street level, the tower's lobby, with its dramatically curved ceiling, connects 42nd and 43rd streets, drawing visitors through the building. Responding to the Times Square zoning ordinance, the building's base is covered with billboards and neon sign age.
This building sets new standards in energy conservation, indoor environmental quality, recycling systems, and the use of sustainable materials. The large glazed-glass areas of curtain wall maximize daylight penetration. The curtain-wall glazing incorporates a low-E coating to filter out unwanted ultraviolet light while minimizing heat gain and loss. Photovoltaic panels are integrated in the spandrel areas on the upper floors of the east and south faces, generating a meager but symbolic amount of electricity by day.
Sophisticated mechanical systems ensure high indoor air quality by introducing filtered fresh air to the office environment. Tenant guidelines produced by the architects established environmental standards for lighting, power usage, furniture systems, carpet, fabrics, finishes, and maintenance materials to ensure indoor air quality, and also to serve as a comprehensive strategy to maintain environmental sustainability for the life of the building.
This pastiche of environmentalism, historicism, futurism, and commercialism creates a complex architectural organism. Indeed, the arguments for energy conservation seem out of place in a neighborhood like Times Square, which is predicated on a spectacular excess of energy-consuming visual pyrotechnics. A difficult first in the realm of ecological skyscraper design, it anticipates the next generation of ecologically sensitive North American skyscrapers.
Deutsche Post AG (Murphy/Jahn, Bonn, 2001)
This sleek tower housing the new headquarters for the Deutsche Post is exemplary of a kind of sustainable design practice that achieves the goal of environmentally sensitive architecture without sacrificing aesthetics or occupant comfort. The tower rethinks the skyscraper as a building type by focusing on the integration of function, technology, and user comfort to create an architecture of “high technology and low energy.”
The tower is made up of two curved semicircular masses connected by glass bridges. The connecting floors, at nine-story intervals, form atrium sky gardens which are naturally ventilated and serve as interior communal spaces. A skylight annex houses additional public spaces at the base of the tower, and is clad in a “smart skin” of glass and integrated photovoltaic panels.
The façade design consists of a twin shell glass curtain wall. The clear glass outer shell allows for natural ventilation, and protects from rain, wind, and noise. The operable inner shell allows occupants to control the local interior climate. Floor to ceiling glazing optimizes daylight penetration and reduces energy consumption through the reduction of interior lighting, while integrated sun shades in the façade cavity control heat gain during periods of direct solar exposure. As the architects point out, the building's roof and façade are no longer surfaces with constant properties, but rather a highly specific system of interchangeable parts that allows the building to adapt to changes in temperature, humidity, light intensity, or acoustics. The architects describe the multi cell roof as “the technical equivalent of the biological skin.”
The building employs an integrated heating and cooling radiant-slab system, taking advantage of the thermal storage capacity of concrete. Additional heating and cooling systems assist with interior climate-control during summer and winter months.
Utilizing a computerized building management system, the building monitors its climate and controls all of the components to optimize its “operational mode.” The intelligent building creates its own equilibrium with the exterior environment through constant feedback. Careful monitoring reduces redundant lighting and conditioning, providing these only as required, and significantly reducing operating costs.
The collaboration between Jahn and Sobeek produces what they call “archi-neering,” a seamless integration of architecture and engineering design. The design for the Deutsche Post building achieves new levels of design integration with technology, in order to create smarter and more responsible architecture. Jahn describes this environmental optimization by stating, “Nothing must bed added, and nothing can be taken away.”
Adia Headquarters (Kohn Pederson Fox International, Abu Dhabi, 2004)
The curvilinear headquarters building for the Abu Dhabi Investment Authority (ADIA) combines a sensuous formal vocabulary with a low energy design strategy appropriate to the Middle Easter climate. The building mass is draped in a glass curtain wall that folds in and out of the tower, transforming from the taut skin of the exterior envelope to the inner liner of the internal atrium.
The building is sited in a green fringe of the city, close to the sea. Its curved form gestures to the waterfront on the west, with elevators and other services concentrated on the east. The tower consists of two wings connected by an elevator core and a setback atrium. The building mass is camouflaged by the undulating ribbon like surface that projects above the tower, culminating in a sail like projection on the north façade.
The curtain wall consists of a double façade of clear glass that admits natural light and air while cutting down on the amount of solar heat gain. The taut glass skin transforms on the west façade with the introduction of horizontal sun-shading devices. The interior atrium is conceived as a series of stacked sky-gardens that act as passive means to regulate humidity and temperature, as well as contributing to a sense of community.
The architects describe the form of the tower as a “rethinking of the tall office building in a changing cultural, social, and environmental context.” The organic form of the tower seems to be derived from a concern with the fluid forces in the context, rather than a rigorous internal logic. Indeed the curvilinear geometry of the floor departs from conventional space-planning modularity. The combination of bold sculptural form a sensitive environmental systems makes the tower a benchmark in the ecological design of the skyscraper.
RWE Headquarters (Ingenhoven Overdiek und Partner, Essen, 1996)
The glassy RWE Tower in the predominantly low-rise city of Essen, Germany, stands out due to its slender proportions and light materials, as well as its role as a pioneering work of sustainable design. Designed by the firm of Ingenhoven Overdiek und Partner, the tower utilizes sophisticated building systems, allowing it to consume less energy while still providing a comfortable, naturally lit and ventilated interior environment.
The cylindrical tower is sited in the middle of a landscaped park, surrounded by a lightweight pergola structure that defines the street edge. The tower itself consists of two volumes, the cylinder housing the office spaces and an adjacent elevator tower. The cylindrical plan allows all the offices to be located at the perimeter, guaranteeing access to natural light and air, while a service core and conference rooms occupy the center.
A “breathing double façade” system allows the occupants to benefit from natural light and air, without adding to the cooling and heating loads of the mechanical systems. The curtain wall is made up of a compartmentalized double layer of floor-to-ceiling glass. The outer layer is formed by a taut skin of low-iron glass with an innovative horizontal mullion, which acts as an airflow valve and ventilates to the exterior. The compartments are accessible from the inside via sliding-glass doors, allowing occupants to control the amount of fresh air let in.
The building-management system monitors exterior climate data in relation to the interior temperature, and makes adjustments accordingly. Mechanized sun shades are integrated into the façade cavity and automatically raise or lower to control heat gain on the façade. Exterior sensors warn occupants to close their windows when it rains, or if it is particularly windy. Other systems allow for harvesting energy from roof-mounted photovoltaic panels.
Ingenhoven Overdiek und Partner describe their design criteria as “efficiency, ecological consciousness, economy of resource usage, and build ability.” The RWE Headquarters is an example of an integrated-systems building that pioneered new technologies in façade design, energy efficiency, and sustainable materials. Its “smart-façade” system addresses the apparent conflict between thermal conservation and daylight illumination through the use of clear glass and integrated mechanical systems.
110 Bishopsgate (Kohn Pedersen Fox International, London, 2005)
110 Bishopsgate is part of a new generation of high-rise buildings approved for construction in the City of London. The environmentally sensitive and structurally articulated tower is expressive of the technologies that enable it.
The project is located on the eastern edge of the old city, on a prominent site at the junction of Bishopsgate and Chamomile Street, and across the street from the Georgian church of St. Botolph. It forms part of a cluster of office buildings that includes the NatWest Tower and the 30 St. Mary Axe. The recent crop of office buildings in London corresponds to a demand for large floor plates to provide flexible office space in the center city. It also responds to the evolution in expectations of what a contemporary office building should be with regard to the working environment that it creates and the approach to energy consumption and sustainability.
A perimeter service core on the south organizes the building, allowing open plan offices to benefit from exposure to the west, north and east. The service core acts as a buffer against solar exposure to the south, while allowing for continuous and unobstructed working spaces on the north side. Responding to the technical and social demands of the modern workplace, the building is organized as a vertical armature of flexible spaces.
Office spaces are clustered around multistory atria that the architects call “villages,” allowing tenants flexibility in renting either a single floor or multiple floors connected by internal stairs. Other amenities include retail and restaurant spaces at grade and a public restaurant at roof level.
The east and west facades, clad in clear glass, allow occupants to control the amount of fresh air ventilation, while reducing the amount of solar heat gain in through the glass. The building's structural skeleton is expressed on its north façade, framing the atria.
Designed by Kohn Pedersen Fox International, the firm's London office, 110 Bishopsgate represents the translation and adaptability of the high-rise office building type to central London and the implementation of demands for flexible space as well as environmental sensitivity.
Honorable Mention:
The Hearst Tower, New York City
Hearst Tower is the first building to receive a Gold LEED certified rating for "core and shell and interiors" in New York City. The structural steel in the construction contains over 90% recycled material and 50% of the tower's water usage - for the cooling system - comes from a 14,000 gallon rainwater tank.
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