by Philippe Honnorat
A high-level assessment of the impact of the urban tower on the natural environment would conclude that low land use and possible higher density are the chief advantages, with high energy usage being the chief disadvantage. Concepts of density and of energy usage are relative, and should be examined by comparing high-rise buildings with their low- or mid-rise alternatives.
Under closer scrutiny, towers do, of course, make other positive and negative environmental contributions; but the number of these, and the interaction among them, is a highly complicated subject. We will therefore focus on some key elements, with the aim of providing a glimpse into the complex web of parameters influencing how an urban tower interacts with its environment, and how a tower can ultimately be considered sustainable.
The Principal Issues
The main questions of a technical and environmental nature to be addressed when contemplating a specific tower project and its urban implications go beyond land and energy use to encompass subjects such as access, transportation, construction challenges and technology. Many of these issues relate both inwardly to the tower itself and outwardly to the surrounding environment and urban context.
For instance, energy use can be influenced by a variety of factors, such as facade technology, local methods of energy production, international leasing market expectations, local construction and maintenance practices, and shading from surrounding buildings, to name but a few. The resulting complex interactions make each tower a one-of-a-kind project that strikes a particular balance among many factors.
And even before a tower project gathers momentum, its genesis typically precedes these project-related interactions with other forces at work, of a socioeconomic, political, and aesthetic nature — forces that continue to have a bearing throughout the project's life cycle.
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The Norddeutsche Landesbank complex (2002) in Hanover, Germany, designed by Behnisch Architekten, comprises a 20-story central tower at the center of a rectangular courtyard enclosed by a perimeter of low-rise wings.
Photo: Martin Schodder/ © Behnisch Architekten
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The primary courtyard entrances to the Norddeutsche Landesbank complex occur at the northwest and northeast corners, where the lower floors of the low-rise perimeter buildings were omitted.
Photo: Christian Kandzia/ © Behnisch Architekten
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