The Council on Tall Building and Urban Habitat’s 9th World Congress came to a close today in Shanghai. Themed the “Age of the Sustainable Skyscraper City,” the sold-out, three-day event brought together over 800 of the world’s leading tall building owners, developers, contractors, architects, engineers, planners, and policy-makers to ask the question: is the skyscraper a sustainable building type? Discussions ranged from the technical aspects of energy consumption and carbon performance, to the social impacts on cities and inhabitants by pushing skyward.
Mic Patterson, Director of Strategic Development for Enclos, traveled to the CTUBH World Congress in Shanghai to speak about the need for facade retrofits of the early generations of tall buildings. Patterson’s presentation, entitled New Skins for Retrofits: Anticipating Facade Retrofit, occurred on day one of the proceedings and establishing both the problem and opportunity presented by the aging stock of tall curtainwall buildings.
Experts estimate that as much as 70% of the existing building stock suffers from underperforming facades. The facade, in mediating between inside and out, plays a primary role in performance, and building performance has now been widely recognized as a major sustainability issue. Buildings consume more energy than any other sector, nearly as much as the industrial and transportation sectors combined. According to Architecture 2030, a non-profit, non-partisan and independent organization established with the goal of reducing greenhouse gas (GHG) emissions of the building sector, anthropogenic GHG emissions are a primary cause of global warming and rapid climate change. The carbon footprint of today’s building stock includes the following key statistics: 76% of building energy comes from fossil fuels, 72% of all electricity is consumed by the building sector, and 47% of GHGs are produced by the building sector.
A related consideration is the difference between the new construction and renovation markets. New construction makes up only 2 percent of construction activity and 12 percent of all construction spending.
“In spite of a continued focus on new buildings,” Patterson said, “a review of these conditions make it clear that renovation of the existing building stock is the fastest and most effective way to improve the performance of the building sector.
The commercial building stock is comprised of approximately 5 million buildings representing many different building types. In addition, most of these are custom designed to variables of use, location and other considerations. Thus, one of the challenges presented by the building sector is the wide diversity of buildings requiring refurbishment. Renovation strategies will need to be finely tuned to each building type and design. Tall curtainwall buildings are a unique building type, and the particular focus of Patterson’s research.
“Today’s curtainwall industry was born in the mid twentieth century’s post-war building boom, amidst a convergence of demand for new office building space and the emergent technology of lightweight cladding systems,” Patterson said. “The resulting construction activity redefined the skylines of the major urban areas of Europe and North America.”
Advances in material science and new technology had set the stage for the rapid deployment of new high-rise buildings. Structural systems, elevator technology, air conditioning, architectural glass and aluminum were all readily available to an expanding marketplace. The real estate community recognized new thin building skins as a means to gain significantly more leasable floor area out of the same building footprint. These conditions spawned the rise of the glass curtainwall skyscraper as a dominant urban building type, the propagation of which continues to this day (although the region for new construction of tall buildings has undergone a dramatic shift from Europe and North America to Asia). The aging of this building type is presenting a concerning infrastructure challenge.
“Many of these early tall buildings are approaching 40 years of age or more,” Patterson said. “In addition, the early curtainwall technology was less robust — the facade industry was new and lacking in experienced designers, fabricators, and installers, and these early tall buildings were often poor performers to begin with. They were typically single-glazed because insulated glass was expensive and energy was cheap. The lack of thermal breaks has comprised energy efficiency and comfort. Poor design detailing and craftsmanship has resulted in a history of air and water infiltration.”
Patterson has examined and categorized basic strategies for the facade retrofit of tall curtainwall buildings. In the process of examining existing retrofit practices in relation to various green construction standards, Patterson has identified certain conditions that compromise the sustainability of these practices, but many of these trace back to problems caused by the facade practices for the original building — practices which remain characteristic of the current facade design of new buildings.
“Curtainwall systems are not designed with any consideration given to their inevitable retrofit”, Patterson said, “severely limiting the options when the need arises. Often the entire facade system is needlessly stripped off and replaced with a new one because simply changing out the glass infill panels is too difficult.”
This prevents the optimal reuse of the existing system’s components and assemblies, a sustainable design objective. The need for the retrofit of these building facades is readily identifiable, claims Patterson, and he proposes that consideration of this eventuality should be accommodated in new building facade design.
Patterson’s presentation examined a number of recent facade retrofits as case studies, including the Jacob K. Javits Convention Center’s complete facade replacement, the renovation of the Empire State Building, the over-cladding retrofit of 3 Columbus Circle, and the renovation of the Rodino Federal Building, which included the addition of a new glass skin outboard of the existing facade.
Day two and three of the World Congress concluded with presentations from other leading building owners, developers, architects, engineers, contractors, and urban planners. Enclos is proud to be a member of the Council on Tall Building and Urban Habitat and fully embraces it’s commitment to the built environment. Patterson expressed enthusiasm for other programs at the Shanghai Congress, each addressing the various aspects of the building skin. He has been asked by the CTBUH to prepare a brief report on these programs, and the report will be available through the CTBUH.
Patterson’s complete paper, along with approximately 100 others that comprised the Congress program, is available in a bound volume of proceedings available through the CTBUH here. Additional information on the CTBUH’s 9th World Congress is available here.
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