Study Reinforces Carbon Benefit of Renovation
When the United Nations planned the multi-year, campus-wide renovation of its New York City headquarters, it made sustainability a priority. The resulting project, completed in 2015, was designed and built to meet the equivalent of a LEED Gold rating and the iconic Secretariat Building to meet the equivalent of a LEED Platinum rating. But according to a new analysis, the greatest impact on sustainability stems from the decision to retrofit the existing buildings rather than demolish and replace them.
The U.N. study quantifies the benefits of this decision by assessing the carbon cost––both embodied and operational—of renovation compared with demolition and new construction.
The study (led by Michael Adlerstein, assistant secretary-general and executive director for the U.N. Capital Master Plan, and prepared by Vidaris, Inc. and Syska Hennessy Group) confirms that the retention of the structural components, opaque envelope, and core walls of the U.N. complex’s existing buildings has resulted in significant carbon savings—both in terms of embodied energy and carbon emissions. The savings are substantial enough to not be easily offset by the more energy-efficient building operations of new construction.
The study was based on life-cycle analysis calculations and energy modeling. It found that, had the existing buildings been demolished and replaced with new construction, it would have taken 35–70 years to offset the associated carbon cost with the improved operating efficiency of new buildings.
The findings of this study gain further significance considering the critical timeframe that climate change confronts us with. As noted in the report, climate scientists believe there is a small window for stabilizing and reducing greenhouse gas emissions. This means that the extra energy and carbon required to replace existing buildings with new construction is counter-productive, especially when we consider the rate at which carbon is purged or reabsorbed from the earth’s atmosphere. (Scientists estimate carbon’s atmospheric life to be between 100 and 300 years—which means that the carbon burden of the original U.N. construction is still in the atmosphere.)
For more on the topic of the value of existing buildings and carbon, read:
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Published May 25, 2017