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Buildings and Cities


A receptionist sits behind the information booth during the $530 million retrofitting of the Empire State Building, originally constructed in 1931. The retrofit to the Art Deco icon saw the replacement of all 6,500 windows and all heating, cooling, and lighting systems—an energy reduction of 38 percent.

Worldwide, buildings account for 32 percent of energy use and 19 percent of energy-related greenhouse emissions. They pull from the electric grid or natural gas lines to heat, cool, and light the spaces within them and to power appliances and machinery. As much as 80 percent of the energy consumed is wasted—lights and electronics are left on unnecessarily and gaps in the building’s envelope allow air to seep in and out, for example.

Much of the attention paid to green buildings is in new construction, but retrofitting brings energy efficiency to the existing built environment. The world has 1.6 trillion square feet of building stock, 99 percent of which is not green. Retrofitting addresses how heat and cold are escaping or entering the building, the systems that cool or warm inhabitants, and how spaces are illuminated. It ultimately improves the experience of being inside the building.

Retrofitting is a well-understood practice, and good building performance data is making it increasingly effective. The payback on retrofits, depending on the building, is five to seven years on average. A recent retrofit of New York’s iconic Empire State Building will cut energy use by 40 percent and avert 105,000 tons of greenhouse gas emissions.


“world’s tallest building”: Tauranac, John. The Empire State Building: The Making of a Landmark. Ithaca and London: Cornell University Press, 2014.

buildings…energy use and…emissions: Lucon, O., D. Ürge-Vorsatz, A. Zain Ahmed, H. Akbari, P. Bertoldi, L. F. Cabeza, N. Eyre et al. “Buildings.” In Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge, UK, and New York: Cambridge University Press, 2015.

[U.S.] buildings’ energy consumption: U.S. Department of Energy. “Buildings Share of U.S. Primary Energy Consumption (Percent).” Buildings Energy Data Book.

80 percent of…energy…wasted: Next 10. Untapped Potential of Commercial Buildings—Energy Use and Emissions. San Francisco: Next 10, 2010.

critical to modify existing buildings: Al-Kodmany, Kheir. “Green Retrofitting Skyscrapers: A Review.” Buildings 4, no. 4 (2014): 683-710; Preservation Green Lab. The Greenest building: Quantifying the Environmental Value of Building Reuse. Washington, D.C.: National Trust for Historic Preservation, 2011.

buildings in the United States; commercial: Nemtzow, David. “140 Million Places to Save Energy.” September 1, 2016; U.S. Energy Information Administration (EIA). 2012 Commercial Buildings Energy Consumption Survey.

[longevity] of the existing building stock: Ma, Zhenjun, Paul Cooper, Daniel Daly, and Laia Ledo. “Existing Building Retrofits: Methodology and State-of-the-Art.” Energy and Buildings 55 (2012): 889-902; Campbell, Iain, and Koben Calhoun. “Old Buildings Are U.S. Cities’ Biggest Sustainability Challenge.” Harvard Business Review. January 21, 2016.

Empire State Building…energy [use]: Malkin, Anthony E. “Four Reasons Why the Empire State Building Retrofit Model Works.” The Clinton Foundation. August 12, 2014.

retrofit…[reduce] usage by 40 percent: Harrington, Eric and Cara Carmichael. Project Case Study: Empire State Building. Rocky Mountain Institute, 2009.

energy costs and…emissions [avoided]: Navaro, Mireya. “Empire State Building Plans Environmental Retrofit.” New York Times. April 6, 2009.

windows…rebuilt on-site: Lehner, Peter. “Empire State Building Cuts Energy Waste, Becomes Unexpected Model of Efficiency.” Natural Resources Defense Council. October 26, 2012.

buildings over 500,000 square feet: EIA, Commercial Buildings.

commercial buildings…[rate] upgraded: Olgyay, Victor, and Cherlyn Seruto. “Whole-Building Retrofits: A Gateway to Climate Stabilization.” ASHRAE Transactions 116, no. 2 (2010).

[returns on] retrofitting [U.S.] buildings: Fulton, Mark, ed. United States Building Energy Efficiency Retrofits: Market Sizing and Financing Models. New York: The Rockefeller Foundation and Deutsche Bank Climate Change Advisors, 2012.

1.6 trillion square feet of building stock: Navigant Research. Global Building Stock Database. Boulder: Navigant Research, 2015.

Rocky Mountain Institute…strategy in Chicago: Campbell and Calhoun, “Old Buildings.”

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