Project Case Study: Empire State Building

This case study by the Rocky Mountain Institute (RMI) details a deep energy efficiency retrofit of the Empire State Building in New York City. The project focused on reducing thermal loads and upgrading systems to achieve significant energy savings and carbon reductions, utilizing an integrative design process and life cycle cost analysis to balance financial returns with environmental goals.

• The energy retrofit of the Empire State Building is projected to reduce annual energy use from 88 kBtu/sf to 60 kBtu/square foot, representing an expected 38 percent energy savings.
• The project achieved a total cost of $550 million for the entire remodel, with $106 million specifically allocated to energy-related projects and an incremental capital cost of $13.2 million. Annual energy cost savings are projected at $4.4 million, resulting in an overall incremental simple payback of three years.
• A critical strategy involved 'tunneling through the cost barrier' by first reducing the building's cooling demand, which allowed the existing chiller plant to be renovated rather than replaced. This reduced the required cooling capacity by 1,600 tons and saved $17.3 million in budgeted capital expenditure.
• The most innovative measure was the onsite remanufacturing of 6,514 windows into 'superwindows' using a suspended coated film and gas fill. This project cost $4.5 million and is projected to save $410,000 annually by tripling the insulating value of each window and cutting winter heat loss by at least two-thirds and summer heat gain by half.
• The project team used a tiered approach to identify opportunities: first reducing loads (via window retrofits, radiant barriers, and lighting), then installing efficient systems (chiller and VAV air handling unit retrofits), and finally implementing ongoing monitoring (tenant energy management, demand control ventilation, and direct digital controls).
• To balance financial constraints with carbon goals, the team developed four different bundles of measures: 'NPV Max', 'Max CO2', 'NPV Neutral', and 'NPV Mid'. Building ownership ultimately selected the 'NPV Mid' package.
• Tenant engagement was managed through three programs: a tenant pre-built program (offering spaces that save $0.70–0.90 per square foot in annual operating costs), tenant design guidelines, and a tenant energy management program featuring sub-metering and real-time feedback dashboards.
• The building achieved an Energy Star score of 90 out of 100, placing it in the top 10 percent of all buildings for energy efficiency, and is on track to receive LEED for Existing Buildings: Operations & Maintenance.

APA

Harrington, E., & Carmichael, C. (2009). Project Case Study: Empire State Building. RMI. https://rmi.org/app/uploads/2017/04/Buildings_Retrofit_EmpireStateBuilding_CaseStudy_2009.pdf

Chicago

Harrington, Eric, and Cara Carmichael. Project Case Study: Empire State Building. RMI, 2009. https://rmi.org/app/uploads/2017/04/Buildings_Retrofit_EmpireStateBuilding_CaseStudy_2009.pdf.

Wikipedia

{{cite report |last1=Harrington |first1=Eric |last2=Carmichael |first2=Cara |title=Project Case Study: Empire State Building |publisher=RMI |date=2009 |url=https://rmi.org/app/uploads/2017/04/Buildings_Retrofit_EmpireStateBuilding_CaseStudy_2009.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{harrington2009project, author = {Harrington, Eric and Carmichael, Cara}, title = {{Project Case Study: Empire State Building}}, institution = {RMI}, year = {2009}, url = {https://rmi.org/app/uploads/2017/04/Buildings_Retrofit_EmpireStateBuilding_CaseStudy_2009.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }