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RMI Retrofits America's Favorite Skyscraper

The Empire State Building, a new model for energy efficiency
By Molly Miller

When you gaze out over the vast canyons of Manhattan from the 86th floor observatory deck of the Empire State Building (ESB), you are looking at one of the greenest cities in the United States. New York City's per capita emissions are a third of those in the rest of country because of public transit use, density and smaller residences. New York also vows to reduce current carbon emissions by 30 percent by 2030.

And, if the Empire State Building— constructed during the great depression in just over a year, then the highest building in the world—embodies the ambition of New York, then it only makes sense for it to be evolving toward green now, too. Such was the visionary thinking over the last year when the owners of the building took a planned capital improvement renovation to another level by asking Rocky Mountain Institute and a team of experts to recommend sustainability measures that could be incorporated into the planned renovations.

"My wife and I have a very deep commitment to sustainability. It’s our belief that sustainable practices in everything are critical to our future," says Tony Malkin, who owns the Empire State Building.

Malkin's renovations will provide state-of-the-art office building amenities in a historic building, and with RMI's recommendations, the renovations have the potential to greatly reduce both energy use and carbon emissions. While typical retrofits aim to reduce energy consumption by 10–20 percent, RMI proposed an integrated approach that includes whole-building considerations to realize savings of almost 40 percent.

To date, few, if any examples of great pre-war multi-tenant building retrofits that achieve these standards exist and the ESB project provides a practical model for other existing building owners to replicate. Setting this precedent is especially important now as nearly 75% of the U.S. commercial building stock is 20 years or older.

“Historically, improvements in existing buildings are made on an ad hoc basis," says Kathy Baczko, NYC City Director of the Clinton Climate Initiative. "However, so much more energy efficiency and savings can be obtained by taking a whole building approach, when integrated solutions and blended savings bring long term benefits. More owners and operators should take advantage of them as the Empire State Building is doing today.”

"The idea that the Empire State Building would undergo a green retrofit is immensely inspiring to building owners across the boards, whether it’s in New York or in any other city, because the Empire State has always been the signature building of New York," adds Carol Willis, founder, director, and curator of the Skyscraper Museum.

The 102-story Art Deco skyscraper at the intersection of Fifth Avenue and West 34th Street has been named by the American Society of Civil Engineers as one of the Seven Wonders of the Modern World, according to the ESB website. The building and its street floor interior are designated landmarks of the New York City Landmarks Preservation Commission and it was designated as a National Historic Landmark in 1986.

"This building is a great example of the right kind of building to retrofit," Fluhrer says. "The fact that it is an iconic building that is going to be around for a long time to come means it makes sense to invest in it. And the fact that it could be coordinated with a major capital improvement project made it really cost effective and the owners can save a lot of carbon. "

The capital improvement plan, for example, called for resealing all the windows so they open and close properly. "If you are going to be disturbing tenants and moving them around anyway to work on windows, you might as well put in new energy efficient windows," explains Fluhrer.

Wendy Fok, an architect with Jones Lang LaSalle, who worked with RMI and the rest of the team on the ESB recommendations, explains the process for retrofitting the Empire State Building's 6,514 operable windows for energy efficiency: "We use the frames, remove the sashes, reuse the glass, clean it. But between the glass, you’ll have an intermediate material which is actually a low emissivity (low-E) film, so even though they call it a triple glazed window, it’s actually reusing the existing glazing and inserting a (low-E) film between the two pieces."

The air handling units provide another example of how RMI's recommendations capitalized on the pre-existing capital improvement plan. RMI recommended that instead of replacing old units with the same type of unit, as was the practice, ESB should replace them with a higher quality floor mounted unit when they wear out. While the cost would be marginally higher, the efficiency would be much greater and ESB would only need two units per floor instead of the four units per floor they have had in the past.

The ESB Retrofit Team

RMI partners on the project included Clanton & Associates (lighting engineers), Rumsey Engineers (mechanical engineers), and Alpen Energy Group (glazing experts). Johnson Controls, Inc. (JCI) was selected as the preferred Energy Service Company (ESCO) while Jones Lang LaSalle (JLL) was selected as the project manager. The RMI team provided engineering consulting services, including peer reviews of the development of JCI’s package of facility improvement measures, and supported the project documentation and outreach process.

"It really was a collaboration," says Fluhrer. "We work with others all the time, but we truly worked as a team. It was challenging but instilled a lot more confidence for the owner. When three world-renowned groups come to the same conclusion, it makes it easier to move forward."

To achieve these results, ESB would need to implement eight key projects or measures. The recommended package of measures also reduces cooling load requirements by 33% (1600 tons). The measures would reduce peak electrical demand by 3.5 MW, benefitting both the building and the utility. This package of measures also results in enhanced indoor environmental quality for tenants, by way of better thermal comfort resulting from better windows, radiative barriers, and better controls; improved indoor air quality resulting from tenant demand controlled ventilation; and better lighting conditions that coordinate ambient and task lighting.

The recommended package of measures includes projects related to:

  • Direct Digital Controls (DDC),
  • Tenant Lighting, Daylighting, and Plugs,
  • Variable Air Volume (VAV) Air Handling Units (AHUs),
  • Retrofit Chiller Plant,
  • Building Windows,
  • Tenant Energy Management Program,
  • Radiative Barrier, and
  • Tenant Demand Control Ventilation (DCV).

Tenant Design

The team has identified three key programs to influence tenant energy use –-the tenant pre-built program, tenant design guidelines and a tenant energy management program. Nearly 40% of tenant space will turnover in the next fours years, so aggressive guidelines are needed immediately. RMI's proposed green pre-built design will save $0.70 - $0.90/sf in operating costs annually for an additional cost of $6/sf and help ESB demonstrate design principles for all tenants to endorse. Design guidelines, based on this pre-built program, will provide green ESB standards. Tenants can verify the technical and economic validity of the recommendations by accessing the tenant financial tool RMI created specifically for ESB. For the tenant energy management program, ESB will begin sub-metering all tenant spaces and manage a feedback/reporting system to inform tenants about their energy use. This program will also assist tenants with their own carbon reporting efforts.

Tenant Pre-Built Space

The ESB team designed a new pre-built space on the 42nd floor (currently in construction) for the Empire State Building to market to prospective tenants. Key design features include a low-pressure drop HVAC system design, an indirect layered lighting system design (ambient-task-accent lighting), new high-performance glazing, light shelves, and blinds, and high-recycled content and local, and healthy construction materials.

Next Steps

The ESB team is in the process of evaluating all the recommendations for increasing energy efficiency and lowering carbon emissions to determine which measures will be incorporated into the renovations. Regardless of the measures adopted, RMI hopes other building owners can use the analysis and recommendations to replicate the process of existing building retrofits. RMI's next steps include securing funding to report out lessons learned from the ESB retrofit analysis.

"There is further work to be done to capture the lessons learned, systematize the process and disseminate the results to broad audience, says RMI Vice President Stephen Doig, who consulted on the project. According to Doig, some of the lessons from the project include:

"Carrying out retrofits in sync with the normal upgrades to the building makes many more options economically possible. Second, there is a natural tension between maximizing investment returns and maximizing CO2 reduction. It is important to acknowledge that this tension exists and consider funding mechanisms that provide incentives to achieve the maximum efficiency improvement in an economically viable manner. The work also made clear that delivering real reductions needs to engage and incent owners, ESCOs, tenants and building managers. We were fortunate in our project that was the case and it needs to become the norm in the future. Finally, we learned that we need to make our approach replicable so it can be widely adopted. "

"From the larger dissemination point of view, I think the most exciting thing is the fact that the Clinton Climate Initiative brings us this platform of the 40 large cities of the world with a pretty substantive existing building stock comprised largely of commercial office buildings," says Aalok Deshmukh, who worked as RMI's project manager on the ESB recommendations. Working on the Empire State Building to create an exemplary building retrofit project for the rest of the world to replicate, came about in large part due, to RMI's collaborative work with the Clinton Climate Initiative on their Energy Efficiency Building Retrofit Program, carried out in New York City, in 2007.

"All portfolio managers and real estate owners to some extent have been concerned with energy-efficiency, and they’ve done small things. What this project is going to show is that it actually makes sense to make large and significant energy-efficiency improvements, not the five to 10 percent type things, but the 20 to 30 percent and more type of improvements, and that there is a business case for doing so, " says Clay Nesler, VP, Global Energy and Sustainability, at Johnson Controls.

The Empire State Building retrofit provides a glimpse of what is possible for the future of our existing buildings and the future of our cities. As Carol Willis puts it, "The Empire State Building is the best place to go in order to see the city of New York and the lay of the land as you, as you look out towards the continent or towards the ocean…The Empire State Building stands in this kind of exceptionalism that hopefully will never be compromised."

Key Findings and Recommendations

The project kicked off on April 14th 2008. Collaborative team activities took place over a six-month period between April and November of 2008. At the conclusion of the seven-month project development process, the team found that at current energy costs, ESB could cost-effectively reduce energy use by 38% and save 105,000 metric tons of CO2 over the next 15 years. Achieving an energy reduction greater than 38% appears to be cost-prohibitive, given current conditions.

Energy Model & Financial Tool

RMI helped make the financial case for the energy retrofit measures by providing the retrofit team with tools to measure and capture financial and energy analysis. Because of the formal documented analysis through the tools the project has an unusual transparency. This transparency allows anyone to test the results and to replicate them in other circumstances and other projects.

In close collaboration with RMI, JCI ran energy analyses using DOE-2.2 (eQUEST interface), a building energy simulation tool that allows for the comparative analysis of building designs and technologies. By inputting weather files, building geometry, material properties, equipment schedules, and system components, the program computes building loads and outputs building energy use.

Once preliminary energy savings estimates for individual measures were provided, the team turned to the financial model (developed by RMI specifically for this project) to determine how to create packages of measures that maximized greenhouse gas savings while providing reasonable economic benefits.

Iterations between these models helped the ESB team make final recommendations to ESB ownership regarding specific short-term and long-term projects and programs they can implement.

Clinton Climate Initiative

In 2006, the Clinton Foundation launched the Clinton Climate Initiative (CCI), an initiative aimed at reducing global greenhouse gas emissions. The initiative targets the world’s largest cities, which are responsible for 75 percent of all global greenhouse gas emissions.

The first program within CCI, the Energy Efficiency Building Retrofit Program (EEBRP), addresses greenhouse gas emissions generated by existing buildings. Within large urban areas, buildings are huge energy consumers, responsible for approximately 70 percent of a city’s carbon footprint. In New York City, buildings are responsible for 79 percent of all greenhouse gas emissions.

EEBRP brings together banks, product suppliers, energy service companies, and public and private building owners to drastically reduce energy consumption in existing buildings, including the Empire state Building.

"In large cities around the globe, buildings typically produce the most carbon emissions, most atmospheric pollution; it’s often the 70 to 80 percent of the total energy used in a city goes into the operation of buildings. So if we can retrofit existing buildings in cities, it could have a major impact on carbon emissions," says RMI's Greg Franta.

CCI has a relationship with RMI to assist CCI in guiding and encouraging integrated approaches to energy efficiency improvements—an approach that can achieve much deeper energy savings—rather than more conventional one-off lighting or HVAC upgrades that leave deeper savings permanently unavailable.

Building the Empire State Building

  • Construction began on March 17, 1930. It took one year and 45 days to build.
  • William Lamb, an architect at the firm Shreve, Lamb & Harmon, was chosen to design the Empire State Building. He happened to base most of his design on a simple pencil. The clean, soaring lines inspired him, and he modeled the building after it.
  • In 1945 at the end of World War II, an Army Air Corps B-25 twin-engine bomber plane crashed into the 79th floor of the building in dense fog.
  • From 1931 to present, the building has acted as an "Ambassador to New York" to many of the world's renowned political and entertainment figures, such as, Fidel Castro, Queen Elizabeth, Prince Charles, Prince Andrew, The Duchess of York, Nikita Khrushchev, King of Siam and others.
  • The building's dirigible mast (now the base of the TV tower) was originally designed as a mooring mast for Air blimps (unfortunately because of several unsuccessful attempts and the volatile wind conditions at 1,350 feet, the idea was ultimately abandoned).

Molly Miller is a communications specialist at RMI

--Published April 2009