From Historic to Cutting Edge: Revitalizing Iconic Buildings

Fenway Park, the Eiffel Tower, Empire State, and other storied structures were upgraded for 21st-century energy efficiency.

The world’s iconic buildings achieve celebrated status because their architecture stands the test of time. But what lies beneath those enduring facades?

Design and engineering evolve quickly, and many urban buildings—nearly half the office space in New York City was built before 1945—predate concepts like sustainability, climate change, and even recycling, resulting in waste and inefficiency.

Enter the retrofit. Aging buildings are updated with new windows, lighting, plumbing fixtures, and heating and cooling systems, ultimately saving owners and operators money while they conserve energy.

Buildings consume 73 percent of the electricity in the U.S., and indirectly create 38 percent of carbon dioxide emissions—more than industry or transportation. To win the battle against climate change, cities will need to run on more efficient buildings. (See what makes a “green building.”)

These historic icons blazed a trail for other buildings to follow.

Empire State Building

The Empire State Building grabbed New York’s attention when it unveiled dazzling new LED lights in 2012. Not only did the color options increase from nine to a kaleidoscope of millions, it used a quarter of the electricity of its original floodlights. While the evening light show turned heads, a more subtle transformation was under way—an overhaul that would prove even old skyscrapers can get a new lease on life. (See New York’s rapidly evolving skyline.)

The owners of the building needed to address a persistent complaint from its 30,000 office tenant workers: In summer the interior of the Depression-era structure could get too hot for the air-conditioning system to adequately cool. The conventional solution called for more powerful chillers (basically, giant air-conditioning units), a cost of over $17 million. Instead, management decided to invest in improvements that would reduce energy use—and hopefully boost the bottom line in the process.

After a team of experts analyzed the building, over 60 ideas were whittled down with computer modeling to eight—the most worthwhile and practical were chosen. Upgrades ranged from heating and cooling components to lights that automatically dim during the day to simple barriers that prevent heat from radiators escaping through the walls.

The building’s 6,500 double-pane windows proved to be particularly wasteful. But instead of replacing them, they were removed, refurbished on-site, and reinstalled—after-hours, to avoid disruption. A gas-filled film, which acts as an insulating third pane, was added, and now the “superwindows” reduce summer heat gain and winter loss by more than half.

<p>Chicago is one of several U.S. cities promoting the use of green roofs. It put plants atop its own iconic Chicago City Hall, bringing color to its roof and lowering its summer temperature.</p>

Chicago is one of several U.S. cities promoting the use of green roofs. It put plants atop its own iconic Chicago City Hall, bringing color to its roof and lowering its summer temperature.

Photograph by Diane Cook and Len Jenshel, Nat Geo Image Collection

The $13 million energy-efficiency retrofit was completed in 2013, and the upgrades cut energy consumption by almost 40 percent, saving over $4 million annually. It is expected to eliminate 105,000 metric tons of CO2 emissions over 15 years.

“We hoped people would recognize the compelling financial case behind whole-building retrofits,” says Cara Carmichael of the Rocky Mountain Institute, an organization that partnered on the project. “This model has served as a huge catalyst in the industry.” (Watch a video on the retrofit.)

Fenway Park

The trademark of Boston's Fenway Park is the Green Monster wall that towers over left field. On Opening Day in 2015, Fenway—major league baseball’s oldest stadium—introduced fans to an unexpected feature that’s a different kind of green: a 5,000-square-foot rooftop farm. (Read about the benefits of a green roof.)

The area once did little more than cover the Red Sox executive offices, but last year Fenway Farms—as the agriculture project is known—grew nearly 6,000 pounds of organic food for the park in its rows of irrigated, repurposed milk-crate planters. Collaborating with park chefs, the farm provides some of the produce used at Fenway’s fine-dining restaurant (a farm-to-table trip of just 300 feet) as well as at concessions. Though not yet a ballpark tradition, even a trendy kale wrap made its way into the offerings, alongside hot dogs and fries.

The farm is part of a larger sustainability effort the Red Sox launched in 2007, in partnership with the Natural Resources Defense Council. A year later, Fenway became the first major league ballpark to install solar panels, an investment that reduced reliance on natural gas, used to heat water, by 37 percent. Another program, called the Green Team, sends volunteers into the stands between innings to collect recyclables, which saves almost 400 tons of waste from landfills.

For the Red Sox, Fenway Farms is a home run. “When you grow up in a city you’re so far removed from traditional farming,” says Jessie Banhazl, CEO of Green City Growers, which runs the farm and targets unused urban space. But it’s been elevated, she says, by simply being a part of the ballpark. “It educates people as to how food grows, that we all could be growing fresh vegetables at home, either on your balcony or in your backyard.”

Fenway’s example has expanded into a larger movement. Today the Green Sports Alliance helps pro and college teams incorporate more sustainable practices, counting 16 different leagues and 193 teams as members, including every major league ball club.

Eiffel Tower

On the night the Paris Agreement on climate change went into effect last year, the lights that illuminate the Eiffel Tower—some of the most famous in the City of Lights—were turned green to honor the occasion. But the monument is doing more than raise awareness. In keeping with its original raison d'être as a symbol of engineering know-how, the tower was upgraded as part of a four-year, $37 million renovation, completed in 2015.

On the first level, at a height of 187 feet, three pavilions housing a restaurant, conference room, and shop were rebuilt or refurbished. More than 100 square feet of solar panels were mounted on the pavilion roofs, creating enough power for half the hot water used at that level. New rain collectors funnel water to toilets, saving water and cutting the workload of pumps. LED lighting throughout lowered electricity use, and enhanced glazing on the glass partitions reduced solar heat gain by 25 percent, along with air-conditioning needs during the summer.

On top of saving energy, the tower now makes some of its own: Hidden between the wrought iron lattice above the second floor’s restaurant, two 17-foot turbines make power from winds. The 400-foot elevation catches the best breeze, and the windmills’ vertical axes spin regardless of wind direction. The turbines generate 10,000 kilowatt hours per year—nowhere close to the tower’s overall electricity needs, but enough to power the energy-efficient first floor.

Sydney Opera House

The soaring sails of the Sydney Opera House are a masterpiece of organic design, inspired by wings, palm trees, and shells—and the landmark borrows more from nature than just form. Since its inaugural performance in 1973, the building’s air-conditioning system has been cooled by seawater drawn from the surrounding harbor, a pioneering solution that reduces freshwater use.

Over the past decade management has expanded that spirit of sustainability to other features of the building and even to its events. Replacing the lights with LEDs cut the concert hall’s electricity consumption by 75 percent, which lowered the annual power bill by over (U.S.) $50,000.

Management also slashed the waste produced by staff and the eight million people who visit the venue and its restaurants each year. The types of materials recycled grew from two to eight, which boosted the overall recycling rate from 20 percent to 65 percent—and hopes to reach 85 percent. Food waste is targeted too. Some is sent to a bioenergy fuel producer; edible surplus is donated to a local charity.

Not all solutions are necessarily high tech. To extend the life of building materials, the cleaning crew traded corrosive chemical cleansers for natural ones, which has also lead to better indoor air quality. Baking soda is used to wash concrete walls while olive oil and a dash of alcohol burnish the bronze.

“The Sydney Opera House is very much on the world stage, so the things we do here can inspire others,” says sustainability manager Emma Bombonato. “That’s a really important responsibility. We’re trying to set a great example.”


After the Berlin Wall fell and Germany reunified in 1990, the government made massive investments in the former communist east. One modernization project was particularly crucial to the new Germany—the restoration of the Reichstag, the former and future seat of the federal parliament. When the renovation was completed in 1999, the 19th-century building was more than a home for the legislature, it stood as a symbol of a brighter future.

The most prominent element of lead architect Norman Foster’s design is the innovative glass dome, widely regarded as a masterpiece of form and function. A cone of mirrors reflects natural light down into the chamber below, minimizing the need for artificial lighting. An automated shade—powered by solar panels on the roof—circles the cone to block direct sunlight, eliminating glare and reducing heat gain. The dome also works as an exhaust, venting hot air through the top without fans. At night, artificial light from the legislature below reflects outward, “a beacon,” Foster said, “signaling the vigor of the German democratic process.”

The Reichstag’s power and air-conditioning systems are equally innovative and ecofriendly. An on-site generator powered by biofuel supplies 80 percent of the building’s electricity and 90 percent of the heat. The system’s efficiency is boosted by a geothermal heat pump that sheds excess heat or cold through a circuit of underground pipes. As a result, carbon emissions plummeted by 94 percent.

Buildings are crucial to Germany’s ambitious energy goals. Current policy targets a 50 percent reduction in energy use by mid-century; buildings are slated to slash energy demand by 80 percent at that time, through accelerated renovations and the use of on-site renewables.

Transamerica Pyramid

The Transamerica Pyramid’s angled silhouette has defined the San Francisco skyline since it arrived in 1972—the city’s tallest building until last year. That shape does more than just stand out: the wide, heavily reinforced base helps the building withstand earthquakes.

Unlike a traditional black, flat roof topping many structures, the innovative design also resulted in a rather green building for the era. The reflective white quartz aggregate exterior and the triangular top absorb less heat from the sun, which reduces the energy required to cool the building—serendipitous benefits.

In the 2000s the building owners began a series of overhauls, spurred in part by San Francisco’s green building requirements. “Lighting is low-hanging fruit,” says Barry Giles, a sustainable-building expert who guided the retrofit, about the switch to LEDs. “But there’s a knock-on effect—LEDs don’t produce heat.” Other easy upgrades included lights and air-conditioning that only activate when people are present.

Encouraged by results, management doubled down on their investment by installing a $4 million gas-fueled cogeneration plant in the ground-floor garage. The hyperefficient system, which is based on a jet engine, generates 70 percent of the building’s electricity, while a process byproduct meets the building's heating needs. The system reduced electricity consumption, saving $700,000 a year. In 2011 the Transamerica Pyramid was certified LEED Platinum, the country’s highest rating for green buildings.

Giles estimates that about ten percent of 5.6 million commercial buildings in the U.S. have become “high performance," thanks to upgrades. “The difficulty now comes in trying to replicate that in the other 90 percent,” says Giles, CEO of BREEAM USA. “We’ve got to come up with new ways to show how easily they can make changes that can improve their bottom line, but also save energy and carbon emissions.”

This article is part of our sponsored Urban Expeditions series.

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