New York's Environmentally Responsible Skyscrapers

by ‐ Tags: alternative energy, building science

As flagship buildings, skyscrapers are powerful symbols of what we value as a country. Throughout the past century, prominent buildings from the Chrysler to the Sears have helped tell the story of our nation through architecture.  Looking forward, the 21st century is no different, and when it comes to the environmental impact of buildings, looking to notable buildings can help frame the important issues at play.  

There are two primary ways to reduce the impact of our building stock - new construction and retrofitting the current building stock.  In this post, we’ll take a look at two iconic buildings that represent strides in both directions. 

Taking a glance at recent development in New York City, we can compare the new 1-WTC, currently being built on the site of the World Trade Center, to the recent renovation of the venerable Empire State Building.


Once called the Freedom Tower, the newly re-dubbed 1-WTC is expected to be completed by late
2013 and is poised to be one of New York City’s most environmentally sustainable buildings.   The development group behind the new flagship of the WTC plaza aims to have 1-WTC earn LEED-Gold Certification, joining it’s neighbor, 7 World Trade Center (complete), which has already achieved LEED status.

Highly efficient building and mechanical systems are designed to incorporate daylighting and occupant behavior, and will exceed NYC code by 20%

At the base of the tower, one of the largest fuel-cell installations in the world will provide about 30% of the building’s anticipated electrical needs.  The new installation will help 1-WTC draw less water from the nearby Hudson River than it’s predecessor, and will supply energy without combustion, reducing the building’s total emissions. Excess heat produced by the fuel-cell plant will be used to offset some of the heating needs for the lower portions of the building. 

The Empire State Building

Perhaps the most iconic skyscraper in America, the Empire State building underwent a major renovation in 2012 to update it’s building envelope, mechanical systems, and operations, reducing the building’s energy consumption by 38%.

The retrofits, which exceeded initial expectations for energy reduction, began with an overhall of the building’s windows, which were cleaned and upgraded, with the addition of a film/gas layer, reducing heat loss dramatically.  The window improvements allowed the team to replace the chiller units with smaller, more efficient equipment, further reducing energy demand. 

The retrofit team also incorporated sophisticated control measures such as controllable lighting and ventilation systems, putting control of comfort and environmental quality in the hands of the building’s tenants. All told, the retrofits reduced peak electrical demand by 3.5 megawatts, and cooling load by 33%.  

Designing Holistically

Both 1-WTC and the ESB retrofit are projects that are designed to take into account the whole-building, including surrounding areas, unexpected tenant usage, and occupant behavior & comfort. 

More than just a tower, 1-WTC is being designed and built as a part of the newly constructed World Trade Center Plaza, in conjunction with three other towers, a new transit hub, public park, and the 9/11 memorial and museum.  The developers of the plaza are using integrated design practices and taking advantage of holistic building methods.  For example, the cooling equipment in the base of 1-WTC will serve as a centralized cooling plant for the new transit station, the museum, and the memorial.  By combining building systems, the system is able to serve multiple structures with less energy.

How the ESB management is incorporating tenants in the retrofit process is a major part of the Empire State Building's renewal. As tenant-occupied leases turn over in the coming years, the ESB's management team will offer tenant-space design services, as well as energy-tracking tools to submetered spaces.  By giving tenants the option to reduce their utility costs and contribute to the ESB's sustainability goals, the building's ownership aims to solve the split-incentive problem, and reduce energy costs building-wide

Two Paths to Sustainability

It is clear that building new, energy-efficient buildings is not enough to control our energy use and reduce utility costs.  Moving forward, our cities will need examples of smart, resource-efficient design in both new construction and in old classics.


Keep Reading:

Interested in learning more about these projects? Click through the links below:

RMI Retrofits America's Favorite Skyscraper

Whole-Building Design Guide's Profile of the Empire State's Retrofit

Alliance to Save Energy's profile of the new WTC