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Empire State Building: Monumental Energy Retrofit

The Empire State Building plans to trim 38 percent from its monumental $11 million annual energy bill with an energy efficiency retrofit. Clay Nesler of Johnson Controls joins Denis Du Bois for an interview about the project.

This is a highlight from the Building Priorities Briefing.

Empire State Building photo on EnergyPriorities.com courtesy City of New York

The Empire State Building plans to trim 38 percent from its monumental 11 million dollar annual energy bill with an energy efficiency retrofit. (City of New York photo)


Denis Du Bois: Possibly the most talked-about case study at Greenbuild 2009 was the Empire State Building in New York City. The Clinton Climate Initiative inspired the owner to make the 102-story skyscraper more energy efficient.

Retrofitting a 78-year-old historic icon of architecture is no minor undertaking. The owner of the building assembled a team of specialists, including some of the biggest names in the field.

One of those is Johnson Controls. Clay Nesler is the head of global energy and sustainability for Johnson Controls, and he's been involved with the Clinton Climate Initiative since its inception in 2006. I met with him at Greenbuild to find out what exactly his team expects to achieve, and how.

Denis Du Bois: Clay, you're doing a presentation tomorrow to go over the Empire State retrofit. Now this is a project that owners of existing buildings are looking at thinking, all right, you're going to retrofit the Empire State building. What are you really going to accomplish there, and at what cost?

Clay Nesler: We're actually going to accomplish a great deal. This is a project of a team of experts and we came together and did a very, very extensive analysis of the building from a whole systems perspective. We evaluated over 60 potential improvement measures, all of which would have an impact on energy and carbon reduction for the building.

By combining an analysis of the emissions reduction and a very detailed financial analysis, we zeroed in on the eight improvement measures that, when implemented in the right order and the right way, would result in 38 percent energy savings over the course of the project, as well as have an incremental payback of three years for the building owners.

So we have found the needle in the haystack, if you will. We found a project that's very, very deep energy reductions and efficiency improvements. And also one that has a very, very positive financial return for the owner.

Denis: So what were those top priority measures that gave you the three-year payback?

Clay: It turns out that the most important thing to do was to reduce the cooling load on the building. In the master plan for the building was an additional chiller which was going to be added in its own chiller plant, which would provide additional comfort cooling for the building.

When the building was first built in 1931, they actually didn't air condition the common spaces. When air conditioning was added later in the building, it primarily served tenants, but not the common areas. Obviously, in trying to upgrade the building and bring it to modern standards, that would have required additional air conditioning capacity and cost. By upgrading the windows, going from double-pane glass to super-insulated windows.

"We zeroed in on the eight improvement measures that would result in 38% energy savings..."
--Clay Nesler, head of global energy and sustainability, Johnson Controls

Doing that reduced the cooling load on the building enough that we could get the additional capacity needed by renovating existing chiller plants. Adding variable frequency drives, making them more efficient rather than having to add the additional capacity. That saved tremendously on the capital investments.

We also added insulation behind the radiators, so we were heating the inside of the building instead of the entire island of Manhattan.

Then from there, that significantly lowered the thermal loads in the building, which allowed us to add upgraded and more efficient air conditioning and air handling unit equipment and the controls and all of the other efficient lighting to really get that final 38 percent reduction.

Denis: And when you talked about the windows you used the word "refurbish" not "replace."

Empire State Building
Location: New York City
Retrofit cost: $500 million
Peak demand reduction: 3.5MW
Retrofit completion target: 2013
Floors: 103
Windows: 6,500
Height: 443.2 meters
Original construction --
Commenced: March 17, 1930
Construction cost: $24,718,000
Sources: ESB; DOE

Clay: Absolutely. We're actually putting together a factory in the Empire State building, which is going to rebuild the windows. It's a fascinating process. These are double-hung windows and every night 50 windows will come out and 50 remanufactured windows will go in. The windows that come out will go into the quote factory, where the two existing panes of glass will be recovered and the frame will be reused. A new spacer will be added to the window, which includes a film.

The film is a UV protection, and also provides an additional layer of insulation. That UV protection is actually tuned to the orientation of the building. So it will have different characteristics on the south, where you want to reject as much heat, than it will on the north, where you actually want more light to come in.

The glass will be put back together into the frame, an inert gas will be added, and then the next night, those 50 windows go up. So imagine the diversion from landfill, imagine all the transportation costs of shipping them in and out of Manhattan. It's a very innovative approach which has sustainability benefits even beyond the energy efficiency of the windows.

Denis: You're doing it all on site, and that's a site that is an icon of American architecture, a huge tourist attraction in Manhattan. What are you doing to convey the benefits of this retrofit to all the visitors to the Empire State building?

Clay: We have a great opportunity because millions of visitors visit this building and the sustainable aspects, the energy efficiency and other aspects are certainly over time going to be very prominently presented to the visitors.

One of the neat features is we're adding a tenant energy management system, which is going to meter energy at a floor level or a tenant level and is really going to be the heads-up display, if you will, for the tenants in the building to be able to monitor and reduce their own energy use. That's going to give us the ability to track energy on an ongoing real-time basis across the whole building. So you can imagine that information being displayed along with background on the project.

Outreach and education of the industry, commercial real estate industry and engineering industry is a very strong aspect of this project. The owner just didn't want a great project. In fact he said if this is the only building we do this with, it will not have been a success.

One of his primary goals was to create a replicable model which could be used in large commercial office buildings anywhere in the world. We put in a lot of effort to make sure that the tools and the processes that we develop for this project, which are now all in the public domain, can actually start a revolution if you will in large building deep retrofits around the globe.

"The tools and the processes that we develop for this project, which are now all in the public domain, can actually start a revolution in large building deep retrofits, around the globe." -- Clay Nesler, JCI.

Denis: And that replicable model idea is something I've heard Amory Lovins mention. I understand Rocky Mountain Institute was on that team. Who else was on the team?

Clay: The team included Rocky Mountain Institute, Jones Lang LaSalle, which was the owners rep for the project. Johnson Controls, which operated as an ESCO and technology provider into the project, and the Clinton Climate Initiative.

The genesis for this project was interest by the owner, Tony Malkin, in New York where the Clinton Climate Initiative and the Whole Building Retrofits program was announced. He knew an individual who was a director within in the Clinton Climate Initiative, and said, wouldn't it be great if we put one of our buildings into the program? He suggested a significant building within Manhattan, but one I'll bet most people haven't heard of.

And perhaps the best decision in the whole project was when the Clinton Climate Initiative director said, well, that'd be a great building. We could probably save a lot of energy, but we should really consider doing the Empire State building because of its iconic nature it will truly represent a model for the industry. That was one of the best decisions in the whole project.

Denis: Clay Nesler, Johnson Controls, thanks very much for talking with us.

Clay: Thank you.


I'm surprised they did not try to tear it down. An icon like the Empire State Building should always be kept in great condition