On Earth Day, New York City Mayor Bill de Blasio announced plans for a Green New Deal that aims to reduce carbon emissions in the city by introducing legislation to “ban inefficient all-glass buildings.” One such piece of legislation is the Climate Mobilization Act, passed by the New York City Council on April 18, which aims to reduce the greenhouse gas emissions by 80% from large- and medium-sized buildings in the city by 2050.

The legislation establishes an Office of Building Energy Performance which oversees the development, implementation and coordination of building energy performance legislation and policies for existing buildings, new construction and major renovations. It also requires that the office create annual building energy assessment protocols, require building owners to submit these assessments, validate these assessments and determine penalties for buildings that are noncompliant with applicable energy limits. However, the legislation makes no specific mention of glass.

“By May 1, 2023, and by May 1 of every year thereafter, the owner of a covered building [defined as those that exceed 25,000 gross square feet] shall file with the department a report, certified by a registered design professional, that for the previous calendar year such building is either: In compliance with the applicable building emissions limits established pursuant to section 28-320.3 or not in compliance with such applicable building emissions limits and the amount by which such building exceeds such limits,” reads the legislation.

When the Green New Deal was announced, Mayor de Blasio criticized what he called inefficient, all-glass buildings that do harm to the Earth. Glass industry experts have since weighed in with their thoughts on the plan, including Yago Martinez, Interpane’s business development manager for North America. His company worked on some of the buildings in the Hudson Yards development, which de Blasio cited as examples of what not to do.

Martinez says they don’t see the proposed Green New Deal as an attack on glass facades, but on the way that current energy codes allow them to be inefficient.

“Ever since I started working on U.S. projects I have been surprised at how low the performance requirements are, and how little effort is made to adopt technologies that not only make glass facades more efficient, but have also been on the market for many years and are well known and proven in other countries,” says Martinez. “Most of the glass we supply in Europe is triple-glazed, with high-performance coatings and Argon or Krypton filling; U-values of 0.18 btu/sqf*hr*F or lower are not hard to achieve.”

“Glass is a great material for buildings … and it can also perform incredibly well when used right. Argon-filled triple glazed units should be the new standard, and more efforts should be put into enhancing even more façade systems like double-skin walls. A good example would be the Jerome L. Greene Science Center at Columbia University’s Manhattanville Campus,” he continues.

Martinez says that the industry needs to do more, but that as glass manufacturers it’s not really in their hands.

“We promote better, more efficient solutions, and we keep developing better coatings, but the overall cost is also higher, so the decision is not ultimately on us,” he says. “For American projects we started giving Argon as a free upgrade a few years ago because otherwise, most of them would have been ordered with an air interspace, and the performance is substantially better with Argon …We accept and embrace the challenge.”

The American Architectural Manufacturers Association (AAMA) supports New York’s push for more energy efficient products and buildings, according to technical director Steven Saffell, especially for existing buildings where energy efficiency upgrades would have a positive impact on the building’s energy consumption and the comfort of occupants.

“Most new and existing products can be designed or retrofitted to meet even the strictest of current energy codes. Existing technologies such as low-E glass, high-performance spacer systems, multi-pane insulating glass units and new emerging technologies can be employed to improve energy efficiency of not just the products, but also the entire building,” he says. “Additionally, the positive impacts of windows, doors and skylights are immense. Fenestration connects us to our environment with views that improve attitudes, increase productivity, provide ventilation and more.”

Saffell says that building codes set minimum standards and are in place to help move the industry toward safer and more acceptable society norms.

“When so much attention is placed on a single attribute, or building system in this case, a whole system approach to improve building efficiency is lost. The focus must be on the improved efficiency of the entire building, including the glass,” he says. “The technology exists today to make our building envelopes and entire buildings much more energy efficient.”

Deb Callahan, CEO of the National Fenestration Rating Council (NFRC), says the full impact of the plan will depend on the details and implementation.

“… but NFRC has spent 30 years developing standards and testing requirements to make windows as efficient as possible. Bold policies like this can have a large impact, so it’s important to have the best data to get the best results. To the extent that policymakers and industry want to install more efficient fenestration products, we’d be happy to assist in that conversation,” she says.

Helen Sanders, strategic business development at Technoform North America, says that efficient glazing technology already exists.

“In the façade community, we know that highly glazed facades can already be designed to meet high energy performance levels. The technology is available, it just needs to be specified and building owners need to be willing to make the higher cost investment,” she says. “The PNC Tower is an example of such a high-performing building with a double skin curtainwall. There are examples in the extreme Canadian climate, as well as in Europe. I recall even ten years ago being told that 80% of the curtainwall systems being delivered from one of the global curtainwall contractors were double skin. Unfortunately, most of those were not going in to the U.S.”

“While attention-getting, this legislation doesn’t actually ban highly glazed facades; it would require them to meet more stringent energy performance requirements. As a result, this has the potential to be good for our industry by increasing the adoption of high-performance aluminum and insulating glass solutions that are already available,” she continues. “High-performance solutions will need to include some or all of the following:  wide, complex, aluminum thermal breaks; double skins; multi-cavity insulating glass, high-performance warm-edge spacers and glass coatings; and dynamic shading or glazing. More stringent energy performance requirements also should be good for the building occupants, making their environments more thermally and visually comfortable when sitting next to these façades.”


  1. I completely agree with the comments in this article from people we know, respect and work with. We have installed several dual skin facades over the years, including one here in New York City. It requires both the technical know how as well as the commitment from the design team and the client. I think the 800 pound gorilla in the room that is not addressed is that someone has to pay for these changes in the way building skins are designed, manufactured and installed. That cost could be recouped over the life of the building (or sooner) from lower energy costs resulting from increased performance. However, not all owner / developers take the long term view on this issue. The impact on our industry is yet to be fully understood and will be based as Deb Callahan said on the details and implementation. More communication with all parties involved is really required to make sure that these changes are done in an intelligent way that doesn’t damage the very industry that will be required to implement the changes.

  2. It is good to see NYC making a commitment to reduce GHG’s. As noted above, this technology is available today. Glass is definitely an important factor in envelope performance. But if you put great performing glass in a poor performing frame, your results are mediocre at best. As an industry we need to focus on assembly performance. High performance framing with high performance glass (which includes spacers and fill in the air space) will take us to the next level. Using NFRC as a base line, we are currently modeling assemblies that are attaining R 6.7.

  3. We believe that the most innovative solution is already available, tempered Vacuum Insulated Glass, tVIG, LandVac, R15 single glazed and R18 in a Hybrid. Initiatives like this will accelerate the adoption of this high performance technology. On top of the energy conservation you have the acoustic performance, fundamental for comfort in an urban environment. We are already working on a few projects (confidential) to retrofit historical buildings in NYC and the Midwest. Martin Bracamonte, President, VIG Technologies

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