Case Studies


Helping to Enable the Zero-Carbon World.

Thermal Optical Window Insert Case Study:


Newmark on behalf of United Methodist Women


777 United Nations Plaza, NY, NY


67,177 square foot, 12 story, commercial office building constructed in 1963 with single-pane aluminum frame windows.

Utility: The building is served by a down state NY electricity, natural gas and district steam utility. A 300-ton on-site steam-driven, absorption chiller generates chilled water for the building and hot water needs are met by a steam heat exchanger. Additionally, the building is served by a mix of air handlers and fan coil units.
Project Description: In June of 2022, IEG completed installation of 296 custom sized thermal optical window inserts directly onto the interior of the existing glass and frame in floors 2 through 12 of the building with the intent to reduce infiltration while simultaneously improving the thermal and transmittance characteristics of the window assemblies, resulting in significant energy savings from reduced cooling load in the summer, less heating needed in the winter, street noise reduction and increased occupant comfort.

Thermal Optical Window Insert Case Study:

Pre-Install Annual Consumption Baselines:

7,302 Mlbs of Steam
610,800 kWh of Electricity

3rd Party Energy Model Predicted Savings:

20% Steam
17% Electricity

One Year Post-Install Consumptions:

5,257 Mlbs of Steam
482,400 kWh of Electricity

One Year Post-Install Savings:

28% Steam
21% Electricity

777 United Nations Plaza

Utility’s Preliminary Incentive Offer:


One Year Post M&V Actual Incentive:


Performance Based Incentive Increase:


1st Year Post Install Realized Bill Savings:


LL97 Penalty Reduction Through 2039:


(Pre and post consumption data compiled from customer provided utility bills)
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