The Empire State Building recently completed a major energy upgrade, reducing its greenhouse gas emissions by 54%. This was the result of more than a decade of energy upgrades: between 2007 and 2019, the iconic building reduced its emissions from 34,171 to 15,640 metric tons of CO2 equivalent.
Thanks to the deep retrofit, the Empire State Building now meets Local Law 97 of 2019, which sets emission limits for properties larger than 25,000 square feet. The law takes effect in 2024 and building owners must submit their first report by May 1, 2025. Building emissions are calculated annually and there is a fine of $268 per metric ton of CO2-eq above the limit.
Find out how to reduce your utility bills and emissions with a professional energy audit.
NYSERDA published a highly detailed case study on the Empire State Building energy retrofit that provides valuable information for other building owners, and the project was also covered in a CBC article . As part of the effort to become carbon neutral by 2030, Empire State Realty Trust (ESRT) also upgraded four other properties in its portfolio: 250 W 57th Street, 1350 Broadway, 1359 Broadway and 1333 Broadway.
Insulating windows with inert gases
A high-performance building envelope saves energy year-round, reducing air conditioning costs during the summer and space heating costs during the winter. The Empire State Building has a total of 6,514 double-glazed windows, and all of them have been upgraded with an insulating layer. The insulation layer is composed of mylar film and inert gases (argon and krypton).
The double-pane windows were removed from their frames and cleaned, a mylar film was added between the glass panes, and insulation was further improved by injecting argon and krypton. The window upgrade used 96% of the existing glass and frames, minimizing the amount of waste coming from the Empire State Building. To simplify the project, a complete window factory was set up on the 5th floor.
Elevators with Regenerative Braking
All 68 elevators in the Empire State Building are now equipped with regenerative braking systems, similar to those used by Electric Vehicles . These brakes can generate electricity whenever an elevator is descending and also when ascending elevators stop. In other words, part of the electrical energy consumed by elevators can be recovered and used by other household appliances.
Cooling plant retrofit
Air conditioning is the main electricity expense in most commercial buildings, and this applies to the Empire State Building: a cooling plant is used to cool more than 3.2 million square feet. The chillers were modernized as part of the building modernization and were equipped with an automatic control system to achieve even greater efficiency.
Empire State Building: energy consumption profile
According to the case study published by NYSERDA, the Empire State Building was using 244,011 million BTUs per year in 2019, representing $8,512,325 in annual energy costs. This energy consumption results in a carbon footprint of 15,640 tCO2-eq, which is below the 2024 limit: 24,878 tCO2-eq per year based on the building's usable area.
At the pre-modernization emissions level (34,171 tCO2-eq), the Empire State Building would have exceeded the 2024 limit by 9,293 tCO2-eq, leading to a hefty fine of $2,490,524. Thanks to deep energy retrofit, ESRT will save millions of dollars when LL97 goes into effect.
However, LL97 introduces a much lower emissions limit starting in 2030, and the Empire State Building must reduce emissions below 13,029 tCO2-eq to comply. This equates to an additional emissions cut of almost 17%.
- At the current penalty rate of $268/year, the building would receive a fine of nearly $700,000 per year starting in 2031.
- However, ESRT determined that the Empire State Building can reduce emissions below the 2030 limit with an investment of about $21.7 million.
- The estimated payback period is just 4.25 years, thanks to energy cost savings, maintenance savings and incentives.
The construction sector is responsible for 37% of global emissions, according to the UN. However, buildings produce 70% of New York's emissions, according to the Urban Green Council. Deep energy retrofits can not only reduce energy and gas bills in commercial buildings, but also their carbon footprint.
A professional energy audit is strongly recommended, as a starting point, to identify the measures that produce the greatest energy savings and emissions cuts per dollar invested.
