Local Law 97 & What It Means for Sustainability in NYC

Cities across the US have introduced carbon emissions legislation to do their part to combat climate change. The Big Apple leads the way with the biggest climate change legislation, the Climate Mobilization Act. Local Law 97 is one law within the Climate Mobilization Act that addresses carbon emissions of buildings in NYC to make them more sustainable.

We will discuss Local Law 97 (LL 97), what it means for building owners and managers, affordable housing, and how best to comply with the new directives.

NYC skyline on a sunny day. NYC Local Law 97 will help to make the largest buildings sustainable.

What is Local Law 97

Local Law 97 is a law under the 2019 Climate Mobilization Act that targets carbon emissions from the biggest buildings in New York City. Under Local Law 97, most buildings 25,000 square feet and larger will be required to meet carbon emissions cap, or implement energy efficiency standards, by 2024 in order to avoid significant fines. The carbon emissions cap will continue to tighten periodically. By 2030, most buildings 25,000 sq. ft. and larger will have to reduce their emissions by 40%. By 2050, NYC building emissions will need to be lowered by 80%. Individual buildings’ emissions from 2005 will act as the baseline from which emissions will have to be reduced.

Buildings are the leading contributor to greenhouse gasses and global warming in major cities. By capping carbon emissions from the largest buildings in cities across the world, legislators aim to slow the rate of global warming and reduce estimates of expected temperature increases in the coming decades to avoid worsening natural catastrophes.

Beginning in May of 2025, building owners and managers will have to submit annual emissions reports to prove that their NYC buildings are meeting the new sustainability standards set forth under Local Law 97.

What Does LL 97 Mean for New York City Building Owners

Buildings smaller than 25,000 square feet are exempt from Local Law 97. If you are the owner of a building 25,000 square feet or larger, see below to understand if you are affected by Local Law 97, and if that means you must adhere to carbon emissions caps for your building(s), or if you may opt for energy efficiency measures.

Flow Chart to determine if your building is affected by LL 97 and NYC carbon emissions cap.

If you are the owner of a building in New York City and you must adhere to carbon emission caps for your building to make it more sustainable, then you are subject to fines for failing to do so. Cases of intentionally misreported emissions on the annual Greenhouse Gas Emissions report can be punishable by fine and imprisonment.

To see the amount in fines you would face for your building if you failed to meet the carbon emissions cap, use this NYC LL97 Carbon Emissions Calculator.

Highrises in NYC. Affordable housing can retrofit windows among other energy efficiency measures.

Affordable Housing and Local Law 97

Under Local Law 97, certain buildings that meet the 25,000 square footage threshold to trigger NYC carbon emissions cap requirements have alternatives to meeting the 40% carbon emissions reduction. Local Law 97 Guidance for Affordable Housing outlines which buildings have options available to them. This includes buildings that have at least 35% of its units rent-regulated, among others.

These buildings have the option to prove by December 31, 2024, that they have taken steps to improve their buildings energy efficiency. The Prescriptive Energy Conservation Measures include installing individual temperature controls and air sealing windows.

The combined benefit of all of the listed energy conservation measures will drastically improve the sustainability of large NYC buildings that would otherwise be unduly burdened by carbon emissions caps. Insulating windows, walls, and ceilings and giving residents of these buildings temperature control abilities will go a long way to improving their safety and quality of life.

Thermostat. Under LL 97, buildings will be safer & more sustainable with energy efficiency measures.

Retrofit Windows vs. Replacement Windows

Windows account for 20% of a building’s energy loss. A window upgrade project will go a long way in making your building more energy efficient and compliant with increasingly popular carbon emissions cap legislation, such as Local Law 97.

For window upgrade projects, your options are to retrofit your windows or replace them. Replacing windows means removing every part of the window, frame and all. This is the most invasive, expensive, time-consuming option, and it requires hiring professionals.

When talking about retrofit windows, there are two main options: replacing the window sash or fitting the frames with window inserts. Replacing the sash means the frame stays in place while the moving panels (single, or double-hung) are removed. Replacing the sash is an invasive process, but far less so than window replacement. The parts are more affordable, and a savvy DIYer can complete the project on their own. However, seeking professional assistance is recommended since improper replacement of a window sash can have the opposite effect than the intended energy efficiency upgrade.

Window Replacement Window Retrofit
Type (Entire Frame Replaced) Sash Replacement Window Inserts
Time 1-6 Hours ~3 Hours 15-Minute Installation
Cost $$$ $$ $
Difficulty Professional Required Professional Recommended DIY

Window inserts as a window retrofit project are the most affordable and least invasive option for energy efficiency upgrades. And with Local Law 97 addressing NYC’s largest buildings, the cost, time, and level of invasiveness of energy efficiency upgrades are important factors to take into account. This least invasive retrofit project, as opposed to frame or sash replacement, will allow you to avoid pausing work and life schedules to complete.

Man installing Indow window inserts in NYC. Retrofitting windows makes buildings more sustainable.

Indow & The Clean Fight New York

The Clean Fight New York is a not-for-profit accelerator program in its second year. It was created to identify CleanTech companies and assist them in scaling their products for use in NYC to make buildings more sustainable, in a way similar to that prescribed in Local Law 97. The Clean Fight selects three start-ups each year for each designated area of building energy efficiency. This year the categories are Smart Electrification, Advanced Optimization, and Envelope Efficiency. Indow was the only start-up included in the Envelope Efficiency category addressing energy loss through windows.

4,850 garbage trucks would be needed to haul the 72,0750 tons of carbon Indow inserts have blocked.

With buildings 25,000 square feet and larger requiring drastic measures to reduce carbon emissions and energy usage in compliance with Local Law 97, full window frame or sash replacement is not financially feasible for building owners and managers. The Clean Fight New York is connecting building owners and managers with CleanTech companies, and providing the blueprint for others as they begin the daunting task of making their huge buildings more energy efficient.

Read about the Department of Energy’s study of Indow inserts to learn more about why our inserts were chosen for The Clean Fight New York and how they can help your NYC building become sustainable and meet energy conservation measures under Local Law 97.

Customer Reviews


4.49 Average 1494 Reviews

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Paula S

From start to finish, we were very pleased with our rep, Reed, and the other staff at the PDX will call! The inserts themselves are stupendous! We purchased six total for the noisiest, road side(s) of our home. The outcome was beyond our expectations! Not only did the three rooms that bordered the road become at least 70% quieter, the other end of our home did as well! I cannot recommend Indow inserts more! The technology makes sense to add the inserts rather than purchasing new windows. Great results and thank you! Paul and Paula Spilsbury

Posted 4 weeks ago


Brian was very helpful & informative. He helped me order the correct windows for my needs. They were shipped with the utmost of care & arrived ahead of schedule. Ultimately, the Indow Windows have been very helpful in muffling unwanted noises & they have helped save on our energy costs. Thank you, Indow Window!

Posted 1 month ago

Cynthia M

Very happy with the reduction in noise. Easy to install and use. Great customer service.

Posted 2 months ago

Juli E

We are thrilled with our Indow window inserts! I'd been on the lookout for a more permanent solution to leaky windows in our third floor living space. I discovered Indow on social media but since then have learned of friends who'd had Indow recommended to them by their rennovation contractor. The entire process went smoothly with friendly reps at hand to talk through questions during measuring, etc. They fit perfectly and help us to maintain the beautiful design of the windows on our 100 year old home! Highly recommend!!

Posted 3 months ago

Jen F

Worth the money!

Posted 3 months ago

Elizabeth H

For townhouse living, this solved my problem with noise from my neighbor's with my kitchen window. A considerable decrease of noise indeed! Measurements were a bit frustrating so I recommend using a laser measurement device and following directions to use a string for the diagonal. They look great and were easy to push into place. I highly recommend as an alternative to buying a new window.

Posted 4 months ago


Easy to install, and instantly stopped drafts and dampened outside noises very effectively!

Posted 4 months ago

Robert C

The process could've been smoother with the sending of the measuring kit. There was a delay with weather in Oregon but then it felt like my kit was still delayed due to other reasons. Most new homes (like mine) have textured paint and it can also be inside your window frames. I measured everything out but I still have little tiny gaps due to the texturing. Not indows problem but just be aware you made need to sand or fill in those gaps yourself to get a perfect seal. I did the acoustic grade inserts and they have reduced some noise but they will not completely block or significantly reduce road noise. This is most apparent with deep or lower frequencies like truck exhausts or modified street racing cars that are quite popular these days. Taking the inserts out to open your windows isn't an easy task. The little metal hook they provide needs to be either bigger or you can attach something to it as a way to leverage yourself. Overall the process was average. I think they're definitely a good option for weatherproofing and some sound reduction depending on the type of windows you have. I would purchase again.

Posted 4 months ago

Shelley C

The process for ordering and installing the Indow Widnow inserts was so easy. They sent the measuring information and it had great instructions. The inserts were delivered by UPS was crushed on one corner, but the company had packed them well, so there was no damage. We installed them the same day. It works best if you have two people completing the installation. We felt the results immediately and are glad we spent the money to make our home just a little more efficient.

Posted 4 months ago

Barry B

The insert fits like a glove and insulates the window! No more frost and condensation on the interior of the window! Thank you for an easy, effective and attractive fix!

Posted 4 months ago

Susan A

The support during the entire process was wonderful, thank you so much for the extra quiet space!

Posted 4 months ago

Volodymyr R

Very good good quality. Overall very satisfied with this product and service. Thanks

Posted 4 months ago

Jane H

Our home was built in 1913 and has beautiful old wavy glass single-paned windows. I’m so glad we were told about Indows and didn’t have to replace the original windows. We live in Canada but had no difficulty placing the order and were very impressed by how accurately the company met its deadlines, including cross border delivery. The Indows inserts blend in perfectly with our home and the existing window frames. You don’t see them unless you’re actually looking for them. But what we did notice was how much warmer the rooms feel the minute the inserts were installed! I can’t speak to any heating bill savings because they just went in this week, but our home feels much, much cozier. Our contractor who took all the measurements and installed the Indows says: “Excellent instructional videos: clear and informative. Very impressed with the design and the product. Overall, the ease of installation is quite impressive. Working with all the staff at the company was great – everyone was very helpful.” I’m already recommending this company to any of my friends who live in drafty older homes and want to reduce their heating/cooling bills and do some good for the environment.

Posted 5 months ago


Don't be afraid of buying an older home with single pane windows. This company has you covered. Their inserts are super high quality and fit well thanks to the laser measuring kit they send. Highly recommended!

Posted 5 months ago

Katie M

We purchased three Indows to reduce drafts and noise in our bedroom, which faces the street. The improvement was immediate. Our house was built in 1958 and although we have exterior storm windows we didn't want to replace the windows outright due to cost and architectural consistency. These were an excellent solution.

Posted 5 months ago