A recent report from a graduate urban planning studio class at Rutgers University examines the challenges and opportunities of decarbonizing low-to-moderate-income multifamily buildings in New York City. The study was prepared for the New York City Department of Buildings and focuses on the implementation of Local Law 97 (LL97), which mandates significant reductions in greenhouse gas emissions from large buildings.
Buildings are responsible for more than 70% of New York City’s greenhouse gas emissions, according to city data. LL97 sets strict emission caps for large buildings, aiming to cut building sector emissions by 40 percent by 2030 and 80 percent by 2050. While this law is central to the city’s climate goals, its implementation poses particular difficulties for rent-regulated and income-restricted housing. These properties often have aging infrastructure, limited access to capital, and affordability restrictions that make it hard for landlords to invest in retrofits.
The report recommends several policy changes to help these buildings comply with LL97 without threatening housing stability. Suggestions include allowing block-level compliance in low-income areas, creating tailored timelines for Section 321 properties, and expanding financial support for deep retrofits. “To ensure that LL97 implementation does not jeopardize housing stability, this report recommends allowing block-level compliance in low-income areas, establishing tailored timelines for Section 321 properties, and expanding financial support for deep retrofits,” the authors state.
The analysis finds that electrifying space heating combined with envelope upgrades—such as improved insulation and window replacements—is essential to meet the city’s 2030 targets. However, while basic weatherization measures are more affordable and widely supported by funding programs, window replacements remain expensive and technically challenging in older multifamily buildings.
The report also highlights that rooftop solar installations on individual buildings provide only marginal emissions reductions due to limited space. In contrast, shared community-scale solar systems at the block level could generate up to 18% more energy than total demand and reduce grid imports by over half. This approach offers a scalable path toward net-zero compliance in dense urban neighborhoods.
Pre-war and post-war multifamily buildings face different retrofit challenges because of their heating system designs. Pre-war buildings typically use steam-based heat distribution systems that are less efficient and harder to electrify compared to hydronic or forced-air systems found in newer structures.
Policy recommendations call on the NYC Department of Buildings to develop phased inclusion plans for certain property types and pilot programs focused on shared infrastructure retrofits like geothermal systems or district-scale solar power. Incentives should prioritize both emissions reductions and cost savings while integrating with state and federal programs.
The research team used geospatial analysis, energy modeling, and policy review methods—including mapping rent-regulated housing risks using MapPLUTO data—to assess retrofit scenarios’ feasibility from both technical and equity perspectives.
The student authors are Adnan Zia, Annabelle Simhon, Maham Khurshid, Shuhan Lei, Keiya Satoh, and Joseph A. Brosnan. The project was prepared under the guidance of an instructor with liaison Ioanna Tsoulou representing the Department of Buildings.
