Multifamily Case Study Library
The Multifamily Case Study Library is a sortable catalogue of documented reports and examples of energy efficiency upgrades in multifamily buildings in the Northeast and Mid-Atlantic region. This tool can help program administrators, architects and contractors, developers, state and local governments, community stakeholders and others identify actionable, real-world strategies for multifamily energy efficiency retrofits. The library also highlights opportunities for further research, particularly in terms of post-intervention performance data.
Case Study Library Overview
Selected case studies are primarily sourced from the 12 states that comprise the Northeast and Mid-Atlantic and Washington D.C., with limited examples from similar climate zones in other US states and Canadian providences. To ensure technical relevance, only studies published after 2019 are included. Featured projects all involve energy efficiency improvements or building electrification, and many projects are deep energy retrofits.
The Library contains over 50 example projects spanning a wide range of building vintages, sizes, and ownership models. Buildings range from historic walk-ups to mid‑century towers and post‑2000 construction, with heights from 4 story residential conversions to large complexes of 300+ units. Ownership profiles range from public housing to mission-driven nonprofits, limited‑equity co‑ops, conventional market‑rate rentals, and mixed‑income developments, illustrating how similar retrofit strategies are being adapted across ownership and financing contexts.
Featured metrics include key details from each case study including date and author, a summary of the building’s physical characteristics, the property’s tenant profiles, project financing details, a comparison of pre- and post-retrofit building systems, and modeled and reported project outcomes including reductions in heating fuel and electricity and overall EUI reductions.
Key Takeaways
- Many projects braid multiple capital sources including utility incentives, green bank or C‑PACE loans, state grants, LIHTC integration, and owner equity to cover up to 40 percent of project costs.
- Pre-retrofit buildings often feature older, inefficient natural gas or fuel oil boilers, window unit air conditioners or aging chillers, poor insulation, and inefficient lighting. Retrofit projects frequently pair heat pumps or high-efficiency boilers with upgraded envelopes, modern ventilation, and efficient lighting and water fixtures. This demonstrates that multifamily properties are moving from old, fossil-fuel-based systems and leaky envelopes to highly efficient, often electrified systems with much tighter shells.
- A significant share of the projects in the Library are at properties serving low- and moderate-income residents, highlighting affordable housing as central to innovation in multifamily energy efficiency.
- Specific measures employed at featured properties vary by building vintage, building system type, and ownership structure, underscoring the need for tailored retrofit paths.
References
Building Energy Exchange. Hi-Rise Low-Carbon Multifamily report and associated case studies (e.g., 172 E 4th St; Roosevelt Landings; Rivermark Apartments; Putnam Square). https://be-exchange.org/report/hi-rise-low-carbon-multifamily
LISC & LISC/RMI. Green Retrofit Initiative and deep energy retrofit case studies (e.g., Hano Homes; Eva White Apartments; Powdermill Village; Nonantum Village Apartments; Aspen Street Cooperative). https://www.lisc.org/our-initiatives/housing/green-retrofit/
NYSERDA. Multifamily decarbonization and retrofit case studies (e.g., Annal Management portfolio; Amalgamated Housing “The Towers”; Carnegie House; Engine 16 Building; Marcus Garvey Apartments; Casa Pasiva / RiseBoro Community Partnership). https://www.nyserda.ny.gov/Residents-and-Homeowners/Case-Studies
New Ecology. Affordable multifamily retrofit case studies (e.g., 808–812 Memorial Drive; Bellevue–Manchester Apartments; Powdermill Village; Nonantum Village Apartments; Hano Homes; Margaret–Bennett Homes; Scrivano Apartments; Carrington Way; Fairweather Apartments; Eva White Apartments). https://www.newecology.org/case-studies-list
Green Bank/PACE Programs. Project case studies (e.g., Montgomery County Green Bank and MD Green Bank projects: 8101 Connecticut Ave; Glen Manor Condos; Hampshire Tower Apartments; Kenwood House Co‑op; Aspen Street Cooperative; Browns Arcade; “Maximum Incentives for Maximum Savings” boiler replacements). https://mcgreenbank.org/case-studies/
Other regional exemplars: CHP Energy Solutions – Princeton Village Apartments; Stone Mill Lofts adaptive reuse; additional mixed‑income and market‑rate multifamily retrofits using C‑PACE, CHP, and deep energy retrofit approaches. https://www.communityhousingpartners.org/princeton-village-case-study-1/; https://retrofithomemagazine.com/2025/01/at-stone-mill-lofts-the-past-present-and-future-of-adaptive-reuse-meet-in-unexpected-ways; https://online.ucpress.edu/cse/article-abstract/8/1/2253451/200753/Decarbonizing-Affordable-Housing-in-New-York
