Millennium Partners Secures $281 Million PACE Financing for Winthrop Center in Downtown Boston
BOSTON — Millennium Partners, Nuveen Green Capital, and MassDevelopment have closed $281 million in Commercial Property Assessed Clean Energy (C-PACE) financing for the Millennium Residences at Winthrop Center, a 62-story mixed-use tower at 115 Federal Street in downtown Boston. The transaction, announced Aug. 14, 2026, is the largest commercial PACE financing ever completed in New England.
The deal recapitalizes the completed development using fixed-rate, long-term private capital structured as a betterment assessment on the property rather than conventional mortgage debt. Nuveen Green Capital served as capital provider, with MassDevelopment administering the financing under the state's PACE Massachusetts program in consultation with the Massachusetts Department of Energy Resources.
Deal Structure and Capital Stack
The $281 million in C-PACE financing is structured as a fixed-rate instrument with a term of up to 20 years, repaid through a betterment assessment on the property's tax bill. Because PACE assessments are not recorded as conventional recourse debt on the borrower's balance sheet, the structure offers Millennium Partners a way to access permanent, lower-cost capital post-completion without adding traditional mortgage debt.
Michael Doty, Senior Director of Originations for Nuveen Green Capital, described the transaction's mechanics. "Through C-PACE's accretive financing structure, Millennium Partners was able to recapitalize this project post-completion with secure long-term, low-cost, fixed-rate capital, effectively injecting liquidity back into the property," Doty said.
The proceeds allow Millennium Partners to monetize the building's energy-efficiency investments and extend the financing term, replacing or augmenting shorter-duration capital with permanent debt tied to the asset's green credentials. Nuveen Green Capital has originated more than $6 billion in sustainable commercial real estate financing and is an affiliate of Nuveen, the asset management arm of TIAA.
About Winthrop Center
Winthrop Center, developed and owned by Millennium Partners, is a 62-story mixed-use tower completed in 2023 at 115 Federal Street in Boston's Financial District. The building includes approximately 800,000 square feet of office space, 317 luxury condominium residences, below-grade parking, and The Connector, a multi-level public gathering space. The office portion — marketed as the world's largest Passive House-certified office building — is classified as Class A space. The residential component, branded as the Millennium Residences at Winthrop Center, occupies the upper floors of the tower.
The development has earned LEED Platinum and WELL Gold certifications. The Passive House standard is a building performance benchmark designed to significantly reduce energy consumption, particularly for heating and cooling. Massachusetts Department of Energy Resources Commissioner Elizabeth Mahony stated that Winthrop Center is projected to use 65 percent less energy than comparable, non-energy-efficient buildings in the region.
Winthrop Center was financed during construction by Cale Street Partners.
Statements from Key Parties
Christopher Jeffries, founder of Millennium Partners, framed the transaction as recognition of the firm's long-term sustainability commitments. "Winthrop Center is a reflection of that commitment, and this financing through the PACE Massachusetts program recognizes the investments we have made in energy efficiency while providing long-term capital that supports the building's enduring performance," Jeffries said. "We are proud to partner with MassDevelopment and Nuveen Green Capital on a transaction that demonstrates how innovative financing can help advance the future of sustainable development."
Navjeet Bal, President and CEO of MassDevelopment, called the deal a milestone for the state program. "We congratulate Millennium Partners and Nuveen Green Capital on today's transaction and encourage developers and property owners across the state to explore how this financing tool can help them advance clean energy investments, lower building emissions, and save money," Bal said.
Massachusetts Governor Maura Healey, Lieutenant Governor Kim Driscoll, Boston Mayor Michelle Wu, and Economic Development Secretary Eric Paley also issued statements supporting the transaction, citing its role in reducing building energy costs and advancing the state's climate goals.
PACE Massachusetts Program Context
PACE Massachusetts is administered by MassDevelopment in consultation with the Massachusetts Department of Energy Resources. The program enables commercial property owners to finance energy-efficiency and renewable energy improvements — including solar panels, heat pumps, geothermal systems, efficient lighting, and insulation — through long-term assessments on the property rather than traditional loans. Financing terms of up to 20 years are available.
Municipalities must opt into the program by majority vote of the city or town council or board of selectmen. As of the announcement date, 89 cities and towns in Massachusetts, including Boston, have opted in.
In June 2026, MassDevelopment and the Department of Energy Resources updated the program's guidelines for new construction properties, setting financing levels based on compliance with local building energy codes, expanding eligibility for allowable costs, and streamlining application and approval processes.
Founded in 1991, Millennium Partners has developed mixed-use properties in urban markets across the country. In Boston, the firm's prior projects include Millennium Tower and Millennium Place, both in the Downtown area.
Market Context
The Winthrop Center recapitalization comes as Boston's office market contends with elevated vacancy. Greater Boston office vacancy stood near 18.5 to 19 percent as of mid-2026, with asking rents declining modestly year-over-year. Boston's CBD vacancy was approximately 22.5 percent as of the second quarter of 2026, reflecting the broader market's absorption of pandemic-era demand shifts.
Winthrop Center is one of several major new Class A office towers that have delivered in Boston's CBD in recent years, alongside South Station Tower and 10 World Trade, collectively adding approximately one million square feet of new supply to an already soft market. Newly delivered Class A product in the CBD has recorded positive net absorption even as older Class B and Class C stock remains largely vacant — a dynamic that positions trophy, green-certified buildings like Winthrop Center as beneficiaries of tenant flight to quality.
The C-PACE structure, which provides long-term fixed-rate capital without conventional recourse debt, offers a financing mechanism suited to the current environment, where traditional permanent office financing has become more expensive and conservative.