Developer WinnCompanies sought to transform Stone Mill, originally constructed in 1845, into a 21st-century model of energy-efficient adaptive reuse, creating 86 mixed-income apartments. The goal was to develop one of the first fossil-fuel-free, all-electric apartment communities in the state, one that would consume 40% less energy and emit 30% fewer greenhouse gases than a typical gas-fired multifamily building.
The level of energy efficiency that WinnCompanies hoped to achieve with the Stone Mill project typically requires a high-performance, triple-glazed window. However, while triple-glazed windows offer superior thermal insulation and soundproofing, thereby reducing drafts and energy loss, they often conflict with historic preservation guidelines. The state and federal historic tax credit programs were vital to the financing of Stone Mill, so WinnCompanies needed an energy-efficient window that met the exacting historic preservation requirements of the National Park Service and the Commonwealth of Massachusetts to qualify for historic tax credits.
“Universal’s thermally broken triple-glazed windows met the challenge, satisfying historic preservation requirements to match the building’s original windows while meeting the project’s energy performance objectives.”
Christina McPike,
Vice President of Energy and Sustainability at
WinnDevelopment.
WinnCompanies selected Universal Window to meet the challenge. Universal supplied the Stone Mill project with over 400 double-hung, low-emissivity, historic-replica windows from its highperformance, triple-pane 1060 Series. The 1060 Series is an architectural window rated up to 60 PSF for double hung and fixed systems.
“Given New England’s cold climates and high cost for electricity, it was critical to ensure that Stone Mill’s exterior thermal envelope was airtight and robust to maintain a low-energy, comfortable, and durable place to live,” said Christina McPike, Vice President of Energy and Sustainability at WinnDevelopment. “Universal’s thermally broken triple-glazed windows met the challenge, satisfying historic preservation requirements to match the building’s original windows while meeting the project’s energy performance objectives.”
The project was granted both State and Federal Historic Tax Credits. The development’s fossil fuelfree design is also projected to use 46% less energy and emit 33% fewer greenhouse gases than a typical gas-fired multifamily structure. The energy-efficient design, including Universal Windows’ high-performance 1060 Series historic-replica windows, heat pumps, and energy recovery systems, is expected to save 177 metric tons of greenhouse gas emissions each year.
Stone Mill has been the recipient of multiple awards for both energy efficiency and historic preservation, including the 2025 Popular Choice Winner, Sustainable Adaptive Reuse or Renovation Project by Architizer and the 2025 Paul & Niki Tsongas Award by Preservation Massachusetts.
Awards/Designations:
Coming soon.
