UNION legacy
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2024 | Somerville, Massachusetts
5,110 SF | Main Unit | 4 Bedrooms | 3 ½ Bathrooms
Passive House inspired Net ZeroUnion Legacy is a new two-family residence in Somerville completed in 2024. The project increases housing density while maintaining the scale and proportion characteristic of Somerville’s residential typology. From the street, the building reads as a single, well-composed home. Behind that restraint is a carefully integrated structural and performance strategy developed in response to both site and client priorities.
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The site sits within a high water table, making the creation of finished lower-level space technically demanding. At the same time, the program required two independent dwellings on a tight urban lot that needed to feel aligned with the surrounding neighborhood fabric.
The objective was clear: add density without amplifying scale, achieve net-zero energy performance, and build durable, comfortable space below grade — all within a coordinated and predictable process.
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The massing is composed as a single, unified volume rather than an expressed duplex. Roof geometry supports on-site solar production while reinforcing the rhythm of nearby houses. Window placement was calibrated to bring substantial natural light deep into the interiors, creating layered, spatially rich rooms without excess ornament.
Below grade, insulated concrete forms (ICF) provide structural continuity and thermal stability within groundwater conditions. A 2,000-gallon subsurface water storage system mitigates hydrostatic pressure while supporting greywater reuse — transforming a site constraint into managed infrastructure.
Above grade, the enclosure was designed as a vapor-open assembly to support long-term drying and durability. Ventilated cladding and roofing systems further enhance resilience. Advanced framing techniques reduced redundant lumber and increased insulation depth, improving both energy performance and construction clarity.
Structural spans were maximized within wood framing limits, eliminating the need for steel beams or interior columns and allowing open, flexible interior volumes.
The building was designed and tested to meet Passive House performance standards, though formal certification was not pursued. WUFI Energy modeling informed insulation levels, window orientation, and mechanical sizing throughout design development. A balanced ERV system and a hybrid ducted/ductless mechanical approach allowed equipment to be carefully matched to the home’s actual energy demand.
Material selections emphasized durability and drying potential. Solid timber components were used wherever possible in place of more resin-heavy composites, and high-VOC materials were greatly minimized or eliminated in both assemblies and finishes.
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Union Home reflects an integrated design-build process shaped through ongoing dialogue between the owners, the Group Design Build team, and key trade partners. Performance targets and structural strategies were refined collaboratively, aligning energy modeling and cost with constructability early in the project.
Detailed framing drawings were developed prior to construction, reducing field improvisation and streamlining execution. By resolving structural spans, enclosure assemblies, and mechanical systems in coordination — rather than in sequence — the team maintained clarity around cost, schedule, and performance.
The result was a home that feels measured and composed rather than experimental.
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Item descriptionUnion Home demonstrates that high-performance, context-sensitive housing can be both technically rigorous and architecturally restrained. It increases density while reinforcing neighborhood character, achieves net-zero energy through intentional geometry, and delivers durable finished space within challenging groundwater conditions.
More broadly, the project affirms a core principle of Group Design Build: when design, modeling, and construction knowledge move together — and when clients and trades are part of that process — ambitious performance goals become controlled and buildable.
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We hired Group Design Build for our custom, ground up multi-family dream home in the middle of a dense urban neighborhood. There were many challenges along the way, but we could not be happier with the architecture or prouder of the construction results. The quality, craftsmanship, attention to detail & communication throughout the entire process was second to none. We thank Tagore, his talented team of skilled workers and sub-contractors for making this project a reality.
GBD is a high integrity firm that we strongly recommend.
Dan & Penny M.
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