Business Details
29 Years
experience
Award-Winning Sustainable Architecture & Design Solutions
Since 2005, Onion Flats has established itself as a leader in sustainable architectural design, delivering high-performance buildings that prioritize energy efficiency, resilience, and community impact. Our team combines decades of hands-on experience in architecture, construction, and development with specialized expertise in Passive House and LEED certification. We approach each project with an integrated design philosophy, leveraging our in-house capabilities to ensure seamless execution from concept to completion. Our commitment to innovation is evident in our pioneering work with modular construction and deep energy retrofits, which address the urgent need for decarbonizing existing buildings. We serve clients across the Northeast, offering tailored solutions that balance environmental stewardship with practical affordability.Our track record includes groundbreaking projects like the nation's first LEED Platinum duplex and Pennsylvania's first International Passive House Award-winning development. As both architects and developers, we maintain a unique perspective that aligns design excellence with real-world feasibility. Our team's credentialsincluding multiple Certified Passive House Consultants and Tradesmenreflect our dedication to advancing industry standards. We remain focused on creating buildings that not only meet today's sustainability challenges but also set benchmarks for future generations.
Services
Architectural Design
Sustainability Consulting
Passive House Certification
Modular Construction
Deep Energy Retrofit
Details
- Year established: 1997
Highlights and features
- We have over 25 years of combined experience in sustainable architecture and construction.
- Our team includes Certified Passive House Consultants and Tradesmen.
- We offer integrated design-build expertise through our sister company JIG, Inc.
- We pioneered the nation's first LEED Platinum duplex and Pennsylvania's first Passive House project.
- Our proprietary DER feasibility tool streamlines energy retrofit planning and cost analysis.
Associations and certifications
- LEED AP
- CPHC
- CPHD
- Phius-certified
What people say
Seasoned professionals
Sustainable design expertise
Collaborative, meticulous approach
Award-winning projects
Deep technical knowledge
Services
Architectural Design
Our architectural design services combine creative vision with technical precision to create functional, sustainable spaces. We specialize in new construction and adaptive reuse projects that prioritize energy efficiency and community impact. Our integrated approach ensures seamless coordination between design and construction phases for optimal results.
Sustainability Consulting
We provide comprehensive sustainability consulting grounded in decades of experience with LEED certification and Passive House standards. Our team helps clients implement cost-effective, low-tech solutions for high-performance building envelopes. We focus on practical strategies that maximize environmental impact while maintaining affordability.
Deep Energy Retrofit
Our deep energy retrofit services specialize in transforming existing buildings into high-performance structures with 80%+ energy reductions. We offer full lifecycle support including feasibility analysis, design, and construction administration. Our proprietary DER costing tool helps clients evaluate retrofit options early in the planning process.
Modular Construction
We leverage our 20+ years of modular construction experience to deliver efficient, scalable building solutions. Our services include modular planning, manufacturer selection, and site suitability analysis. By integrating Passive House principles, we ensure high-performance outcomes through off-site construction methods.
Passive House Certification
As one of the most experienced Passive House firms in the US, we offer certification consulting for residential and commercial projects. Our team includes multiple Certified Passive House Consultants and Tradesmen who guide projects through the rigorous certification process with proven expertise.
People
Timothy McDonald
Principal Architect
Licensed architect with 25+ years of sustainable design experience. Co-founder of Onion Flats and JIG, Inc. Certified Passive House Consultant and LEED AP. Combines technical expertise with teaching experience to deliver resilient, low-carbon solutions.
Howard Steinberg
Principal Architect
Registered architect with 30+ years of Mid-Atlantic experience. Co-founder and leader of complex projects. Certified Passive House Designer and LEED AP. Known for strategic foresight and client-focused solutions in high-performance building delivery.
Kara Haggerty Wilson
Design Director
Registered architect specializing in affordable housing and institutional projects. Certified Passive House Designer with expertise in energy modeling. Translates sustainability goals into actionable strategies through collaborative design processes.
Dan Addis
Project Manager
Experienced project manager handling diverse project types from restaurants to commercial developments. Specializes in construction administration and field coordination. Brings hands-on expertise to ensure project success from start to finish.
Jeannette Penniman
Project Manager
Registered architect with expertise in education, residential, and historic retrofit projects. Certified Passive House Consultant focused on low-carbon strategies. Active member of BuildGreenCT promoting sustainable regional practices.
Questions
What architectural services do you specialize in?
We specialize in sustainable architectural design, Passive House certification, deep energy retrofits, and modular construction solutions.
Do you work on residential and commercial projects?
Yes, we handle both residential and commercial projects including multi-family housing, institutional buildings, and adaptive reuse developments.
Are you certified in green building standards?
Our team includes LEED Accredited Professionals and Certified Passive House Consultants/Designers with extensive project experience.
What areas do you serve?
We primarily serve the Northeast United States with offices in Philadelphia and Manchester, Massachusetts.
Can you help with building energy retrofits?
Yes, we're leaders in deep energy retrofits with proprietary tools and extensive experience achieving 80%+ energy reductions.
Do you offer construction management services?
Through our sister company JIG, Inc., we provide integrated design-build services and construction management solutions.
Reviews (1)
Erin Berry
Jul 28, 2021
Report
Care to comment on the L&I zoning permit dated 7/22/21 for full demolition of the bank building at 1952-58 Front Street, after you said this right on your website? "Onion Flats Architecture recognized the importance of maintaining the character of these unique structures, though it was not financially feasible to restore them to their original… historic condition. In an effort to save these landmarks, the structures are being stabilized and the primary architectural details restored in order to treat the buildings as artifacts within which the new program will be inserted."
