“We have engaged Onion Flats on projects large and small. While their experience and creativity as an architect is excellent, the fact that they have developed their own projects and are experts in Passive House and Net Zero construction has made them invaluable to us.”
-Rob Fluehr, VP of Residential Development, The Goldenberg Group
Meet the Team
Timothy McDonald
Principal
RA / LEED AP / CPHC / CPHD
Timothy is the President and CEO of Onion Flats LLC, and a licensed architect in Pennsylvania and New Jersey. In 1997, with his brother Patrick, he co-founded Onion Flats LLC. Tim has been an adjunct Professor of Architecture at Philadelphia University, Temple University, University of Calgary, and University of Pennsylvania. His service and experience extends into his community by holding current positions in the Northern Liberties Neighbors Association Zoning Committee, the Philadelphia Sustainability Advisory Board, as well as a previous position on the Old City Civic Association Board of Directors. Tim is also Founder/President of FAARM, a non-profit organization dedicated solely to the exhibition of art and architecture in Philadelphia.
As a partner in Onion Flats, Tim’s role is Lead Architect and Construction Manager. In 2005, Tim and his brothers Pat and John, in conjunction with Howard Steinberg formed the architecture firm Plumbob, LLC and JIG, Inc., a General Contracting, Construction Management and Green Roof company, allowing this team to provide full design-build services for both clients and their own developments. Additionally, Tim is a Certified LEED Accredited Professional and Passive House Certified Consultant and Tradesman.
Howard Steinberg
Principal
RA / AIA / LEED AP / CPHD
Howard is a registered Architect in Pennsylvania, New Jersey, New York, Delaware, Maryland, and Virginia. Holding degrees in Environmental Design, Architecture and Construction Management, he has worked for several architectural, construction management and development firms since 1991, and served as VP of Design and Construction for Scannapieco Development and Switzenbaum Realty Capital.
In 2005, Howard joined Onion Flats with partner Tim McDonald, and JIG, Inc., a General Contracting and Construction Management / Certified Green Roof design and installation company allowing the Onion Flats team to provide full design-build services for both clients and their own developments. Additionally, Howard is a Certified LEED Accredited Professional, Certified Passive House Designer and Tradesman.
John McDonald
Principal
Eco-Broker / Realtor
John is the Chief Operating Officer of Onion Flats LLC, and a licensed realtor in Pennsylvania. His responsibilities include land acquisition, project financing, management of the administrative and accounting departments, occupancy and site management for all investments properties, publicity, marketing and sales. In 2005, John created a joint venture with his brothers to develop all future projects. Additionally, as a licensed Cityspace realtor, John is the exclusive sales agent for Onion Flats projects in addition to servicing his book of base clients. He has been awarded Prudential’s Top Of The Rock Sales Award in both 2005 and 2006 which recognize his sales are in the top 3% of all agents nationwide. John was honored in 2009 by the Philadelphia Business Journal as one of their 40 UNDER 40 Award winners.
Kara Haggerty Wilson
Senior Project Manager
RA / LEED AP / CPHD
Kara joined Onion Flats in 2017 and is a registered Architect in Pennsylvania as well as a Certified Passive House Designer. Kara’s work experience with affordable housing and institutional projects, as well as her experience in energy modeling and passive house design, has supported Onion Flats’ own development projects as well as their high-performance building designs and passive house consulting efforts for clients.
Patrick McDonald
Principal
LEED AP / GACR
Acting as the Vice President of Onion Flats, Patrick is also a registered Master Plumber in Philadelphia, as well as a certified Operating Engineer of heavy equipment. He is a co-founder of Onion Flats LLC with his brother Tim. He brings twenty-seven years of mechanical trades’ expertise to the company’s projects. Additionally, he has the operations and management experience of owning a plumbing, heating, and excavation company since 1985 with which he serviced contracts for the United States Naval Shipyard, SEPTA, and included the surrounding municipalities Aston, Haverford, Middletown, and Radnor Townships.
Pat is accountable for the mechanical systems of Onion Flats’ projects. He has also been the catalyst in the company’s decision to take on sustainable building practices and renewable energy, and is a Certified Solar Panel Installer and a LEED Accredited Professional. Additionally, Patrick is a Passive House Certified Tradesman.
Dan Addis
Project Manager
NCARB
Dan joined Onion Flats in 2013 and has worked on a variety of project types for the firm including, single-family homes and renovations, restaurants, schools, rehearsal spaces, high-performance multi-family affordable housing, and large Passive House commercial mixed-use projects. Dan is heavily involved in project detailing, trade coordination, and Construction Administration at Onion Flats and as a result, spends a lot of time on the phone and in the field with the project team ensuring those efforts are successful.
Jeannette Penniman
Project Manager
RA / LEED AP / CPHC
Jeannette joined Onion Flats in 2023, following experience with firms in Pennsylvania and Connecticut focused on a wide range of work: higher education, K-12 education, multifamily and single family residential, historic retrofits, and adaptive reuse. Throughout, Jeannette has worked to integrate high performance and low-carbon design principles into all projects, and has managed Passive House certification for a variety of project types as a Certified Passive House Consultant. Jeannette is a Registered Architect in Connecticut and is heavily involved in BuildGreenCT - Connecticut’s central organization for a just and sustainable built environment.
Ben Allee
Project Manager
NCARB, ASSOC AIA
In 2020, Ben joined Onion Flats (OFA) as a project manager. Since then he has worked on over nine Deep Energy Retrofits (DERs) and managed Hano Homes into the construction phase as a pilot project for the Boston Mayor’s Office of Housing. He has worked on Net-Zero, DERs, and Passive House multifamily projects from six to 600 units. Ben helps OFA with advancing their uses of technology. He is a member of local Revit and Bluebeam user groups. Ben spearheaded the research and implementation of lidar scanning techniques for DERs to improve project speed and accuracy.
Before OFA, Ben worked in diverse locations ranging from Australian prefab, Texas prefab, and projects in the Alaskan arctic. His museum exhibition design work has won a Graphis Award in his role with the Anchorage Museum design department.
See some of his renderings on the Morris Steel project.
At the time, brothers Tim and Pat McDonald purchased a 200 year old, five story building in the Old City section of Philadelphia.
In 2005 as brother Johnny McDonald, and longtime friend and architect Howard Steinberg joined the team, Onion Flats became more serious about its play. With this new structure in place, the firm began to push the boundaries of sustainable urban development, completing the first LEED Platinum projects and then beyond to Passive House and Net-Zero-capable in the region, and even country. In addition to our own developments, we began providing innovative solutions to like-minded clients.
Today, we return to our roots to provide greater opportunities to holistically serve our clients, collaborate with our partners, and grow an even greener future for Philadelphia and beyond.
Onion Flats began in 1997
