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PHIUS Technical Committee Members

Ryan Abendroth

Principal, Passive Energy Designs LLC

Ryan Abendroth is an experienced Certified Passive House Consultant (CPHC®) and the former Certification Manager at Passive House Institute US (PHIUS). He has worked on hundreds of passive house projects including small residential designs and student projects to mid-sized commercial and non-profit developments, and he has been at the forefront of research and design in passive houses for almost a decade. His first passive house experience was with Team Illinois in the US Department of Energy's Solar Decathlon Competition in 2009, where the team took Second Place overall. Abendroth is a member of the PHIUS Technical Committee and a trainer for the PHIUS CPHC Training Program, the PHIUS+ Rater Program, and advanced tutorials on topics related to passive building construction.

Abendroth also serves as the Principal of Passive Energy Designs LLC, a St. Louis, Missouri-based consulting firm specializing in achieving built high-performance and low-energy buildings that meet the passive house standard. He holds a Master of Architecture and a Bachelor of Science in Architectural Studies from the University of Illinois at Urbana-Champaign. Currently, Ryan is a lecturer at the Sam Fox School of Design and Visual Arts at Washington University in St. Louis where he teaches both graduate and undergraduate courses focused on the impacts of climate, site, energy, detailing, and building information modeling (BIM) on the built environment. Previously he taught at the Rhode Island School of Design as both a Visiting Lecturer and Critic and has acted as a passive house consultant for Kansas University’s 5th year design-build program, Studio 804.

Florian Antretter

Group Manager, Hygrothermal Building Analysis at Fraunhofer IBP

Florian Antretter leads the group for Hygrothermal Building Analysis at Fraunhofer IBP. The group examines the hygrothermal performance and interaction of the building envelope and systems with the enclosed space. The achieved insight is used to develop and apply a hygrothermal whole building simulation tool, the WUFI® Passive software, which allows a detailed analysis with regards to energy use, indoor environment and the hygrothermal conditions in the building envelope. Antretter first gained experience on building sites as a certified craftsman. He expanded his experience in material, component and whole building measurements in the laboratory and in the field through statistical data assessment at Fraunhofer IBP and Oak Ridge National Laboratory. He is an expert in hygrothermal building component and whole building simulation as well as in application of computational fluid dynamics software. His involvement in North American, Asian, and European projects enables him to conduct research and develop solutions in an international environment. Antretter has served as a lecturer in the Civil Engineering program at the University of Applied Sciences in Munich, Germany since 2010, and serves on the PHIUS Technical Committee. He has published more than 20 scientific articles in international journals and conference proceedings.

Prudence Ferreira

Partner, Passiv Science

Prudence Ferreira is a Partner in Passiv Science, a consulting partnership focused on large scale multifamily, commercial, and institutional passive building projects. She heads the firm’s energy modeling team and has unique expertise and experience with WUFI® Passive. Her credentials include LEED AP BD+C, LEED for Homes Rater, GreenPoint Rater Certified Title 24 Energy Analyst, Hygrothermic Analyst, and Certified Passive House Consultant (CPHC®). She is a licensed trainer, core curriculum developer, and exam author for Passive House Institute US (PHIUS), and teaches the CPHC® training program and advanced passive house technical workshops around the US. She helped author the CPHC Exam, helped train over 500 CPHCs, and is a core contributor to CPHC training curriculum. Ferreira also teaches Hygrothermal Analysis around the US as a certified instructor for the Fraunhofer Institute for Building Physics and Oakridge National Lab’s WUFI-ORNL program. She plays a key role in the partnership between the Fraunhofer Institute for Building Physics and PHIUS in developing, beta testing, and field verifying a new energy and hygrothermal analysis design tool specifically for passive, low and zero energy building design and verification.

Ferreira currently serves on the PHIUS Board of Directors, where she previously served as President, and as a member of the PHIUS Technical Committee. She also interfaces with USGBC national technical staff on the LEED for Homes and PHIUS+ Standard integration effort and inputs significantly continuing education program development. Ferreira is a founding member of the PHIUS Technical Committee and has consulted on 30+ passive house projects across 7 different climate zones.

Stuart Fix

Principal, ReNü Engineering Inc.

Stuart Fix is the Principal of ReNü Engineering Inc. He is a professional mechanical engineer (University of Alberta 2006) with a master’s degree in building science (Ryerson University 2010) and holds certification as a Passive House Designer in both Germany and North America. Stuart is a founder of Passive Buildings Canada and has been one of Canada's Passive House pioneers. Stuart has a background in machine design and project management, and has been active in high performance building design since 2008, having worked on over 750 projects. He focuses on leading edge mechanical design, building electrification, and is fascinated with the integration of mechanical and envelope systems in the pursuit of cost effective energy efficiency. Stuart is an accomplished technical designer and an experienced contributor to inter-disciplinary groups in a global setting. Stuart has served on the PHIUS technical committee since 2011.

Achilles Karagiozis

Director of Building Science, Owens Corning

Achilles Karagiozis is Director of Building Science at Owens Corning, where he is charged with accelerating energy efficiency improvements in the built environment. Prior to joining Owens Corning, Karagiozis worked at the prestigious Oak Ridge National Laboratory, where he was a distinguished research engineer and hygrothermal project manager. He was instrumental in the launch of a number of innovative construction material and system products, as well as the development of design guidelines, software tools and code changes. Karagiozis received his Ph.D. from the University of Waterloo in Ontario, Canada, with work at the von Karman Institute in Fluid Dynamics in Saint-Genese Rode, Belgium. He received his M.Sc.E. and B.Sc.E. from the University of New Brunswick in New Brunswick, Canada.

Katrin Klingenberg

Co-Founder & Executive Director, Passive House Institute US (PHIUS)

Katrin Klingenberg designed and built the very first home in the United States built to the passive building energy standard. Her experience led her to co-found e-cological Construction Laboratory (e-colab) with builder Mike Kernagis in 2003 as a non-profit affordable housing developer in Urbana, Illinois to further investigate the feasibility of applying passive building principles in the United States. As interest in passive building grew in North America, Klingenberg and Kernagis oversaw the expansion of e-colab into Passive House Institute US (PHIUS) in 2007. PHIUS is now the leading passive building standard setting, research and information provider, training, and certification institute in North America.

Klingenberg has since designed and consulted on numerous passive building projects across North America’s varied climate zones. In her role as Executive Director of PHIUS she directs the technical and research programs of the organization. In addition to her executive role, she is also the lead instructor and director of curriculum development for the PHIUS Certified Passive House Consultant (CPHC®) Training program. Klingenberg earned the German equivalent of a B.S. in Architecture at the Technische Universität in Berlin, Germany, earned an M.S. in Architecture from Ball State University, and is a licensed architect in Germany.

Tony Lisanti


Tony, lives in Rockland county, NY a suburb just north of New York city. He has an Associate’s Degree from S.U.N.Y. Alfred in Internal Combustion Engine Engineering Technology, a Bachelor’s of Science Degree in Mechanical Engineering from the Rochester Institute of Technology, and a Master’s of Science Degree in Organizational Leadership from Mercy College.

He has been employed as a Mechanical Engineer with a consulting engineering firm in Rye, NY; as a Maintenance Specialist and Account Executive with Con Edison, as Director of Energy Sales and Service for Robison Energy in Westchester County, NY and currently as Managing Director at Integral Building & Design, Inc.

In 2003 he became a Certified Home Energy Rater and began assisting homeowners, builders, developers, and contractors in meeting current Energy Code, Energy Star Homes and many other high performance building requirements. He has over 2000 dwelling units certified for the EPA Energy Star Program, and completed many other Ratings for code compliance, EPA Indoor airPLUS, DOE ZERH and PHIUS+. He has worked with several municipalities in NY State including the NY Dept. of State in developing higher energy code standards.

Other qualifications include Certified Energy Manager (C.E.M.) Passive House Rater, Verifier and Passive House Consultant, D.O.E. Zero Energy Home Verifier, RESNET Quality Assurance Designee, RESNET Rater Trainer, Certified Green Professional by the National Association of Home Builders and numerous certifications from the Building Performance Institute.

He serves on the Board of Directors of the Passive House Alliance - Hudson Valley Chapter, participates on several RESNET working groups, the Rockland Business Association Green and Commercial Real Estate and Development Councils, Timberline Condominium Home Owners Association and previously was Vice-President of the North East Home Energy Rating System Alliance.

Chris McTaggart

PHIUS+ Rater Program Manager, Building Energy Resources (BER)

Chris McTaggart is the QA/QC manager in support of the PHIUS+ Rater program and leads the PHIUS+ Rater and PHIUS+ Verifier training programs of Passive House Institute US (PHIUS). He also serves on the PHIUS Technical Committee. McTaggart is Co-Principal at Building Efficiency Resources (BER), a national third-party RESNET QA Provider working with independent rating companies throughout the United States. McTaggart brings a background rich in research, analysis and logic developed both through his professional experience and formal education at Michigan State University.

Russell Richman

Professor, Department of Architectural Science, Ryerson University

Dr. Russell Richman is a Professor in the Building Science Group within the Department of Architectural Science in the Faculty of Engineering & Architectural Science at Ryerson University in Toronto. He has conducted research in building science and sustainable buildings since 1998. Dr. Richman is the Director of the Graduate Program in Building Science in the Department of Architectural Science. This program, unique in North America, combines the fundamentals of building science with the broad mandate of sustainable engineering and building design. Dr. Richman also serves on the Technical Committee of Passive House Institute US (PHIUS).

Colin Schless

Vice President, Thornton Tomasetti

Colin Schless, CPHC, LEED AP BD+C, has more than 11 years of experience in green building consultancy and leads Thornton Tomasetti Engineering’s East Region building analytics group. He specializes in commercial building energy modeling, daylight analysis, climate analysis, simulation tool development, and data visualization. In addition, Schless manages Thornton Tomasetti’s efforts with Zero Carbon and Passive House projects. Schless received his Master of Architecture in 2010 from the University of Oregon, where he worked as a Research Fellow at the Energy Studies in Buildings Laboratory. His project experience ranges from a 340,000 sf museum in Riyadh Saudi Arabia, to Zero-Carbon Life Science buildings in the City of Boston, to 120 mixed use buildings owned and operated by Sweden’s largest real estate property holder, Vasakronan. Colin was the CPHC on Village Centre in Brewer, Maine, a 48-unit affordable housing project that won PHIUS’ 2016 Passive Projects Competition awards for the Best Multifamily project and Best Affordable project of the year.

John Semmelhack

Owner, Think Little

John Semmelhack is the owner of Think Little, a building science consulting firm based in Charlottesville, Virginia, specializing in building enclosure and mechanical system design for single-family and multi-family
Passive House and net-zero energy homes in the mid-Atlantic.

Since 2007, Think Little has provided consulting, testing and inspection services for over 2,500 multi-family and single-family housing units, including several firsts – the first certified Passive House residence in Virginia as well as some of the first EarthCraft certified net-zero homes.

John is a certified Home Energy Rating System (HERS) rater and an EarthCraft Technical Advisor. John is also a CPHC® (Certified Passive House Consultant), is a member of the Passive House Institute U.S. (PHIUS) Technical Committee, and is a PHIUS Trainer for the CPHC training program.

Galen Staengl

Principal LEED ® AP BD + C, CPHC

Galen Staengl has more than 20 years of experience designing cutting-edge energy- efficient mechanical systems for green building projects and industrial facilities. Throughout his career, Galen has worked to bring energy-efficient and sustainable principles into his designs for award-winning schools, institutional buildings, multi- family residential projects, and office buildings. As President of Staengl Engineering, Galen has provided design and energy analysis for buildings certified as LEED Platinum and Gold, Passive House, Net Zero energy, Net Positive energy, and Living Building Challenge.

As a leader in low-energy building system design, Galen regularly presents and moderates at national and regional green building conferences. He is also involved in advancing the technical and regulatory aspects of green building design in the U.S.; he is currently a member of the national Technical Committee of Passive House Institute U.S., and a voting member of ASHRAE Standard Project Committee 227P, Passive Building Design Standard.

Skylar Swinford

Principal, Energy Systems Consultants

Skylar Swinford is the Principal of Energy Systems Consultants (ESCO), an Idaho-based building energy and enclosure consulting firm. Swinford graduated with a degree in Environmental Science from Willamette University in 2007 and has worked in the high performance building industry since. He is a Certified Passive House Consultant (CPHC®), PHIUS+ Rater, and a BPI-certified Building Analyst and Envelope Professional. He has consulted on hundreds of residential and commercial building projects in the Northwest and across North America. This ranges from his work on many Net-Zero Energy and Certified Passive House projects, to the forensic evaluation of failed buildings.

Lisa White

Associate Director

Lisa White serves as the Associate Director for the Passive House Institute US (PHIUS) and has been with PHIUS since 2012. Prior to this role, she led the certification review team. She is an instructor for Certified Passive House Consultant (CPHC®) and WUFI Passive software training. White holds a degree in Environmental Sustainability with a minor in Architecture from the University of Illinois at Urbana-Champaign, and a Master’s in Energy Engineering from the University of Illinois at Chicago.

White works on certification, training, and WUFI Passive development and is a member of PHIUS’ technical committee. She also provides consulting services on static and dynamic energy modeling in WUFI Passive, THERM modeling, and project planning specific to passive building principles. White has presented at numerous conferences and events, including Greenbuild, ASHRAE, PHIUS Annual North American Passive House Conferences, the Affordable Comfort Institute national conference, and Facades+.

Graham S. Wright

Senior Scientist & Chair of the PHIUS Technical Committee, Passive House Institute US (PHIUS)

Graham Wright earned his Ph.D. in Electrical Engineering at the University of Illinois in 1993. After a 10 year career in the printing industry, he refocused his work on energy efficiency and renewable energy in 2007. He first volunteered with Americorps VISTA and then trained as a Passive House Consultant in 2008. He worked as an independent consultant, became licensed as an instructor for the PHIUS Certified Consultant Training in 2011 and began working for PHIUS in 2012 as a building scientist. He leads standards, certification and energy modeling protocol development at PHIUS, sets the research agenda for the Technical Committee and co-authored the PHIUS+2015 Passive Building Standard developed in 2015 in cooperation with Building Science Corporation under a Department of Energy grant. It is the only passive building standard of its kind in the world that is based on bioclimatic design guidelines and energy targets. Graham also developes and manages PHIUS's product certification programs.

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