Participants will learn about basic passive house principles and overcoming constructability, economic and policy related challenges related to working in vintage buildings through the exploration of the Yannell PHIUS case study, a 120-year-old residential structure in Chicago that was the first PHIUS Retrofit in a 14-state region in the Midwest. Over 98% of our buildings are not new – they already exist. In order to meet the challenge of designing for resilience in the face of climate change, existing buildings of increasingly vintage or even historic nature are being faced with this existential crisis: how to not only electrify to prepare for a carbon-free economy, but to prepare existing envelopes with today and tomorrow’s technology in order to support energy and resource efficiency as they become more scarce. The case study of the award-winning Yannell PHIUS project, the first of its kind in the Midwest, will tackle this issue through the lens of retrofitting a 120-year old farmhouse to passive house performance standards (PHIUS). While vintage but not specifically historic, the challenges faced and goals achieved by the project are easily extrapolated to historic structures: how to create air barriers in existing buildings above and below grade, how to promote selection of efficient building systems and infrastructure to support electrification and energy savings, creative ways to adopt passive house principals that are economically feasible and market ready.