For too long, the green residential buildings conversation has focused on new construction. Existing homes deserve their day in the sun. This occupied retrofit case study illustrates how homeowners transformed a 100-year old home in an urban setting from a HERS Index 173 resource hog into a svelte HERS 59 LEED v4 Platinum residence with emphasis on improved indoor air quality. Maureen Mahle presents a case study of the retrofit of her own 1915 home, in the spirit of learning from our mistakes. She’ll highlight the tough choices when energy, indoor air quality, existing conditions and budget constraints intersect; the easiest and toughest credits for rehabs under LEED v4; building performance test results throughout renovation; and 5 years of utility data pegged to each major upgrade.