This 45-page 1997 report by Danny Parker et. al. of the Florida Solar Energy Center describes an $8,500 retrofit of an all-electric home in which measured energy was reduced by 40-45%.
This case study showcases a multifamily renovation, including technical details and actual versus modeled energy use. This is a must-read introduction to Passive House building renovations.
Betsy Pettit’s exciting results are chronicled here under Affordable Comfort Home Performance Conference, April 2007.