This paper describes the results of a project that studied the reduction of purchased energy of existing houses by 40% with the cost of the retrofit measures being acceptable to the homeowners. The five houses examined in this project are located in Saskatoon, Saskatchewan, Canada. The houses varied in age, being built between 1911 and 1986, and contained a wide variety of styles, occupancies, etc. After one year of post-retrofit monitoring, the total energy consumption (electricity and natural gas) of the houses was reduced by up to 39.6%.