This paper describes the development and implementation of a comprehensive methodology to select and implement energy efficiency upgrades to the homes of low-income, older (>60 years) Australians. This work was conducted as part of a project entitled, 'Energy Efficiency in the 3rd Age (EE3A)", which targeted lowincome older residents in the Illawarra Region of NSW, Australia, and was funded by an Australian Federal Government 'Low Income Energy Efficiency Program (LIEEP)' grant for AUD2.3M. The project included a social marketing and behaviour change component engaging ~650 households, and a retrofit program for a subset of ~183 of these homes. Households included those from the general community (home owners) and from the aged-care sector, i.e. those living in Independent Living Units (ILUs). This paper describes the development of a unique Building Characterisation Tool to facilitate the rapid recording of up to 1,500 features of each building, which was implemented on laptops/tablets and captured information on the ways in which the occupants used their homes. A retrofit prioritisation process was also developed whereby a detailed assessment of each home was made from the Building Characterisation data. Results are also presented on the overall characteristics of the dwellings occupied by this vulnerable section of the population and preliminary results on impacts on thermal comfort, etc.