Context - Minimum thermal performance standards for residential building envelopes have been increasing in many countries for several decades, addressing concerns about occupant comfort, operational costs and greenhouse gas emissions. Simulation tools play a role in assessing the space heating/cooling load of new buildings and for evaluating options for systematic retrofitting of exisiting dwellings. The purpose of this study was to examine the role and limitations of simulation in informing potential retrofit activities for an aged care facility. Methodology - The study utilised a 110 apartment Aged Care facility as a case study. Two typical apartments from this case study were selected for indepth study. A simulation tool (BersPro 4.1) utilised for regulatory purposes in Australia for new construction, was utilised to simulate existing building thermal performance and expected performance of three retrofit actions. Results – The thermal performance of the existing buildings meet regulatory requirements at the time of construction (pre 2006) but are 70% higher than current regulations. Enhanced air movement, through the installation of ceiling fans, showed the largest reduction in space heating/cooling load (52.5%), followed by ceiling insulation (22.6%) and double glazing (4.3%). Key Findings – The simulations identified differences in the heating/cooling loads of sleeping and living spaces within the apartments. The benefits of the proposed retrofit options, however, are questionable because of practical limitations of the existing building and the mismatch between these occupants and occupancy assumptions made in the simulation tool. Originality - This paper applies a simulation tool to an examination of retrofit options for existing senior housing. It reveals limitations in relying on simulation tools for this purpose unless other issues, such as the uniqueness of this particular demographic, are equally considered.