The building energy estimated by a simulation model changes when new values are assigned to input variables. In a recent study, building energy models were tested for sensitivity to changes in 25 input variables. Certain energy changes were more significant than others, suggesting that selected inputs should be given particular attention during modelling. The study focused on two buildings in the Pacific Northwest. One building was representative of small retail buildings and the other was an example of large office buildings. The sensitivity analysis was repeated for each of the two buildings using five different software packages, resulting in 10 building energy models. The degree of sensitivity noted for any one measure (input change) differed between the two building types. In general, the models were comparatively less sensitive to measures affecting the building envelope and lighting and more sensitive to measures involving occupancy, weather, air supply, systems, and plant.KEYWORDS: buildings, calculating, energy consumption, testing, USA, offices, shops, computer programs, comparing, energy conservation, accuracy