This paper presents the results of a study carried out in the US to estimate energy savings data obtained from efficiency upgrades of key building components using parametric energy simulations. The method used is aligned with the ASTM Standard Guide for Building Energy Performance and Improvement Evaluation in the Assessment of Property Condition. The percentage savings metrics can be applied to the actual energy use of a building to estimate the savings for a given building. Energy efficiency metrics for office and retail buildings – pre 1980/post 1980/post 2004 – are illustrated in graphs for different climate zones in the US.