ABSTRACT: This paper reports the testing of appropriate design standards to optimize energy performance in the pursuit of building retrofits. The impact of whole-building "best" and "normal" practice standards are predicted and evaluated using as a case study a forty-year-old heavy coredependent deep-plan twenty-three storey office building in Brisbane. Predictive modelling used DesignBuilder simulation software. A Forward Simulation Model (FSM) and Data-Driven Simulation Models (DDSM) contributed to the evaluation of "normal" and "best" practice standards. With higher thermal resistance in the built fabric the PassivHaus Model (PHM) -a "best" practice standarddemonstrated a maximum energy saving of 9.5%. Findings suggest that retrofitting for energy saving in internal-load dominated office buildings requires strategies to control internal loads. The wholebuilding energy standards with efficient operational profiles promoted 46% of energy savings, showing systematic appraisal and prediction to derive case-specific design solutions in satisfying the regulatory measures for future commercial buildings in Australia
