Net zero energy buildings (NZEB) are becoming more common, and as new energy saving designs and technologies become available, the ability to estimate overall energy use and understand the impact on operation of building appliances will become important. This paper outlines simulation results of performance improvements achieved by modifying various components (glazing, lighting, thermal comfort settings) of two tertiary education NZEBs and a typical modern commercial building. The DesignBuilder models’ thermal performance and energy consumption were validated using real data from case study buildings. The work shows validating models of smaller, less conven-tional, buildings is more difficult than for larger conventional ones. Performance of NZEBs was benchmarked against the typical commercial building, and subsequently the impact of alterations to overall energy savings established. Results illustrate that NZEBs appear more sensitive to design changes. The work indicates significant savings are achievable in NZEBs and conventional buildings if suitable glazing is selected, lighting controlled according to daylight, or comfort band settings adjusted appropriately. Poten-tial savings are quantified using models developed and validated in simulation.