In OpenStudio on the "Results Summary" tab, you can select "EnergyPlus Results" from the Reports dropdown menu in the top left. The default is in SI units. If they are in IP units, that means you probably have an EnergyPlus measure in your OpenStudio measures tab to set the output reporting to IP units. Removing that measure will make EnergyPlus report in SI units.

The default OpenStudio Results report that you see in the OpenStudio results tab is in IP units by default. Someone else can comment here if there is a way to report it in SI units instead. The default OpenStudio Results electricity section does report in kWh.