No front room, that should be closed stairwell. Closed stairwell to meet the requirements of natural ventilation and lighting. Therefore, according to the description, the ground can not do mechanical pressurization.

But the underground does not meet, so the underground must do pressurized air supply.

As for whether to be placed on the roof or basement, according to the building form, if possible, try to be placed on the roof. Reason: you can eliminate the basement fan room, outdoor air inlet well, air inlet louvers, but increased from the roof to the basement of the pressurized air well.

The above is based on national norms, sometimes there are some more detailed requirements within the provinces, depending on the location of the project.