You cannot define spaces in Revit Architecture, however you can define rooms then ensure that the volume computation is set on. Now you have a 'space' that is just not as clever as a space. your MEP engineer will now be a big fan of you as they can use the rooms to define the space names and numbers...
try the export to gbXML after creating the rooms and you will see that the rooms are defining volume, in Ecotect these will become zones, likewise in GBS (not sure what GBS calls them).
one thing to ensure is that you define every interior mass in the building (chases/sliver spaces), and that includes in the vertical sense.
Drew