Future space

In case of project with an area which is already designed but yet built (less than 40% of gross project area), can we use "owner's commitment" instead of "leasing agreement" to state all the design paramenters to be used in energy modelling (for avoiding using baseline data)? This space will not be leased but reserved for the future expansion of the owner. Actually, Owner's commitment will be very similar to leasing agreement. The docoment name will clarify that this document is for owner not the tanent.