Tenant area with prescribed HVAC system in a CS project

Dear Expert, In our CS project the owner wants to limit the tenants to a specific HVAC system with under floor air distribution. The MEP engineers have considered a bulk cooling load for the tenant spaces based on occupancy and thermal performance of the envelope. In the energy model, the design case parameters are considered the same as the base case per standard requirement for Core and shell buildings. The owner is keen to know whether it is possible to show energy savings in energy model for the tenant areas since he is specifying an efficient HVAC system in these areas? Secondly in the energy model, is it possible to reduce the volume of the air being cooled because of the UFAD? our energy modeler is unable to find a solution to this issue being raised by the owner. Your opinion on the above would be highly appreciated. Thanks and regards Farhana