Building Simulation for a non AC Facility

We are working in a Garment Factory project in Sri Lanka where the facility is to be LEED certified. Whole building will be put up as a non air conditioned facility. mechanical ventilation systems would be installed to provide fresh air to the building. since the facility is located in an area with a tropical climate occupants are assured to have required thermal comfort. But the problem we are having is since ASHRAE 90.1 is developed for Air conditioned facilities is it possible for us to claim energy savings for this particula facility through an energy simulation based on ASHRAE 90.1 standards. We will not claim any credits for air conditioning and only hope to claim credits for savings on artificial lighting. will this procedure be accepted? if the above is not possible should we go for a manual calculation to prove energy savings? but the LEED guideline says manual calculations are accepted only when the simulation can not be used to reflect the actual scenario. how would this clause affect here? please advice on the best way forward. thanks in advance.