Lighting steps vs on/off

Hello everyone, I am currently working on a LEED for CI v4 project. It consists on a small office space (1100 sf ) that is located within a high efficiency building, pursuing the LEED for CS v3 certification. The base building has already provided the lighting fixtures for the project. These are T5 fluorescent with a standard consumption of 14 W each, not dimmable. The office is well illuminated with natural lighting, therefore its requirement for electrical lighting is almost none, so my question here is, is it necessary for my client to buy either dimmable ballasts or LED fixtures that allow the required 0, 30-70%, 100% steps? or can we document compliance by stating that the project barely uses electricity to fullfill the necessity for lighting? It does not make much sense to my client to replace all the existing luminaries just to change the fact that they do not have the middle step between 30 and 70%, especially since the project is already achieving a 40% lighting use reduction and because of their little necessity for electrical aided lighting. Can someone help me, please? Thanks!