Unrenovated space HVAC system and lighting unknown

LEED-NC, while somewhat accommodating for major renovations, does not allow exemption of existing systems from the energy efficiency credit/prerequisite. If the existing systems are within (or serve areas within) the LEED project boundary, they must be included in the model as constructed. This is the main reason LEED-NC only applies to MAJOR renovations, typically including much of the envelope and all of the HVAC in the scope. There is likely some additional nuance to this (others in this forum may chime in), although from a big picture perspective, there is no free pass for existing equipment in the energy model. If a significant portion of the HVAC is going to be maintained, it might be better to consider LEED-CI or LEED-EB as a better fit for the project. Another option would be to use LEED-NC on just the renovated portion of the building, although this comes with its own set of considerations, and isn't appropriate for all situations.

Existing HVAC and lighting that remains within the project must be modeled identically in both models. If you don't know what is there you will need to find out.