Be certain you can make alterations to the space after the initial move-in, typically with the building owner's approval. Your lease should specifically state that the credit union is not responsible to pay for alterations within your space to meet changing code requirements, unless your alterations caused a violation. Try to negotiate a lease without an escalation clause. Tenants with leases of 10,000 square feet and less often find that electrical, water, sewer, garbage and HVAC costs are included in their lease payment. Larger tenants typically pay their own electrical bill.
Most leases require the tenant to pay a prorated share of operating costs.
Make sure those costs are specified. Your credit union should not be responsible for the misconduct or negligence of the owner's company or its employees. The building owner carries liability and property damage insurance for the building shell, core operating systems and common areas. Make sure you get a copy of the landlord's insurance policy. Destruction of property.