This credit requires that HVAC designs meet the requirements of ASHRAE Standard 55-2004, which deals with thermal comfort of building occupants. Specifically, ASHRAE 55 requires project teams to address air temperature, radiant temperature, humidity, and air speed.

In most cases, designing a system that complies with ASHRAE-55 is standard practice and documentation is the only LEED-specific requirement for achieving the credit, so it should cost very little to earn. 

Base building mechanical systems have to allow for the tenant fit-out to meet the requirements of ASHRAE-55. If all the mechanical systems are relegated to tenant fit-out, LEED-CS projects are not eligible. Consider this early in the planning phase of a core-and-shell project.