EQc7.1 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. Earning this credit also sets the stage for you to earn EQc7.2: Thermal Comfort—Verification. 
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.

Natural ventilation and certain occupancies make it tricky


Meeting this credit in naturally ventilated spaces is tricky, because it’s hard to ensure that thermal conditions remain within the requisite range. It’s really only possible in a few specific climatic regions with especially temperate conditions.
 Certain spaces, such as greenhouses, gymnasiums, warehouses or manufacturing facilities often operate outside of the ranges defined by ASHRAE-55, which can put the project in conflict with designing either mechanical and passive systems that meet the credit requirements. If you have these spaces in your project, check with the USGBC and review past CIRs to determine  whether you can earn the credit through an alternative compliance path. 
Regardless of the project type, considering target thermal comfort conditions—and designing to meet those conditions—early in the process is very helpful.