The primary purpose of an hvac system should be to create an energy-efficient, healthy, comfortable environment that appears neutral to most inhabitants — neither too hot nor too cold. Its function is to raise or lower the operative temperature and control indoor air quality using a combination of heat transfer and quality control mediums.
Designing an hvac system to heat and cool a space is quite different than designing a project for heating and cooling comfort. True human gratification cannot be accomplished without addressing radiant losses or gains, which means an hvac system designed for comfort should incorporate some form of radiant.