A floor system that combines a radiant in-floor heating system with a structural floor system using heated air as an energy source and sealed floor panels as radiant bodies. Hot air circulates internally throughout the sealed floor system heating metal joists, a radiant metal sheet, the structural sub-floor, the interior floor surface and objects within the living space above. Hot air is directed from a furnace through a duct and into arranged airflow pathways within the sealed floor system before returning to the furnace via a duct for reheating. The arranged airflow pathways are created by parallel metal joists, the structural sub-floor on the top of the metal joists, an enclosed board at the bottom of the metal joists and wood rim boards. The sealed floor system is prefabricated as modular panels and delivered to the construction site. There are three types of panels: (i) a utility floor panel for connecting the ducts to and from the furnace, (ii) a standard floor panel for mass production and (iii) an end floor panel for special layout requirements.