Abstract: A linear panel unit for use on walls or ceilings capable of providing radiant heating and/or cooling. The panels have an external panel shell, which itself can be used as a passive panel, an extruded aluminum radiator panel resting in the shell with outward side in contact with the shell and an inward side in contact with a copper tube capable of containing fluids of varying temperature. Clips between bilateral troughs in the sidewall of the panel shell and the inward side of the radiator panel secure contact between rediator panel and the shell. The copper tube is grasped by projecting channel walls in the inward side of the radiator panel which also are tapered to facilitate positioning of the clips and a groove near the intersection with the radiator panel to secure placement of the clip. A panel unit wall or ceiling is created by interspersing radiant linear panels with identically appearing passive panel shells, the copper tubes of the active radiant panel units communicating with one another.