An LED-based lighting system includes a housing forming one or more apertures, a PCB having conductors on its front-side, and one or more LEDs mounted with the conductors. The PCB mounts with the conductors proximate to a top surface of the housing such that the LEDs emit light through the apertures, and heat generated by the one or more LEDs primarily dissipates through the conductors to the housing. A retrofit apparatus for a light fixture includes a PCB having conductors on its front-side thereof, and one or more LEDs mounted with the conductors. The PCB mounts with the conductors proximate to a surface of a mounting bracket that is configured for mounting to the light fixture, such that when the bracket mounts to the light fixture, heat generated by the one or more LEDs primarily dissipates through the conductors and the structural element to the light fixture.