A lighting and energy conservation system for low temperature applications includes LEDs as a light source. The LEDs are provided in a modular LED light fixture. The fixture includes a frame supporting a reflector having a plurality of elongated channels. Mounting strips are removably installed in each of the elongated channels, and LEDs are mounted on each of the mounting strips. Interchangeable lenses are provided over the LEDs and are removably coupled to the mounting strip by a quick-connect device. A separate multi-position power control device is associated with each of the mounting strips, so that a total light output intensity and profile of the fixture can be individually customized by any one or more of: interchanging lenses on the LEDs, interchanging mounting strips within the elongated channels, and selectively adjusting the multi-position power control device for each of the mounting strips.