Abstract: Provided herein is a high intensity discharge light source having a thermally insulative and optically transparent sleeve for maintaining or enhancing a spectral performance parameter. The configuration of the sleeve provides an insulative volume that allows an elevated steady state operating temperature to be reached, even when the light source is cooled. The sleeve is also configured to withstand a bulb failure event, thereby protecting the surrounding environment from falling debris. Also provided herein are methods for dissipating heat from the light source without adversely affecting the bulb operating temperature or the enhanced spectral performance parameter.

Abstract: Provided herein are optical reflectors having a plurality of specially designed reflective surfaces and geometrical arrangement to provide improved illumination of a target area. Also provided are related methods for growing plants with the optical reflectors described herein. The reflective surfaces provide substantially normally aligned light over the entire target area, thereby minimizing shading issues of conventional optical reflectors. Also disclosed herein are efficient cooling by air and/or fluid that can substantially reduce cooling requirements by conventional air conditioning with attendant power savings.