An integrated skylight luminaire: Combining daylight and electric luminaires for energy efficiency

Russell P. Leslie and Jennifer A. Brons, Lighting Research Center, Rensselaer Polytechnic Institute, USA

Keywords

daylight, skylight, photosensor, self-commissioning, wireless commissioning, hand-held commissioning device, high-bay, warehouse, retail, fluorescent, dimming, integrated skylight luminaire, ISL

Abstract

Skylights have the potential to save substantial energy while improving the visual environment within large, high-ceiling buildings, such as factories, warehouses, supermarkets, and “big-box” retail stores. To capture these energy savings, the electric lights must be appropriately dimmed or switched when daylight is sufficient. To improve the visual environment, sunlight distribution must be controlled. This paper describes the development, construction, and evaluation of an integrated skylight/luminaire (ISL) designed to provide ambient lighting for “high-bay” buildings, replacing traditional high intensity discharge lighting systems. A single product specification defines the skylight, electric lighting system, and the controls system.

The ISL works under sunny and overcast conditions, is composed of readily available hardware, automatically captures energy savings, controls glare, and is easy to install and maintain. The control system is capable of dimming and switching. The photosensor control algorithm is easily set by a hand-held wireless commissioning device.

Several prototypes were designed using various electric lighting components, glazing options, concentrators, and diffusers. A team of designers, optical designers, human factors specialists, and engineers evaluated these prototypes for cost, glare control, transmittance under clear and overcast skies, illuminance, uniformity, and whole building energy use in northeastern United States climates. The team used design software, physical models, and whole-building energy simulation programs. The selected prototype was built in full scale and installed in the Lighting Research Center (LRC) laboratory for evaluation and demonstration. A roundtable of manufacturers, energy-efficiency program managers, architects, engineers, and designers reviewed the installation.

The results of the energy simulations, illuminance calculations, prototype evaluation, and human factor analysis are described.