We have developed an innovative lighting system prototype for a patient room application that integrates a multi-channel luminaire platform into indoor general area luminaires. This system is energy efficient, spectrally tunable, and supports the visual and nonvisual needs of occupants. We evaluated the performance of two separate multichannel platforms in different luminaire types, using a unique color-processing algorithm. The LED modeling and simulations enabled optimization of spectral power distributions, color, light output, and efficacy. This paper discusses the complicated results of SPDs developed for the patient room application, especially how they are effective for positively supporting the human visual and non-visual (circadian) systems. Additionally, application measurements demonstrate the large impact of the application space on the resulting SPD of a luminaire, calling into question the feasibility of using traditional field measurements to validate luminaire performance.
A field study was conducted at three clothing stores to validate previous laboratory findings indicating that colored
LEDs used as background display lighting could: 1) lower the power demand of accent lighting by up to 50 percent; and
2) provide greater attention capture and visual appeal than current lighting practice.
Blue LEDs provided a colored background for window mannequins by illuminating white backdrops. Eliminating
fluorescent general lighting and reducing the number and wattage of halogen accent lamps in the display windows
reduced the lighting power demand by up to 50 percent. During an eight-week period, more than 700 shoppers rated the
attractiveness, eye-catching ability, comfort, and visibility of four different lighting conditions. The results of this field
study showed that by introducing color contrast between the displayed objects and the background, the power demand of
the accent lighting could be reduced by up to 50 percent without sacrificing visual appeal, visibility, ability to capture the
attention of shoppers, and the ability to see the colors of the objects on display. Furthermore, the sales of the products on
display were not affected by the 50 percent reduction in lighting.
Great strides have recently been made in the development of white light emitting diodes (LEDs), although perceptible variations remain in the color and brightness of nominally identical products. The objective of this study was to examine color and brightness discriminability between different white LEDs when used as illuminants of colored and achromatic objects. A method of successive comparisons was used to assess discriminability rather than the more typical simultaneous (side-by-side) comparisons using a "same-different" response protocol. Three-dimensional "tolerance zones" were developed based upon discriminability in a chromaticity (u', v') and luminance when illuminating the colored and achromatic objects. These "tolerance zones" could be used to establish specification tolerances for different lighting applications.