introduction luminaire selection criteria results

INTRODUCTION

METHODOLOGY

• This paper describes the methodology and results of a study which examined the impact of luminaire optical control and lamp configurations on lighting energy consumption in office spaces.

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• Commercial 2’x2’ troffer luminaires for direct lighting in office applications were analyzed through manufacturer published photometric data using a software tool created specifically for this study. •

Results derived from the analysis were compiled and categorized to identify performance trends among luminaires.

RESULTS

Ceiling (Reflectance: 80%)

Basis for Performance Comparison: Lighting Power Density(LPD) Walls Number of luminaires analyzed: 505 (Reflectance: 50%) 10’ Number of luminaire manufacturers considered: 23 The Lumen Method was employed for design calculations. 2.5’ Floor Design criteria: (Reflectance: 20%) 25’ • Required Illuminance: 300 lux (average) at work-plane 15’ • Room Details: See Figure 3. • Representative ballast factors and lumen depreciation Figure 3 : Dimensions and details of the room values were applied.

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COMMERCIAL TROFFERS: A PERFORMANCE SURVEY Photometric Tests to Study Performance Trends among Troffer-Style Luminaires for Office Applications

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Sarith Subramaniam, Richard G. Mistrick, Ph.D. The Pennsylvania State University

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4 SOFTWARE PROCESS FLOW

LUMINAIRE SELECTION CRITERIA OPTICS

LAMPS HYBRID LUMINAIRES Optical system is comprised of a high efficiency refractor and reflector system. Output is volumetrically distributed. Such luminaires are usually referred to as “High Efficiency” in catalog data by manufacturers

RECESSED DIRECT-INDIRECT LUMINAIRES Recessed direct-indirect luminaires are characterized by output which is a combination of directional and diffusely reflected light. The diffuse component of output is higher when compared to the hybrid luminaires. LENSED LUMINAIRES Lensed luminaires employ a polycarbonate, acrylic, or glass-based refractor as their primary optical system. Luminaires which employ a combination of lensed refractors and parabolic louvers were also included in this category.

LOUVERED LUMINAIRES Luminaires that employ standard metallic or acrylic louver-based optical systems were included in this category.

SORT

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Luminaires are categorized according to Optics and lamp-type IES files are stored in different folders on basis of their category. Folder Structure : Root Folder Optics Lamp type The software tool is pointed to the root folder

LED

CONCLUSIONS CFL

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CALCULATE

LOOP

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Software lists all IES files present in the selected folder. Luminaire photometric data is extracted from the IES file Quantity of luminaires is calculated by Lumen Method Additional calculations: LPD and Luminaire Efficiency

• Calculation process is repeated for all listed files. • Spacing criterion is calculated and compared with the design. • Luminaires with erroneous photometric data are flagged.

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DISPLAY Images : © Lithonia Lighting

Images : © Philips Lighting Co .

• Calculation results are compiled in a spreadsheet • Results are analyzed using a Pivot-table tool • LPDs are plotted according to Optical system and Lamp-type

• The Hybrid optics category had the highest percentage (56.12%) of luminaires with LPDs less than or equal to 0.8 W/ft2 • 86.96% of the luminaires with LED lamps, out of the 46 considered for this study, had LPDs less than 0.8 W/ft2 • Luminaires with CFL lamps, barring a few exceptions, performed poorly compared to other lamp types, with nearly 50% of them having LPDs higher than 1.0 W/ft2 • Compared to luminaires with conventional optical systems, Hybrid luminaires can offer a more energy efficient solution for applications where direct lighting is desired.

ACKNOWLEDGEMENT This material is based upon work supported by the Energy Efficient Buildings Hub (EEB Hub), an energy innovation hub sponsored by the U.S. Department of Energy under Award Number DE-EE0004261