Handbook of Electric Power Calculations, Third Edition
A powerful calculations tool for electric power engineers and technicians, this book offers essential, step-by-step procedures and examples for solving a wide array of electric power problems.
TABLE OF CONTENTS Handbook of Electric Power Calculations, Third Edition
Section 20: LIGHTING DESIGN
Charles L.Amick, P.E., F.I.E.S., L.C.
Lighting Consultant
INTRODUCTION
Lighting accounts for 20 to 25 percent of all electricity consumed in the United States, and as a nation, we spend billions on it each year. [1] Electric lighting represents about half of all electricity used in modern commercial buildings. [2]
Lighting design involves:
Establishing proper illuminance levels for the visual tasks to be performed.
Knowledge of the physical characteristics of space to be illuminated.
Selecting and locating luminaries (style appropriate for space, efficacy, color, and lumens per watt of lamps, etc.).
Calculating what portion of the generated light will reach the work plane.
Computing the number of luminaires needed.
Developing a lighting system maintenance plan for the owner to follow.
[*]Original work by John P.Frier, Former Lighting Application Specialist, General Electric Company.
[1] DOE Expected to Adopt New Energy-Efficient Lighting Standards, Lighting Design and Application, Dec. 1999, Vol. 29, No. 12, p. 17.
[2] Lighting Design Practice, California Energy Commission, March, 1990, p. 1.
AVERAGE ILLUMINANCE
Many lighting projects call for reasonably uniform illuminance levels for work or other activities located throughout the space. Additional supplementary luminaires can provide higher levels that may be needed for more difficult visual tasks at specific work stations.
Calculation Procedure
The procedure generally employs the lumen method. The lumen is the unit of luminous flux, the latter being the integrated product of the energy per unit wavelength and the spectral luminous efficacies. Although luminous flux is the time rate of...
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