Quick Lighting Calculator

Variables

Room Width (ft)

Room Length

Luminaire Height 8

Lumens per Lamp

Watts Per Lamp

Coefficient of Utilization

Calculated

Room Cavity Ratio

Maintained Illuminance (fc)

Number of Luminaires 3Lamps per Luminaire

Maintained Illuminance (fc)

Watts per Sq.Ft.

Constants

Lamp Lumen Depreciation 0.8

Luminaire Dirt Depreciation 0.8

Ballast Factor 0.95

Work Plane (ft) 2.5

Luminaires Required

Desired Illuminance (fc)

Lamps per Luminaire

Fixtures Required

Watts per Sq.Ft.

Project Lighting SummaryProject:Engineer:

Date:

Maint. Total

Room / Area (fc) Width Length Watts

Rm 101 50 20 18 700

Rm 102 30 15 20 450

Project Average Watts / Sq.Ft.

Watts

per SqFt

1.9

1.5

1.7

Instructions

In the Quick Lighting Calculator, all white boardered cells require input by the designer. The Room Cavity Ratio is calculated and shown for the designer to use in selecting the Coefficiant of Utilization. For rooms with lay-in luminaires, fixture height will be the room height. After the basic information is entered use the "Maintained Illuminance" or the "Luminaires Required" areas for the desired function. The areas calculate independantly, but both use the common data above.

The Project Summary page may be used to summarize the project lighting values. After the total watts are computed for the desired lighting levels in the Quick Calculator, the designer may move these numbers to this spreadsheet where the room W/SqFt and the project average W/SqFt are automatically calculated. When printing the Project Summary or Quick Calculator pages, go to File/Print Setup and select "black & white" in the Print Options.

Room surface reflectance is not a shown field - this information is part of the manufacturer's CU information sheet and should be used by the engineer to select the proper CU.