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Lighting Calculator
Fixtures needed, total watts, amps, and ASHRAE 90.1 LPD pass/fail for any room type
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Room Dimensions
Room Type
IES Target
50 fc
ASHRAE 90.1 Max LPD
0.82 W/sq ft
Fixture & Electrical
Delivered lumen output per fixture
100 lm/W efficacy
Lighting Design Reference
CU (0.65)Coefficient of Utilization — fraction of fixture lumens reaching the work plane; varies with room geometry and surface reflectances
LLF (0.80)Light Loss Factor — accounts for lamp lumen depreciation, dirt accumulation, and ballast/driver losses over service life
FootcandlesIES RP-1 (Office), RP-7 (Industrial/Warehouse), RP-2 (Retail) illuminance recommendations by task and space type
ASHRAE 90.1Energy standard setting maximum LPD limits by space type; compliance required for most commercial construction permits
NEC 210.19Branch circuit conductor sizing; continuous lighting loads must not exceed 80% of circuit breaker rating
NEC 220.14(D)Track lighting load calculated at 150 VA per 2 ft of track regardless of connected fixture count
Professional disclaimer: Lighting designs must comply with IES illuminance recommendations, ASHRAE 90.1, local energy codes, and ADA/egress requirements. Emergency lighting, exit signs, lighting controls, and dimming are not included in this calculation. Consult a licensed electrical engineer or lighting designer for permitted construction documents.
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