Length / Width / Height: Room dimensions.
Workplane height: Task plane above floor (desk/surface height).
Target illuminance: Desired average light level (Lux or fc).
Lumens per fixture: Rated lumens from selected luminaire.
Reflectances: Ceiling/wall/floor surface reflectivity used to estimate CU.
CU: Coefficient of Utilization, estimated here from RCR and reflectances.
LLF: Light Loss Factor for maintenance/depreciation effects.
RCR: Room Cavity Ratio, based on room shape and cavity height.
Fixture layout: The required count rounds up from the lumen method so the area-average
usually meets your target. The 3D ceiling pattern is a symmetric, centered grid (partial rows are not
stacked on one side of a corridor). Spacing shows the geometric pitch between grid lines. Est. avg
illuminance and Target shortfall summarize the simple uniform-field assumption.
Site length / width: The lit footprint of your outdoor zone.
Mounting height: Pole or fixture mounting elevation above grade.
Pole setback: Distance in from the site edge used in layout placement.
Maintenance factor: Exterior equivalent to LLF for lumen depreciation and dirt losses.
Advanced mode: Uses spacing, beam, and downlight behavior to approximate min/avg and uniformity.
Uniformity: Reported as Avg/Min; lower values are generally more uniform.
Pole positions: The preview uses a symmetric grid centered inside the setback footprint (not
edge-hugging partial rows along one side). Target shortfall compares area-average result to your
maintained target.
Common Illuminance Guidelines
Typical maintained targets (general design guidance; project and code requirements vary by jurisdiction).
Circulation corridors: 50-100 lux (5-10 fc)
Stairs / exits: 100-150 lux (10-15 fc)
Warehouses (bulk storage): 100-200 lux (10-20 fc)
Warehouses (picking/packing): 200-300 lux (20-30 fc)
Classrooms: 300-500 lux (30-50 fc)
Open offices: 300-500 lux (30-50 fc)
Conference rooms: 300-500 lux (30-50 fc)
Retail sales floor: 500-750 lux (50-75 fc)
Retail feature/display: 750-1500 lux (75-150 fc)
Laboratories (general): 500-750 lux (50-75 fc)
Inspection / fine assembly: 1000-2000 lux (100-200 fc)
Parking garages: 50-100 lux (5-10 fc)
RCR examples
Low RCR (0-3)
Shallow cavity
Light bounces around efficiently
CU is higher
Fewer fixtures needed
Medium RCR (4-7)
Typical office / classroom proportions
CU depends heavily on reflectances
High RCR (8+)
Deep, narrow, tall rooms
Light gets trapped in the cavity
CU drops
More fixtures required
Typical reflectance ranges
Use these as planning defaults when exact finish data is not available.
Walls (color / finish)
White or very light paint: 70-85%
Light gray / beige: 50-70%
Medium tones (taupe, muted colors): 30-50%
Dark paint / wood accents: 10-30%
Gloss and semi-gloss surfaces usually reflect more than matte finishes.
Ceilings (type / color)
White acoustic tile (ACT): 75-85%
Painted gypsum, light color: 70-85%
Exposed deck, medium color: 30-60%
Dark exposed ceilings: 10-30%
Higher ceiling reflectance generally improves CU significantly.
Floors (material / color)
Light polished tile / light vinyl: 30-50%
Medium VCT / laminate / concrete: 20-35%
Dark carpet / dark wood / dark concrete: 5-20%
Floor reflectance affects CU less than ceiling and walls, but still matters.
