🏠Residential Lighting Applications
Room-by-Room Lighting Guidelines
Living Areas
Living Room General: 100-200 lux (9-18 fc)
Reading Area: 300-500 lux (28-46 fc)
Dining Table: 200-300 lux (18-28 fc)
Kitchen General: 300-400 lux (28-37 fc)
Kitchen Task: 500-800 lux (46-74 fc)
Use dimmer controls for flexibility
Bedrooms & Bathrooms
Bedroom General: 100-200 lux (9-18 fc)
Bedside Reading: 300-500 lux (28-46 fc)
Closet: 200-300 lux (18-28 fc)
Bathroom General: 200-300 lux (18-28 fc)
Bathroom Mirror: 400-600 lux (37-56 fc)
Avoid glare around mirrors
LED Retrofit Planning
Replacing Incandescent
60W incandescent = 800 lumens
LED equivalent: 8-10W (100 lm/W)
Energy savings: 85% reduction
Cost per year: $7 vs $52
Payback period: 6-12 months
Choose 2700K-3000K for warm feel
Replacing Fluorescent
4ft T8 32W = 2,850 lumens
LED equivalent: 18-22W (130-150 lm/W)
Energy savings: 40-50% reduction
Maintenance: 50,000hr vs 20,000hr
Better dimming capability
No ballast required, instant on
🏢Commercial Lighting Design
Office Environment Standards
Task-Based Lighting
Computer Work: 300-500 lux
Screen luminance: 100-200 cd/m²
Surround ratio: 3:1 max contrast
Ceiling luminance: 200 cd/m² max
Reduce glare with indirect lighting
Use task lights for detailed work
Open Office Layout
General illuminance: 300-500 lux
Uniformity ratio: 0.6 minimum
Fixture spacing: 1.2 × mounting height
Avoid direct/indirect ratio > 2:1
Consider daylight integration
Provide individual control options
Retail Lighting Strategies
General Merchandise
General area: 500-1000 lux (46-93 fc)
Display areas: 1500-3000 lux (140-280 fc)
Accent lighting: 3× general level
Color temperature: 3000-4000K
CRI: 90+ for accurate colors
Use track lighting for flexibility
Specialty Retail
Jewelry: 2000+ lux, high CRI
Clothing: 1000 lux, good color
Electronics: 750 lux, cool white
Grocery: 800 lux produce, 500 aisles
Avoid UV damage on merchandise
Layer ambient, task, and accent lighting
📏Light Measurement Techniques
Using Light Meters
Measurement Setup
Hold meter at work plane height (30" typical)
Point sensor toward ceiling for general lighting
Take readings at multiple locations
Account for occupancy and furniture
Measure during steady-state conditions
Average 9-point grid for uniformity
Common Measurement Errors
Shadow from person/meter affects reading
Cosine correction errors at steep angles
Temperature drift in uncalibrated meters
Spectral mismatch with LED sources
Reflections from nearby surfaces
Calibrate annually for accuracy
Daylight Integration
Daylight Factors
Overcast sky: 10,000-25,000 lux
Clear sky: 80,000-120,000 lux
Window transmittance: 0.7-0.8
Daylight factor = Indoor/Outdoor lux
Target DF: 2-5% for good daylighting
Use sensors for automatic dimming
Control Strategies
Photosensor placement: avoid direct sun
Control zones: perimeter vs interior
Dimming range: 100% to 10% minimum
Time delay: 5-15 minutes to avoid cycling
Manual override capability required
Energy savings: 20-60% typical
⚡Energy Efficiency Applications
Lighting Power Density Compliance
Building Code Requirements
ASHRAE 90.1 Office: 11 W/m² (1.0 W/ft²)
California Title 24: 7-9 W/m²
IECC Commercial: 9-12 W/m²
LEED v4: 30% below ASHRAE
Controls required: occupancy, daylight
Use lighting design software for compliance
Energy Calculation Example
Office space: 500 m² × 500 lux target
LED efficiency: 150 lm/W system
CU = 0.7, LLF = 0.85, DF = 0.9
Required power: 500/(150×0.7×0.85×0.9) = 6.2 W/m²
Annual energy: 6.2 × 500 × 2500hr = 7,750 kWh
Cost: $775/year at $0.10/kWh
Smart Lighting Systems
Occupancy-Based Control
PIR sensors: 15-25% energy savings
Ultrasonic sensors: better coverage
Dual-technology: reduces false switching
Time delay settings: 5-30 minutes
Dimming to 20% vs full off
Network sensors provide usage data
Tunable White Lighting
Circadian rhythm support: 2700K-6500K
Morning: cool white (5000K+)
Evening: warm white (2700K-3000K)
Productivity studies show 5-15% improvement
Health benefits: better sleep patterns
Premium cost but measurable benefits
💡Illuminance Conversion Tips
Quick Conversions
Memory Aids
1 foot-candle ≈ 11 lux (actually 10.764)
100 lux ≈ 9 foot-candles
500 lux ≈ 46 foot-candles (office standard)
1000 lux ≈ 93 foot-candles (detailed work)
Natural Light References
Full moon: 0.25 lux
Overcast day: 1,000-25,000 lux
Bright sun: 100,000 lux
Good reading light: 500-1,000 lux
Design Guidelines
Age-Related Factors
Age 40+: Need 2× more light
Age 60+: Need 3× more light
Reduce glare sensitivity
Higher contrast ratios needed
Quality Factors
Uniformity ratio: 0.6 minimum
Glare rating: UGR < 19 office
Color rendering: CRI 80+ general, 90+ retail
Flicker: < 5% at all dim levels