42 essential terms for facility managers, contractors, and engineers. From lumens to DLC Premium — every LED lighting concept explained clearly.
The most common commercial LED dimming protocol. A low-voltage (0-10V DC) signal controls light output from 0% to 100%. Simple two-wire control. Compatible with most building automation systems, occupancy sensors, and daylight harvesting controllers.
A pole-mounted outdoor fixture shaped like a shoebox, used for parking lots, roadways, and outdoor commercial areas. Mounts on 15-40 ft poles. Typical LED wattages: 100W-600W replacing 250W-1500W metal halide. Type III or Type V distribution is most common.
Energy Standard for Buildings Except Low-Rise Residential, published by ASHRAE (American Society of Heating, Refrigerating, and Air-Conditioning Engineers). Sets maximum lighting power density (LPD) and control requirements. Referenced by most US building codes outside California (which uses Title 24).
The angle between the two directions where light intensity drops to 50% of peak. Narrow beam (15-30°): spot lighting, high ceilings. Medium beam (60-90°): general area lighting. Wide beam (120°+): flood lighting, low ceilings. Choose based on mounting height and desired uniformity.
A device that regulates current in fluorescent and HID (metal halide, HPS) fixtures. Consumes 10-20% additional power (ballast loss). LED fixtures use drivers instead of ballasts. When calculating energy savings from LED retrofit, include ballast wattage in the "before" number.
A 0-100 scale measuring how accurately a light source renders colors compared to natural light. CRI 80+ is standard for commercial LED. CRI 90+ is recommended for retail, art galleries, and color-critical applications. LED CRI is typically 70-90, compared to metal halide at 65-70.
A non-profit that maintains a Qualified Products List (QPL) of energy-efficient commercial lighting. DLC listing is required for most utility rebates in the US. Two tiers: DLC Standard and DLC Premium (higher efficacy requirements). Over 300,000 products listed.
The electronic power supply that converts AC line voltage (120-277V or 347-480V) to the DC voltage/current needed by LEDs. Driver quality determines fixture lifespan, dimming performance, and efficiency. Mean Well and Inventronics are leading commercial-grade driver brands.
A digital lighting control protocol that allows individual fixture addressing and grouping. Supports 64 devices per DALI bus. More flexible than 0-10V but more expensive. Common in modern office buildings and intelligent lighting systems.
An automatic control strategy that dims artificial lights when natural daylight is available. Uses photosensors to measure ambient light levels. Can save 15-40% additional energy beyond LED conversion. Required by Title 24 in daylight zones within 15 feet of windows and under skylights.
Fixtures that minimize light pollution by directing all light downward (0% uplight). Required in many municipalities near astronomical observatories and in environmental protection areas. Also reduces wasted energy from light directed at the sky. BUG (Backlight-Uplight-Glare) rating of U0 qualifies.
A utility charge based on peak power consumption (kW), separate from energy charges (kWh). Can represent 30-50% of a commercial electric bill. LED reduces both energy consumption and peak demand, providing double savings. Demand charges are typically $5-25 per kW per month.
Lumens produced per watt of electricity consumed. Modern commercial LEDs achieve 130-200 lm/W. DLC Premium requires ≥135 lm/W for most categories. Higher efficacy = more light for less energy. Metal halide averages 80-100 lm/W.
A battery system that powers LED fixtures during power outages. Code requires emergency lighting in egress paths for minimum 90 minutes at 1 FC average. Options: integral battery (built into fixture), remote battery pack, or central inverter system. LED's low wattage means smaller, cheaper emergency batteries.
A unit of illumination equal to one lumen per square foot. IES standards specify minimum foot-candle levels: warehouses need 30 FC, offices 50 FC, retail 50-100 FC, parking lots 1-5 FC. One foot-candle equals approximately 10.764 lux.
A fixture designed for mounting heights of 20+ feet. Two main types: UFO (round, compact, versatile) and linear (rectangular, good for aisle lighting). Typical wattages: 100W (20 ft), 150W (25 ft), 200W (30 ft), 240W (35 ft). Used in warehouses, gyms, manufacturing, retail big-box stores.
A two-digit code indicating protection against solids and liquids. First digit (0-6): dust protection. Second digit (0-9): water protection. IP65 = dust-tight + water jets. IP66 = dust-tight + powerful water jets. IP67 = dust-tight + temporary submersion. Outdoor fixtures need IP65 minimum.
Measures resistance to mechanical impact, from IK00 (no protection) to IK10 (20 joules). IK08 = 5 joules (typical for commercial). IK10 = 20 joules (vandal-resistant, recommended for parking garages and public areas).
A standardized photometric data file (.ies) used in lighting design software like AGi32, DIALux, and Visual. Contains the light distribution pattern (candela values at multiple angles) of a specific fixture. Essential for accurate foot-candle calculations and code compliance documentation.
The total amount of visible light emitted by a source. A 150W LED high bay typically produces 22,500-26,250 lumens. Higher lumens = brighter fixture. Not to be confused with watts, which measure energy consumption.
The SI unit of illumination equal to one lumen per square meter. 1 foot-candle = 10.764 lux. Used internationally; foot-candles are more common in the US.
The number of hours until an LED produces 70% of its initial light output. Commercial LEDs are typically rated at L70 = 100,000 hours (11+ years at 24/7 operation). Compare to metal halide at 20,000 hours and fluorescent at 30,000 hours.
The installed lighting power per unit area, measured in watts per square foot (W/ft²). Title 24 and ASHRAE 90.1 set maximum LPD values by space type. Warehouse: 0.6 W/ft², Office: 0.8 W/ft², Retail: 1.0 W/ft². LED makes it easy to stay under these limits due to high efficacy.
An IES standard for testing complete LED luminaires. Measures total lumens, efficacy (lm/W), CCT, CRI, chromaticity, and electrical characteristics. LM-79 reports are required for DLC listing and utility rebate applications. Tests must be performed by accredited laboratories.
An IES standard for testing LED package/module lumen depreciation over time. Requires minimum 6,000 hours of testing at specified temperatures. Used with TM-21 to project long-term lumen maintenance (L70 lifetime). Not a fixture-level test — that's LM-79.
The vertical distance from floor to fixture. Determines fixture wattage and beam angle selection. Typical mounting heights: 15-20 ft (warehouse low bay), 20-30 ft (warehouse high bay), 30-40 ft (distribution center), 25-40 ft (pole-mounted area lights).
A device that detects human presence and controls lighting automatically. PIR (passive infrared) detects body heat; ultrasonic detects motion; dual-technology combines both. Required by Title 24 and ASHRAE 90.1 in most commercial spaces. Saves 30-50% in intermittent-use areas.
The ratio of real power to apparent power, ranging from 0 to 1.0. Commercial LED fixtures should have PF ≥ 0.90. Low power factor wastes energy and can incur utility penalties. DLC requires PF ≥ 0.90 for most categories.
The time required for energy and maintenance savings to equal the cost of an LED upgrade. Calculated as: Net Project Cost ÷ Annual Savings. Commercial LED retrofits typically achieve 6-24 month payback. Utility rebates can reduce payback by 30-50%.
The science of measuring visible light. In lighting design, photometric testing measures a fixture's light output, distribution, efficacy, and color quality. Results are published in IES files and photometric reports. Independent labs (like LM-79 test labs) perform standardized photometric testing.
Replacing existing lighting with LED while keeping the original housing/structure. Options include: retrofit kits (new LED modules in old housings), direct wire LED tubes (bypass ballast), and full fixture replacement. Full replacement typically provides the best ROI and light quality.
Built-in protection against voltage spikes from lightning or grid switching. Measured in kilovolts (kV). Standard commercial LED: 6kV. Enhanced outdoor: 10kV. Critical for parking lot and area lights exposed to weather. Without surge protection, a single lightning strike can destroy multiple fixtures.
A measure of electrical noise generated by an LED driver, expressed as a percentage. Lower THD = cleaner power. Commercial LEDs should have THD < 20%. High THD can cause interference with other equipment and increase energy losses.
California's Building Energy Efficiency Standards (Part 6 of the California Building Code). Sets minimum lighting power density (LPD) requirements for all commercial buildings. Requires automatic controls (occupancy sensors, daylight harvesting) in most spaces. Updated every 3 years; current version is 2022 Title 24.
IESNA classification of outdoor luminaire light patterns. Type I: narrow linear (pathways). Type II: slightly wider (roadways, bike lanes). Type III: wide forward throw (parking lots, building perimeters). Type IV: forward throw semicircular (building-mounted wall packs). Type V: symmetric circular (parking lot center poles).
A recessed rectangular light fixture that fits into a drop ceiling grid. Standard sizes: 2×2 ft and 2×4 ft (matching ceiling tile dimensions). Common in offices, schools, hospitals. LED troffers typically consume 25-50W, replacing 96W fluorescent 3-lamp T8 troffers.
The complete cost of a lighting system over its lifetime, including purchase, installation, energy, maintenance, and disposal. LED has the lowest 10-year TCO of any commercial lighting technology despite higher upfront cost, due to 50-75% energy savings and near-zero maintenance.
Safety certifications from Underwriters Laboratories (UL) or Intertek (ETL). Required by US building codes for electrical products. UL and ETL listings are equivalent — both confirm the product meets US safety standards. Look for the UL or ETL mark on every commercial fixture.
The ratio of minimum to average illumination (min/avg) across a surface. Higher uniformity = more even light distribution. IES recommends: warehouses ≥ 0.5, offices ≥ 0.6, parking lots ≥ 0.25. Poor uniformity creates dark spots and safety hazards.
A building-mounted outdoor fixture for perimeter security lighting, loading docks, and entryways. Replaces 70-400W HPS or MH fixtures. LED wall packs range from 20W to 120W. Available in full cutoff (dark sky compliant) and semi-cutoff versions.