Plain-English definitions for every lighting and LED retrofit term you'll encounter — from your first utility bill to your commissioning report.
The industry-standard photometric calculation software used by lighting engineers to model foot-candle distribution before fixtures are installed. AGi32 produces visual heat maps showing predicted light levels across a floor plan — allowing verification of OSHA compliance and uniformity targets before the project starts. Echelon uses AGi32 on every commercial and industrial project.
The general, overall illumination of a space — as opposed to task lighting (focused on a work area) or accent lighting (highlighting a feature). In commercial spaces, ambient lighting is typically provided by ceiling fixtures like troffers, high-bays, or recessed downlights.
A device required by fluorescent and HID lamps to regulate the electrical current flowing to the lamp. Ballasts add energy loss as heat, contribute to flicker, and fail more frequently than LED drivers. In an LED retrofit, ballasts are bypassed or removed and replaced with LED drivers.
The angular spread of light emitted by a fixture, measured in degrees. A narrow beam angle (15–30°) concentrates light in a small area — ideal for accent lighting. A wide beam angle (90–120°) spreads light broadly — ideal for general area lighting in warehouses and offices. Beam angle selection is a key variable in photometric design.
Measured in Kelvin (K), CCT describes the warmth or coolness of white light. Lower values (2700K–3000K) appear warm and amber-toned. Higher values (4000K–5000K) appear cool and blue-white, associated with alertness. Most commercial offices use 3500K–4000K. Healthcare and clinical areas often use 4000K–5000K for accurate color assessment.
A 0–100 scale measuring how accurately a light source renders colors compared to natural daylight (100). Standard commercial LED fixtures are typically CRI 80+. Healthcare, retail, and food service applications often require CRI 90+ for accurate color assessment of products, food, and skin tone.
A digital communication protocol for lighting control systems. DALI allows individual fixtures or groups to be controlled, dimmed, and monitored via a network — enabling complex zoning, occupancy response, and integration with building automation systems (BAS). Common in large commercial and industrial facilities requiring granular control.
An automated lighting strategy where photosensors measure available natural light and dim artificial fixtures to maintain a target foot-candle level. Perimeter areas near windows and skylighted spaces typically see 20–40% additional energy savings through daylight harvesting on top of base LED performance. See our lighting controls page.
An independent certification organization that evaluates and lists high-efficiency lighting products. DLC listing is required for most utility rebate programs. Products are tested for efficiency, minimum lumen output, lifetime, and other performance criteria. Echelon specifies DLC-listed products on all projects to ensure rebate eligibility. See our rebates page.
The electronic component that regulates power to an LED fixture, converting AC voltage to the DC voltage LEDs require. Driver quality has a major impact on fixture lifespan, dimming performance, and flicker behavior. High-quality drivers with thermal protection extend LED system life significantly. Driver selection is a critical factor in Echelon's product specification process.
A U.S. Environmental Protection Agency program that certifies energy-efficient products. ENERGY STAR certification for commercial LED fixtures requires meeting specific efficiency, lifetime, and quality standards. Along with DLC, ENERGY STAR qualification is a common requirement for utility rebate programs.
The primary unit of illuminance used in the United States — measuring the amount of light falling on a surface. One foot-candle equals one lumen per square foot. OSHA specifies minimum foot-candle requirements for different work environments: 10fc for general warehousing, 30fc for fine work areas, 50fc for detailed assembly. See our foot-candle guide.
A legacy lighting technology that uses mercury vapor to produce UV light, which then excites a phosphor coating to produce visible light. Common types include T8 and T12 linear tubes. Fluorescent lamps are being phased out under federal and state regulations due to mercury content and energy inefficiency compared to LED. LED retrofits typically achieve 40–55% energy reduction over fluorescent systems.
A category of legacy lighting including metal halide (MH), high-pressure sodium (HPS), and mercury vapor lamps. HID fixtures are characterized by high energy consumption, warm-up/restrike times of 3–15 minutes, and significant maintenance requirements. LED retrofit of HID systems typically delivers 60–75% energy reduction with immediate full-output operation.
A lighting fixture designed for ceiling heights above 20 feet, common in warehouses, manufacturing plants, and distribution centers. LED high-bay fixtures (UFO and linear styles) replace legacy metal halide and fluorescent high-bays at significantly lower wattage — typically 150W LED replacing 400W metal halide. See our warehouse lighting page.
A financing model where a lighting provider installs, owns, and maintains an LED system in exchange for a fixed monthly service fee — rather than a capital purchase. Structured so the fee is lower than the energy cost reduction, creating immediate positive cash flow with zero upfront investment. See Echelon's LaaS program.
A semiconductor device that converts electricity directly into light. LED lighting is 40–80% more efficient than legacy fluorescent or HID sources, lasts 3–10× longer, produces less heat, and contains no mercury. The dominant technology for commercial and industrial lighting as of 2026.
The unit measuring total light output from a source. Unlike watts (which measure power consumption), lumens measure the actual quantity of visible light produced. LED fixtures produce equivalent lumens to legacy sources at a fraction of the wattage — a 150W LED high-bay typically produces the same lumens as a 400W metal halide.
The SI (metric) unit of illuminance, equivalent to one lumen per square meter. Used in international lighting standards. 1 foot-candle = approximately 10.76 lux. While foot-candles are standard in the U.S., lux is used in international compliance documentation and some manufacturer product specs.
A device that detects the presence or absence of occupants in a space and adjusts lighting accordingly — switching off or dimming to a minimum level when the space is vacant. In warehouses and corridors, occupancy-controlled LED can deliver an additional 20–35% energy savings beyond LED performance alone. See our lighting controls page.
The science and practice of measuring and predicting light levels in a space. A photometric study (using AGi32 or DIALux software) models the foot-candle distribution from proposed fixtures before installation — verifying compliance targets, uniformity ratios, and optimal fixture placement. Echelon includes photometric modeling on every project.
A measure of how efficiently electrical power is used, expressed as a ratio from 0 to 1.0. A power factor of 1.0 means all drawn power is used productively. Most commercial LED fixtures have a power factor of 0.90 or higher — significantly better than legacy ballasted systems, which often operate at 0.6–0.8.
A financial incentive offered by utility companies or government programs to businesses that reduce energy consumption through efficiency upgrades. LED lighting rebates typically offset 20–40% of total project cost. Most programs require DLC-qualified products and pre-approval before installation. See Echelon's rebate management service.
The process of upgrading lighting components (lamps, ballasts, drivers) inside existing fixture housings — without replacing the entire fixture. Retrofitting is faster, less expensive, and less disruptive than full fixture replacement, and is appropriate for most commercial LED upgrades. See our commercial retrofit page.
In LED retrofits, ROI measures the financial return relative to the net project cost after rebates. Calculated as annual energy savings ÷ net project cost. Most commercial LED projects achieve payback in 12–36 months. Use our free ROI calculator to estimate yours.
A recessed rectangular light fixture typically installed in drop ceilings, common in offices and commercial spaces. Standard sizes are 2×4, 2×2, and 1×4 feet. LED troffers replace fluorescent lamp-and-ballast systems with direct LED panels, delivering 40–60% energy reduction with improved light quality and no flicker.
LED fixtures capable of adjusting color temperature (CCT) across a range, typically 2700K–6500K. Allows a space to transition from warm, relaxing light to cool, alerting light throughout the day — supporting circadian rhythms and human-centric lighting goals. Common in healthcare, education, and premium office environments.
The ratio of maximum to minimum foot-candle levels across a lit area (expressed as Max:Min). A uniformity ratio of 3:1 or better is typically recommended for most commercial applications — meaning the brightest spot is no more than 3× brighter than the darkest. Poor uniformity creates visual discomfort and safety risks. Verified through AGi32 photometric modeling before installation.
A building-mounted exterior fixture used for perimeter and back-of-building illumination. LED wall packs replace HPS and MH equivalents at 60–75% lower wattage, with improved color rendering and longer service life. Common applications include loading docks, building perimeters, and emergency egress areas. See our parking and exterior page.
The unit of electrical power consumption. In the context of LED retrofits, watt reduction is a key metric — LED fixtures produce the same or greater light output (lumens) at dramatically lower wattage than legacy sources. Note: watts measure power draw, not light output. Lumens measure actual light output. Use our savings calculator to model your wattage reduction.