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This glossary contains definitions of terminology and concepts commonly used in the energy efficiency community – including electric utilities and lighting.
The descriptions for the nomenclature, terms, and concepts represented here are shared by the majority of the industry.
Do you have another term or concept that needs to be added? Comment below or email us at hello@encentivenergy.com and we’ll add it!
A B C D E F G H I K L M N O P R S T U W
A
| Actual Peak Reduction | The actual reduction in annual peak load (measured in kilowatts) achieved by customers that participate in a utility demand-side management (DSM) program. It reflects the changes in the demand for electricity resulting from a utility DSM program that is in effect at the same time the utility experiences its annual peak load, as opposed to the installed peak load reduction capability (i.e., potential peak reduction). It should account for the regular cycling of energy efficient units during the period of annual peak load. |
| AFUDC | Allowance for Funds Used During Construction |
| Aggregator | Any marketer, broker, public agency, city, county, or special district that combines the loads of multiple end-use customers in negotiating the purchase of electricity, the transmission of electricity, and other related services for these customers. |
| Alternating Current (AC) | An electric current that reverses its direction at regularly recurring intervals. |
| Ambient Lighting | Lighting used to provide general illumination and security. |
| Apparent Power Measurement |
Power measurement method determined by multiplying root mean square (RMS) voltage measurement and RMS current measurement.
|
B
| Baffle | An opaque or translucent component used to shield a light source from direct view. |
| Ballast | A device containing the electrical components used with a discharge lamp to achieve the necessary voltage, current, and waveform for starting and operating the lamp. |
| Ballast Factor | The fractional lumens of a fluorescent lamp(s) operated on a ballast compared to the lumens when operated on the standard (reference) ballasting specified for rating lamp lumens. |
| Bare Lamp | The performance characteristics of a replacement lamp when operated outside of a luminaire or retrofit kit, including the effects of an external ballast (for Type A and Dual-Mode lamps) or driver (for Type C lamps). |
| Base Load | The minimum amount of electric power delivered or required over a given period of time at a steady rate. |
| Beam Angle | The angle between the two opposite directions in which the average intensity is 50% of the center beam intensity as measured in the azimuthal plane perpendicular to, and at the center of, the linear replacement lamp axis. |
| British Thermal Unit (BTU) | A British Thermal Unit (BTU) is a measure of the heating value of a fuel. It is the amount of heat energy required to raise the temperature of one pound of water one degree Fahrenheit. |
| Building Type | A building classification. Commonly designated and referenced to characterize energy consumption based on the building’s primary purpose. |
C
| Candela (cd) | The International System of Units (ISU) base unit for luminous intensity. |
| Chromaticity | The aspects specified by the chromaticity coordinates of the color. It describes the color of the emitted light, independent of its intensity. |
| Clutter | Bright, confusing and excessive groupings of light sources |
| Cogenerator | A generating facility that produces electricity and another form of useful thermal energy (such as heat or steam), that is used for industrial, commercial, heating, or cooling purposes. |
| Color Maintenance | A product’s ability to maintain a specific chromaticity over time. This is the spectral corollary to luminous flux maintenance, which describes depreciation in luminous flux over time. |
| Color Rendition | Effect of an illuminant on the color appearance of objects by conscious or subconscious comparison with their color appearance under a reference illuminant. |
| Commercial Sector | An energy-consuming sector that consists of service-providing facilities and equipment of businesses; Federal, State, and local governments; and other private and public organizations, such as religious, social, or fraternal groups. The commercial sector includes institutional living quarters. It also includes sewage treatment facilities. Common uses of energy associated with this sector include space heating, water heating, air conditioning, lighting, refrigeration, cooking, and running a wide variety of other equipment. Note: This sector includes generators that produce electricity and/or useful thermal output primarily to support the activities of the above-mentioned commercial establishments. |
| Conservation | A reduction in energy consumption that corresponds with a reduction in service demand. Service demand can include buildings-sector end uses such as lighting, refrigeration, and heating; industrial processes; or vehicle transportation. Unlike energy efficiency, which is typically a technological measure, conservation is better associated with behavior. Examples of conservation include adjusting the thermostat to reduce the output of a heating unit, using occupancy sensors that turn off lights or appliances, and car-pooling. |
| Continuous Dimming | A lighting control strategy that varies the light output of a lighting system over a continuous range from full light output to a minimum light output without flickering in imperceptible steps |
| Control Communication | The method and capability of a lighting system to receive and implement commanded changes to the operation, dimmed state, color setting, timing, etc. |
| Control Factor | The fractional energy savings achieved by NLCs to the light source they are controlling. This excludes any energy savings resulting from changes to light sources. |
| Correlated Color Temperature (CCT) | A measure in degrees Kelvin (°K) of light's warmness or coolness. Lamps with a CCT of less than 3,200 °K are pinkish and considered warm. Lamps with a CCT greater than 4,000 °K are bluish–white and considered cool. |
| Correlated Power | The power consumption calculated from the supplied control signal based on a known dimming signal versus power curve. |
| Cost-Based Rates | A ratemaking concept used for the design and development of rate schedules to ensure that the filed rate schedules recover only the cost of providing the service. |
D
| Daylight Harvesting | The capability to automatically affect the operation of lighting or other equipment based on the amount of daylight and/or ambient light present in a space, area, or exterior environment. |
| Demand Response Programs | Demand response programs are incentive-based programs that encourage electric power customers to temporarily reduce their demand for power at certain times in exchange for a reduction in their electricity bills. Some demand response programs allow electric power system operators to directly reduce load, while in others, customers retain control. Customer-controlled reductions in demand may involve actions such as curtailing load, operating onsite generation, or shifting electricity use to another time period. Demand response programs are one type of demand-side management, which also covers broad, less immediate programs such as the promotion of energy-efficient equipment in residential and commercial sectors. |
| Demand-side Management (DSM) | A utility action that reduces or curtails end-use equipment or processes. DSM is often used in order to reduce customer load during peak demand and/or in times of supply constraint. DSM includes programs that are focused, deep, and immediate such as the brief curtailment of energy-intensive processes used by a utility's most demanding industrial customers, and programs that are broad, shallow, and less immediate such as the promotion of energy-efficient equipment in residential and commercial sectors. |
| DesignLights Consortium® (DLC) | A non-profit organization whose mission is to achieve energy optimization by enabling controllability with a focus on quality, people, and the environment. The DLC promotes high-quality, energy-efficient lighting products in collaboration with utilities and energy efficiency program members, manufacturers, lighting designers, and federal, state, and local entities. Through these partnerships, the DLC establishes product quality specifications, facilitates thought leadership, and provides information, education, tools and technical expertise. |
| Diffuser | A device used to distribute light from a source. |
| Dimmers | Can reduce the input power requirements and the rated lumen output levels of incandescent and fluorescent lights. Fluorescent lights need special dimming ballasts. Dimming incandescent lights reduces their efficiency. |
| Dimming Level | Amount of delivered light relative to maximum output, typically reported as a value of the dimming signal from 0-100%. |
| Distribution | The act of distributing electric power using low voltage transmission lines that deliver power to retail customers. |
E
| Efficacy | The ratio of light output to its consumption of power, measured in lumens per watt (LPW), or the ability of a lighting system to produce the desired result. |
| Efficiency | A measure of the effective or useful output of a system compared to the input. |
| Electric Power Grid | A system of synchronized power providers and consumers connected by transmission and distribution lines and operated by one or more control centers. |
| Electric Rate Schedule | A statement of the electric rate and the terms and conditions governing its application, including attendant contract terms and conditions that have been accepted by a regulatory body with appropriate oversight authority. |
| Electric Utility | All enterprises engaged in the production and/or distribution of electricity for use by the public, including investor-owned electric utility companies; cooperatively-owned electric utilities; government-owned electric utilities (municipal systems, federal agencies, state projects, and public power districts). |
| Electricity Congestion | A condition that occurs when insufficient transmission capacity is available to implement all of the desired transactions simultaneously. |
| Electricity Consumption | Represents the power used over time, measured in kilowatt-hours (kWh); reductions in electricity consumption through energy efficiency are also measured in and reported on in kWh. |
| Electricity Demand | The rate at which energy is delivered to loads and scheduling points by generation, transmission, and distribution facilities. |
| Electricity Demand | Represents the instantaneous power required to meet the electrical loads of the utility, measured in kilowatts (kW). |
| Electricity Generation | The process of producing electric energy or the amount of electric energy produced by transforming other forms of energy, commonly expressed in kilowatt hours(kWh) or megawatt hours (MWh). |
| Energy Conservation | Any behavior that results in the use of less energy. Turning the lights off when leaving the room and recycling aluminum cans are both ways of conserving energy. |
| Energy Efficiency Ratio (EER) | The higher the EER rating, the more energy efficient the equipment is. This can result in lower energy costs. This DOE site can show how to calculate potential energy cost savings of a more efficient unit. |
| Energy Efficiency | Using technology that requires less energy to perform the same function. Using a light-emitting diode (LED) light bulb or a compact fluorescent light (CFL) bulb that requires less energy than an incandescent light bulb to produce the same amount of light is an example of energy efficiency. |
| Energy Factor | The measure of overall efficiency for a variety of appliances. |
| Energy Monitoring | The capability of a system, luminaire, or device to report its own energy consumption or the energy consumption of any controlled device via direct measurement or other methodology (i.e. true, apparent, or correlated power). |
| ENERGY STAR® | The government-backed symbol for energy efficiency, providing simple, credible, and unbiased information that consumers and businesses rely on to make well-informed decisions. |
F
| Federal Energy Regulatory Commission (FERC) | An independent agency that regulates the interstate transmission of electricity, natural gas, and oil. FERC also reviews proposals to build liquefied natural gas (LNG) terminals and interstate natural gas pipelines as well as licensing hydropower projects. |
| Federal Power Act | Enacted in 1920, and amended in 1935, the Act consists of three parts. The first part incorporated the Federal Water Power Act administered by the former Federal Power Commission, whose activities were confined almost entirely to licensing non-Federal hydroelectric projects. Parts II and III were added with the passage of the Public Utility Act. These parts extended the Act's jurisdiction to include regulating the interstate transmission of electrical energy and rates for its sale as wholesale in interstate commerce. The Federal Energy Regulatory Commission (FERC) is now charged with the administration of this law. |
| Federal Rates | Rates that apply to the marketing of wholesale power and transmission services provided by government owned or leased facilities to non-Federal customers. This is done through FERC-approved rate schedules or contracts at revenue levels sufficient to repay the Federal charges incurred in providing these services. |
| Fixture | The assembly that holds the lamp in a lighting system. It includes elements designed to control light output, such as a reflector (mirror) or refractor (lens), the ballast, housing, and attachment parts (baffle). |
| Fixture Lumens | The fixture's light output. |
| Fixture Watts | The total power consumed by a fixture. This includes the power consumed by the lamp(s) and ballast(s). |
| Footcandle | A measurement of light received on a surface (equal to the intensity of 1 candle at a distance of 1 foot). Formula: Lumens/Square Foot |
| Forced Outage | The shutdown of a generating unit, transmission line, or other facility for emergency reasons or a condition in which the generating equipment is unavailable for load due to unanticipated breakdown. |
G
| Generation | The act of producing electrical energy from other forms of energy (such as thermal, mechanical, chemical or nuclear); also, the amount of electric energy produced, usually expressed in kilowatt hours (Kwh) or megawatt hours (MWh). |
| Generation | The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in kilowatt hours. |
| Generator Capacity | The maximum output, commonly expressed in megawatts (MW), that generating equipment can supply to system load, adjusted for ambient conditions. |
| Gigawatt (GW) | One billion watts or one thousand megawatts. |
| Gigawatthour (GWh) | One billion watt hours. |
| Glare | Excessive brightness from a light source. The most common types of glare are: direct (light straight into your eyes) and reflected (light reflected from a surface into your eyes). |
| Gross Generation | The total amount of electric energy produced by generating units and measured at the generating terminal in kilowatt hours (kWh) or megawatt hours (MWh). |
H
| High-End Trim (Task-Tuning) | The capability to set the maximum light output to a less-than maximum state of an individual or group of luminaires at the time of installation or commissioning. |
I
| Incandescent Lamp | A lamp in which light is produced by an electrical heating of a filament. |
| Integral Controls | The capability to have sensing and/or control of light output directly integrated or embedded into the lamp or luminaire and available as an option within the lamp or luminaire product model number. |
| Interstate | Sales where transportation of natural gas, oil, or electricity crosses state boundaries. Interstate sales are subject to Commission jurisdiction. |
| Intrastate | Sales where transportation of natural gas, oil, or electricity occur within a single state and do not cross state boundaries. Intrastate sales are not subject to Commission jurisdiction. |
K
| Kilowatt (kW) | One thousand watts. |
| Kilowatt Hour (kWh) | A measure of electricity defined as a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu. |
L
| Lamp Life | The average lifespan for a specific type of lamp. Half of lamps will perform longer than the average; the others will fail before the average. |
| Lamp Lumen Depreciation (LLD) | The measured reduction of lumen output of a lamp over its expected life. |
| Light Color | Lamps are assigned a color temperature according to the kind of light they produce. A "cool light" is at the blue-green end of the spectrum. A "warm light" is at the red end of the spectrum. Visual tasks are easier in "cool light," which provides higher contrast than warm light. |
| Light Pollution | The inappropriate or excessive use of artificial light. Light pollution can have serious environmental consequences for humans, wildlife, and our climate. Components include glare, skyglow, light trespass, and clutter. |
| Light Quality | A measurement of a person's comfort and perception based on the lighting. |
| Light Trespass | Light falling where it is not intended or needed |
| Lighting Controls | Devices used for either turning lights on and off or for dimming. |
| Load | An end-use device or customer that receives power from the electric system. |
| Load Loss | Any significant incident on an electric utility system that results in a continuous outage of 3 hours or longer to more than 50,000 customers or more than one half of the total customers being served immediately prior to the incident, whichever is less. |
| Load-Serving Entity | Secures energy and transmission service (and related Interconnect Operations Services) to serve the electrical demand and energy requirements of its end-use customers. |
| Louver | A series of baffles used to absorb unwanted light or to shield a lamp from view at selected angles. |
| Lumen | The metric unit for the measurement of light output. A lumen is approximately the amount of light that falls on a 1–square–foot surface 1 foot away from a candle. |
| Luminaire | A complete lighting unit that usually includes the fixture, ballasts, and lamps. |
| Luminaire Efficiency | The ratio of the light emitted by the luminaire compared to the light emitted by the enclosed lamps. |
| Luminaire-Level Lighting Controls (LLLC) | Lighting products with wirelessly networked integrated sensors, enabling luminaires within the system to communicate with each other. |
| Luminance | A unit of measurement closely associated with perceived brightness, often expressed in candela per square meter. Luminance is a measure of the photometric flux density per unit solid angle. |
M
| Market-Based Pricing | Prices of electric power or other forms of energy determined in an open market system of supply and demand under which prices are set solely by agreement as to what buyers will pay and sellers will accept. Such prices could recover less or more than full costs, depending upon what the buyers and sellers see as their relevant opportunities and risks. |
| Maximum Demand | The greatest of all demands of the load that has occurred within a specified period of time. |
| Megawatt (MW) | One million watts of electricity. |
| Megawatt Hour (MWh) | One thousand kilowatt-hours or 1 million watt-hours. |
N
| NERC | A nonprofit corporation formed in 2006 as the successor to the North American Electric Reliability Council established to develop and maintain mandatory reliability standards for the bulk electric system, with the fundamental goal of maintaining and improving the reliability of that system. NERC consists of regional reliability entities covering the interconnected power regions of the contiguous United States, Canada, and Mexico. |
| Net Generation | The amount of gross generation less the electrical energy consumed at the generating station(s) for station service or auxiliaries. Note: Electricity required for pumping at pumped-storage plants is regarded as electricity for station service and is deducted from gross generation. |
| Network Lighting Control (NLC) Systems | Lighting systems with a combination of sensors, network interfaces, and controllers that effect lighting changes in luminaires, retrofit kits, or lamps. |
| Networking of Luminaires and Devices | The capability of individual luminaires and control devices to exchange digital data with other luminaires and control devices on the system. |
O
| Open-Circuit Voltage | The voltage applied by ballast to a lamp during startup. The voltage quickly decreases to operating voltage once the lamp ignites. |
| Outage | The period during which a generating unit, transmission line, or other facility is out of service. |
P
| Passive Infrared Occupancy Sensor | A lighting control system that uses infrared beams to sense motion. When beams of infrared light are interrupted by movement, the sensor turns on the lighting system. If no movement is sensed after a predetermined period, the system turns the lights off. |
| Peak Demand | The maximum load during a specified period of time. |
| Personal Control | The capability for individuals to adjust the illuminated environment of a light fixture or group of light fixtures in a specific task area to their personal preferences, via networked means. |
| Photocells | Sensors that turn lights on and off in response to natural light levels. Some advanced models can slowly dim or increase the lighting. |
| Power | The rate of producing, transferring, or using energy, most commonly associated with electricity. Power is measured in watts and often expressed in kilowatts (kW) or megawatts (mW). Also known as "real" or "active" power. |
| Power Factor | An attribute of ballast describing how effectively it converts current and voltage into usable power. High–power factor ballasts have a rating of 0.9 or more. See ballast factor. |
| Power-Dimming Curve | A curve representing the relationship between a dimming signal and corresponding power output as a function of control signal from 0-100%. |
| Public Utility Regulatory Policies Act of 1978 | The Public Utility Regulatory Policies Act of 1978, passed by the U.S. Congress. This statute requires States to implement utility conservation programs and create special markets for co-generators and small producers who meet certain standards, including the requirement that States set the prices and quantities of power the utilities must buy from such facilities. |
R
| Rate | The authorized charges per unit or level of consumption for a specified time period for any of the classes of utility services provided to a customer. |
| Rate Base | The value of property upon which a utility is permitted to earn a specified rate of return as established by a regulatory authority. |
| Rate of Return | The ratio (percentage) of profits (or earnings) compared to capital or assets. |
| Rate Schedule | The rates, charges, and provisions under which service is supplied to the designated class of customers. |
| Rated Power | Maximum rated luminaire or zonal wattage without controls enabled. |
| Reflector | A device used to reflect light. |
| Refractor | A device used to redirect the light flow from a source, primarily by bending the wave light (refraction). |
| Reporting Interval | The interval in which power and/or energy measurements are reported as a single value (e.g. every 5 minutes, every 15 minutes, hourly, or daily). |
| Restriking Time | The time required for a lamp to relight. Fluorescent lamps usually only need a second or two before relighting. |
S
| Scheduled Outage | The shutdown of a generating unit, transmission line, or other facility for inspection or maintenance, in accordance with an advance schedule. |
| Scheduling | The capability to automatically affect the operation of lighting equipment based on time of day, week, month, or year. |
| Seasonal Energy Efficiency Ratio (SEER) | The higher the SEER rating, the more energy efficient the equipment is. A higher SEER can result in lower energy costs. |
| Skyglow | The brightening of the night sky over inhabited areas |
| Space Type | A classification of a subspace within a building. Commonly designated and referenced to characterize energy consumption for a specific use within a building (e.g.open office, hall, breakroom). |
| Spectral Power Distribution (SPD) | Describes the power emanating from a light source as a function of wavelength. The information can be presented graphically or as a numerical table. |
| Stability | The ability of an electric system to maintain a state of equilibrium during normal and abnormal conditions or disturbances. |
| State Change | Change in luminous output caused by a triggering of control strategy (e.g. occupancy, scheduling, daylighting, etc.). An event-based interval reporting method utilizes state changes, rather than defined time intervals, to report power or energy data. |
| Stepped Dimming | A lighting control strategy that varies the light output of a lighting system in one or more predetermined steps of greater than one percent of full output. The changes between levels are generally perceptible. |
| Striking | Starting a fluorescent lamp. |
| Substation | Facility equipment that switches, changes, or regulates electric voltage. |
T
| Task Lighting | Task lighting is used to provide direct light for specific activities without illuminating the entire area. |
| Terawatt Hour | One trillion watt hours. |
| Time Clocks | Lighting control devices that automatically turn lights on and off. Time clocks are typically used for security and safety. |
| Timers | Lighting control devices that turn the lights off after short intervals. |
| Transformer | An electrical device for changing the voltage of alternating current. |
| Transmission | Moving bulk energy products from where they are produced or generated to distribution lines that carry the energy products to consumers. |
| Transmission Line | A system of structures, wires, insulators and associated hardware that carry electric energy from one point to another in an electric power system. Lines are operated at relatively high voltages varying from 69 kV up to 765 kV, and are capable of transmitting large quantities of electricity over long distances. |
| Transmission System | An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers or is delivered to other electric systems. |
| True Power Measurement | Power measurement method where instantaneous voltage measurement is multiplied by instantaneous current measurement, then accumulated and integrated over a specific time period of at least one complete cycle. |
U
| Ultrasonic Occupancy Sensor | A lighting control system using high–frequency sound waves pulsed through a space to detect movement by depth perception. When the frequency of the sound waves change, the sensor turns on the lighting system. After a predetermined time with no movement, the system turns the lights off. |
| Unified Glare Rating (UGR) | A measure of the discomfort produced by a lighting system along a psychometric scale of discomfort. |
| Utility Distribution Company | The entities that will continue to provide regulated services for the distribution of electricity to customers and serve customers who do not choose direct access. Regardless of where a consumer chooses to purchase power, the customer's current utility, also known as the utility distribution company, will deliver the power to the consumer. |
W
| Watt (W) | The unit of electrical power equal to one ampere under a pressure of one volt. A Watt is equal to 1/746 horsepower. |
| Watt Hour (Wh) | The electrical energy unit of measure equal to one watt of power supplied to, or taken from, an electric circuit steadily for one hour. |
| Wires Charge | A broad term referring to fees levied on power suppliers or their customers for the use of the transmission or distribution wires. |
Sources:
eia.gov | fs.fed.us | DLC® Energy Savings from NLCs with/without LLLC Report | ies.org | DLC® SSL Qualification Requirements V 5.0 V5.1 | ferc.gov | darksky.org | energystar.gov | nerc.com | neea.org
