Skip to content

Energy-Efficiency Terms

Energy Terms

  • Biomass – Energy from organic matter used directly for heat or to power a generator for electricity.
  • Btu – The British thermal unit (BTU or Btu) is a unit of heat energy. Btu is defined as the amount of heat required to raise the temperature of one pound of water by 1 degree Fahrenheit. In the energy industry, energy content is typically defined in terms of Million Btu, or MMBtu. (1 kWh = 3414.42 Btus, 1 Therm = 100043 Btus)
  • CEE (Consortium for Energy Efficiency) – CEE is a consortium of efficiency program administrators from across the U.S. and Canada who work together on common approaches to advancing efficiency. Through joining forces, the individual efficiency programs of CEE are able to partner not only with each other, but with other industries, trade associations, and government agencies. By working together at CEE, administrators leverage the effect of their funding dollars, exchange information on effective practices and, by doing so, and achieve greater energy efficiency for the public good.
  • Efficiency – Using less energy to perform the same amount of work.
  • EER (Energy Efficiency Rating) – A measure of how efficient space cooling equipment is. It is a ratio of the cooling output and the input power.The higher an EER rating, the more efficient the equipment.
  • Energy – the ability to do work (measured in Joules, Btu or kWh)
  • Heating Degree Days (HDD) – The number of degrees that a daily average temperature is below a base temperature (typically 65°), summed up daily for an entire year. The heating degree days for a certain climate or locations can be used to estimate how much energy will be needed to keep a space warm.
  • Kelvin (K) – In lighting, the Kelvin scale is used to describe the color of light in degrees. Ex 25000 = Soft white (warm), 50000 = daylight
  • Kilowatts (kW) – A measure of electric power. One kilowatt is 1,000 watts.
  • Kilowatt Hours (kWh) – A measure of electrical energy, derived by multiplying the power used by the time in which it was used. One kilowatt hour is equal to one kilowatt of electric power used for one hour.
    For example: A 100 watt light bulb burns for 10 hours. 100 watts x 10 hours = 1000 watt hours of energy (1 kWh).
  • Passive Solar Design – An architectural design to utilize the sun’s natural energy for a home’s internal heating and cooling climate control.
  • Phantom Loads – An energy draw that continues to use electricity even after an appliance is turned off, i.e. entertainment centers, computers, garage door openers, microwaves, stoves with clocks, and any lights left on continually.
  • Photovoltaic (PV) – Generating electricity directly using natural sunlight.
  • Renewable Energy – An energy source that renews itself in nature, such as solar, wind, hydro and geothermal.
  • Seasonal Energy Efficiency Rating (SEER) – The SEER rating of a unit is the cooling output in Btu during a typical cooling-season divided by the total electric energy input in Watt-hours during the same period. The higher the unit's SEER rating the more energy efficient it is.
  • Solar Thermal – A system whereby collector panels heat water or other fluids to be used and stored for domestic hot water or space heating systems.
  • Sustainability – Living, traveling and doing business in a manner that enhances economic and community well-being without depleting natural resources faster than they are restored.
  • Therm – A therm is a unit of natural gas equal to 100,000 British thermal units of energy. Natural gas use is typically billed by the therm.
  • Wind Turbine – A wind turbine converts the energy of wind into kinetic energy. This energy can either be used directly, or it can be used to power a generator and produce electricity.

Lighting Terms

  • Accent lighting – Lighting used to emphasize an object or area.
  • Ambient lighting – General illumination lighting.
  • Ballast – A ballast controls the current delivered to a fluorescent or HID lamp. Most ballasts also convert the line voltage into the proper voltage and waveform needed to start and operate the lamp.
  • Bulb – The material that encases a lamp.
  • CFL – Compact fluorescent light bulb
  • Dimmer – A device used to control the voltage or current available to power the lamp which controls the intensity of a lamp's emitted light.
  • Downlight – A small recessed, surface-mounted, or suspended direct-lighting unit that directs light downward. Common in residential applications.
  • Fixture – A complete lighting unit consisting of a lamp or lamps and the parts designed to distribute the light, position and protect the lamp(s), and connect the lamp(s) to the power supply.
  • High-bay lighting – Interior lighting in rooms where the roof truss or ceiling height is greater than approximately 7.6 meters (25 feet) above the floor.
  • High-intensity discharge (HID) – High output lighting used most commonly used outdoors and in spaces with high-ceilings. Mercury vapor, metal halide, and high-pressure sodium lamps are all considered to be HID sources. HID lamps come in a large range of wattages and are generally moderately efficient and long-lived.
  • High-pressure sodium (HPS) – light is produced by radiation from sodium vapor in a high-intensity discharge lamp. Light from HPS sources tends to be yellow or orange in color.
  • High output (HO) – Ballasts and fluorescent lamps designed to operate at higher power than standard products of the same size in order to provide greater light output.
  • Indirect lighting – A luminaire that distributes 90 to 100 percent of its emitted light upward can be classified as indirect.
  • Instant start (IS) – An instant-start ballast is designed to start a lamp extremely quickly. Lamps are started with a high voltage instead of by preheating lamp cathodes.
  • Lamp – In the lighting industry, "lamp" is the term for a light source. Incandescent light bulbs and CFLs are both considered "lamps," and table and desk lamps are referred to as fixtures.
  • LED – Light-Emitting Diode
  • Lens – A glass or plastic element designed to control the distribution and direction of light rays.
  • Lumen – Measure of Light output
  • Luminaire – An industry term for a complete lighting unit that consists of one or more lamps, ballasts to provide power to the lamps, components to connect the lamps or ballasts to a power source, and parts designed to distribute light from the lamps.
  • Magnetic ballast – Power circuit designed to limit current and provide necessary starting voltage for discharge lamps. A magnetic ballast consists of one or more magnetic coils and optional capacitors.
  • Metal halide (MH) – One type of HID light source. Metal halide lighting produce a relatively high output of whitish light.
  • Occupancy Sensor – An electronic device that can control lighting, equipment, or appliances so that equipment is only turned on when people are present.
  • PAR – parabolic aluminum reflector or parabolic aluminized reflector
  • Photocell – A light-sensing device used to control fixtures and dimmers.
  • Program start – A lamp starting method designed to extend lamp life, especially where lamps are switched on and off frequently. Users will experience a short delay after turning on lights.
  • Rapid start – A rapid-start ballast is designed to start a lamp fairly quickly. Lamps are started with a high voltage instead and by preheating lamp cathodes.
  • Rated life – A light bulb’s estimated lifetime measured in hours. For all light bulbs, lifetime is determined by operating a sample of bulbs according to industry test standards. The time that half of the test sample fails is considered rated life. By definition, some lamps will fail before their rated life and some will operate beyond their rated life. The ENERGY STAR CFL criteria require additional testing to show that the sample can withstand a number of short start cycles and monitors early failures throughout testing.
  • T# – A designation of lamp type, as in T8, T12, and so on. T stands for tubular; the number describes lamp diameter in one-eighth-inch increments. A T8 lamp is eight-eighths of an inch (or 1 inch) in diameter; a T12 is twelve-eighths of an inch (or 1 and one-half inches) in diameter.
  • Troffer – A recessed lighting unit having its opening flush with the ceiling in which it is installed. This term is derived from "trough" and "coffer."

Utility Terms

  • Blended rate – Total electricity costs divided by the total kWh used in a period of time. A blended rate will incorporate factors such as facility and demand charges into a simple average of $/kWh of electricity used.
  • Demand charges – A charge that reflects the maximum amount of power a customer requires at a specific time.
  • Demand, electric – the maximum of energy required by a customer at a specific time. Demand is generally averaged over a 15 minute period. Demand is measured in kilowatts (kW).
  • Grid – The interconnected network of transmission lines used to deliver electricity from where it is generated to end users.
  • Net Metering – Excess energy created by renewable sources can be metered and credited toward a customer’s energy bill.
  • On peak – The times when a utility is operating near or at its highest capacity. On peak times are generally from 6am – 9am to 6pm – 9pm from Monday through Friday.
  • Off peak – Times when electricity demand is low, usually at night and on weekends. Utilities typically charge less for maximum demand during off-peak hours.