Energy Glossary | My Business | Mississippi Power | A Southern Company
  • Katrina 2005-2015
  • Katrina 2005-2015
  • Energy Glossary

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    A
    active solar The use of mechanical devices such as collectors, storage tanks, and pumps to capture heat energy from the sun for use in space heating/cooling and water heating systems. Other applications include the generation of electricity from solar energy.
    actual demand The maximum rate at which energy is used, as measured in kilowatts (kW) in 15 or 30 minute intervals.
    annual fuel utilization efficiency (AFUE) The total heating output of a furnace during its normal annual usage period for heating, divided by the total energy used.
    B
    batts Pressed mats of glass fiber, mineral wool or other insulating material sold in 4' and 8' lengths.
    blankets Pressed mats of glass fiber, mineral wool or other insulating material sold in continuous rolls that may be cut to any lengths.
    British thermal unit (BTU) A measure of heat equal to the amount of heat necessary to raise the temperature of one pound of water one degree F.
    building envelope The physical area that separates a building’s interior and exterior environments.
    C
    C.O.P. Coefficient of Performance. Ratio of the rate of heat delivered versus the rate of energy output in consistent units. Or a complete, operating heat pump system operating under design conditions.
    caulking A compound that may have a base of oil, resin, latex or other materials, applied wherever two different materials or parts of the building, such as windows and door frames, meet.
    cooling ton Measure of cooling capacity equal to 12,000 BTU/hr.
    cooling waste heat recovery or process heating An energy conservation system whereby some space heating or water heating is done by actively capturing byproduct heat that would otherwise be ejected into the environment. In nonresidential buildings, sources of waste heat include refrigeration/air-conditioner compressors, manufacturing or other processes, data processing centers, lighting fixtures, ventilation exhaust air, and the occupants themselves.
    D
    degree day A unit that represents one degree of decline from a given point (such as 65oF) in the mean outdoor temperature of one day. Often used in estimating fuel requirements of buildings.
    demand charge The demand charge is based on the highest-demand interval each month.Sometimes also called Billed Demand, Demand Charges are based on a twelve-month historical record of each metered facility.
    duct A pipe or tube through which heated or cooled air flows.
    E
    EER Energy Efficiency Ratio. Ratio used to rate the efficiency of air conditioners.
    electronic funds transfer (EFT) Bill payment through automatic transfer from your bank account to the utility payment account.
    energy The quantity of electricity supplied, measured in kilowatt hours (kWh.)
    energy lifestyle The energy-usage habits of individuals and how they can be improved to use energy wisely and reduce monthly consumption.
    enthalpy control Provides the means to sense outside air temperature and humidity. When these conditions are acceptable fresh air can be used instead of cooling.
    F
    foot-candle A measure of how much light is reaching a given location. Using foot-candles to measure light is akin to using a thermometer to measure temperature.
    fuel Any substance that can be used to produce heat or some other form of energy.
    fuel adjustment charge (FAC) Fuel adjustment or fuel recovery charges are based on the current month's cost of fuel to operate the power generation plants. FACs or FRCs vary from 1¢ - 5¢ per kWh. Because tariff rate schedules are set for the year, if fuel costs have decreased since the rate was set, the charge can appear as a credit on the bill. (also called fuel cost recovery)
    fuel cost recovery (FCR) Fuel adjustment or fuel recovery charges are based on the current month's cost of fuel to operate the power generation plants. FACs or FRCs vary from 1¢ - 5¢ per kWh. Because tariff rate schedules are set for the year, if fuel costs have decreased since the rate was set, the charge can appear as a credit on the bill.
    H
    harmonics Currents from electrical equipment within a facility that can overheat wires and transformers.
    heat exchanger A mechanical device used to transfer heat from one medium to another, such as from water to air.
    heat gain The amount of heat flowing into a home as a result of sunshine, warm air leakage, warming of the walls and roof, and heat given off by people and equipment.
    heat loss The amount of heat in a building that is lost as a result of heat flow through walls, windows, and roof, and air leakage through many parts of the thermal envelope.
    heat pump A year-round space-conditioning system capable of both heating and cooling. A heat pump always delivers more BTUs than are in the electrical energy used to operate it.
    heat pump water heater Single unit that both heats water and provides spot cooling.
    heat recovery unit A device used to capture a portion of the heat expelled from an air conditioning or heat pump compressor. It is used for domestic water heating, in essence providing "free" hot water.
    heat transfer The passage of heat from a warm body to a cooler one.
    heating seasoned performance factor (HSPF) Total heating output of a heat pump during its normal annual usage period for heating, divided by total electric power input during the same period.
    I
    Illuminating Engineering Society of North America (IENSA) The recognized technical authority in the lighting design industry, IENSA has established the guidelines to assure proper lighting design.
    infiltration The undesirable flow of air into a building through cracks around doors, windows and other openings in the building. Infiltration is generally accompanied by exfiltration--flow out of the building.
    K
    kilowatt (kW) A unit for measuring electrical energy. One kilowatt is 1,000 watts and equal to 3,413 BTUs. A kilowatt-hour equals one kilowatt of electrical power taken from an electrical circuit steadily for one hour.
    kilowatt Hour (kWh) Represents the use of 1,000 watts of electricity for one full hour. It is equivalent to 10 100 watt lightbulbs burned simultaneously and continuously for one hour.
    L
    light loss factor LLF is used to create a safety margin to assure adequate lighting over a period of time. Good lighting design requires the designer to allow for the depreciation of the a fixture's light output dues to dirt and age of the equipment. A LLF of 0.80 allows for a 20% degradation in the lighting level.
    load-shifting The ability to change the amount of energy used at any given time. Load shifting can be accomplished by turning off a piece of equipment; switching to internal, off-grid power generation sources; or operation of equipment during off-peak hours.
    load management The process of balancing the supply of electricity on a network with the electrical load by adjusting or controlling the load rather than the power station output.
    lumen A measure of the amount of light given off by the lamp in a light fixture. A fixture with a higher level of lumens gives off more light.
    M
    meter constant The number by which the total kWh in a billing cycle is multiplied to accurately reflect the number of kWh registered on the meter.
    minimum, maximum and average foot-candles Variables used to measure how evenly light is distributed in a given layout. As a rule, the lower the difference between the maximum and the minimum, the better the design. The Average figure is often used to indicate the overall lighting level in a given area. However, this figure inaccurately measures uniformity, since an area with very bright and very dark spots can average the same as an area with much more evenly distributed light.
    O
    occupancy sensor Sensing element that detects movement and controls power supply to the lighting unit.
    off-grade A building that is built with a crawl space between the floor and the ground.
    off-peak Periods of relatively low demand on the utility's electrical system. In general, off-peak times are considered as 7 p.m. - 6 a.m. and weekends.
    on-grade A building that is built on a cement slab directly on the ground.
    on-peak Periods of relative high demand on the utility's electrical system. The highest demand time is usually mid-afternoon on weekdays.
    P
    passive solar The design and siting of a building to maximize the effects of such natural processes as evaporation and heat flow, as opposed to active systems which require mechanical devices.
    peak demand The greatest electricity requirement placed upon the generating equipment of an electric utility during a specified period of time, for instance, one hour. The highest demand time is usually mid-afternoon during the summer months.
    phantom (or vampire) load The amount of energy a device consumes while in standby mode or switched "off."
    plug load The energy consumed by any electric device that’s plugged into a socket.
    Power Factor (Reactive Power Charges) Power factor is a measure of how effectively the current delivered to a motor is converted into useful energy. Reactive Power (kVAR) reflects the extent that current and voltage cycle in phase. The best and most efficient power factor is 100%, which occurs when current and voltage are perfectly in phase. Power Factor is shown as a percentage.
    process heating or cooling waste heat recovery An energy conservation system whereby some space heating or water heating is done by actively capturing byproduct heat that would otherwise be ejected into the environment. In nonresidential buildings, sources of waste heat include refrigeration/air-conditioner compressors, manufacturing or other processes, data processing centers, lighting fixtures, ventilation exhaust air, and the occupants themselves.
    R
    R-value A measure of a substance's resistance to the transfer of heat. The higher the number, the greater the resistance.
    ratchet charges Ratchet charges (also called Demand Charges) are based on your 12 month billing history, and is the demand rate used to calculate your charges. The purpose of Billed Demand charges is to reflect peak seasonal demands. Ratchet charges reflect either the maximum demand during the previous eleven months or the maximum demand during the previous summer months, or 100% of the current month's use — whichever is highest.
    refrigerant A substance, such as Freon, which produces a cooling effect by absorption of heat while expanding or vaporizing.
    retrofit Thermal and/or equipment improvements made to an existing building to increase the structure's energy efficiency.
    S
    seasonal energy efficiency ration (SEER) A measure of the efficiency of an air conditioner or a heat pump, expressed as the ratio of output in BTUs to the energy input in watts.
    space conditioning The artificial heating or cooling of any space.
    summary billing Charges for multiple facilities at different locations which go to a single payee can be aggregated into a single bill, called a Summary Bill.
    T
    therm Measure of gas that contains 100,000 BTUs. As there are approximately 1,000 BTUs per cubic foot of gas, there are approximately 100 cubic feet of gas per therm.
    thermal Using, producing, or caused by heat.
    thermal efficiency As used by the process heating industry, thermal efficiency is a percentage figured by dividing the thermal energy put into the product by the total thermal energy expended by the process.
    thermal envelope The structural parts of a building that enclose the conditioned space and control the heat loss/gain of the building.
    time of use (TOU) rates Lower rates sold on a long-term contract basis to customers with certain load patterns or those who have the flexibility to shift usage to off-peak periods, such as evenings, nights or weekends.
    U
    uniformity A measure of how evenly or "smoothly" the lighting level is spread out over an area. It is expressed as a Uniformity Ratio, where the average foot-candles measure is divided by the minimum foot-candles. The lower this ratio, the better.
    V
    vampire (or phantom) load The amount of energy a device consumes while in standby mode or switched "off."
    vapor barrier A building material that resists the passage of invisible moisture in the air. Barriers are usually plastic film, metallic foil or asphalt-coated felt.
    vent Any opening in a building designed for the flow of air or moisture.
    ventilation The process of supplying or removing air by natural or mechanical means to or from any space. Such air may or may not have been conditioned.
    volt The push that moves electric current through a conductor.
    W
    watt An electrical unit of power or rate of doing work. It is analogous to horsepower or foot-pounds per minute of mechanical power. One horsepower equals 746 watts.
    weather-stripping Foam, metal or rubber strips used to form a seal around windows and doors to reduce infiltration.