Glossary
K-L
Last Updated Monday, July 24, 2000
compiled by Nick Sundt


K, L

K

Kerosene. A type of heating fuel derived by refining crude oil that has a boiling range at atmospheric pressure from 400 degrees to 550 degrees F. (Source: US Department of Energy, 1999a).

Kilovolt-Ampere (kVa). A unit of apparent power, equal to 1,000 volt-amperes; the mathematical product of the volts and amperes in an electrical circuit. (Source: US Department of Energy, 1999a).

Kilowatt (kW). A standard unit of electrical power equal to one thousand watts, or to the energy consumption at a rate of 1000 Joules per second. (Source: US Department of Energy, 1999a).

Kilowatt-hour. A unit or measure of electricity supply or consumption of 1,000 Watts over the period of one hour; equivalent to 3,412 Btu. (Source: US Department of Energy, 1999a).

Kinetic Energy. Energy available as a result of motion that varies directly in proportion to an object's mass and the square of its velocity. (Source: US Department of Energy, 1999a).

Kneewall. A wall usually about 3 to 4 feet high located that is placed in the attic of a home, anchored with plates between the attic floor joists and the roof joist. Sheathing can be attached to these walls to enclose an attic space. (Source: US Department of Energy, 1999a).

Kyoto Protocol. An international agreement struck by 159 nations attend-ing the Third Conference of Parties (COP) to the United Nations Framework Convention on Climate Change (held in December of 1997 in Kyoto, Japan) to reduce world-wide emissions of greenhouse gases. If ratified and put into force, individual countries have committed to reduce their greenhouse gas emissions by a specified amount. See Framework Convention on Climate Change, Conference of Parties. (Source: US Environmental Protection Agency, 1999a)


L

La Nina. A cooling of the equatorial waters in the Pacific Ocean. See El Nino and La Nina Page (Source: National Weather Service, 1999a.)

Lagoon. In wastewater treatment or livestock facilities, a shallow pond used to store wastewater where sunlight and biological activity decompose the waste. (Source: US Department of Energy, 1999a).

Lamp (lighting terminology). The lighting industry uses the term lamp to refer to the source of light, the light bulb itself, not the fixture where the light bulb is located. (Source: Lawrence Berkeley Laboratory, 1999)

Landscaping. Features and vegetation on the outside of or surrounding a building for aesthetics and energy conservation. (Source: US Department of Energy, 1999a).

landfill. Land waste disposal site in which waste is generally spread in thin layers, compacted, and covered with a fresh layer of soil each day.(Source: US Environmental Protection Agency, 1999a)

landfill gas. Gas generated by the natural degrading and decomposition of municipal solid waste by anaerobic microorganisms in sanitary landfills. The gases produced, carbon dioxide and methane, can be collected by a series of low-level pressure wells and can be processed into a medium Btu gas that can be burned to generate steam or electricity. (Source: California Energy Commission, 1999a.)

Langley. A unit or measure of solar radiation; 1 calorie per square meter or 3.69 Btu per square foot. (Source: US Department of Energy, 1999a).

lapse rate. The rapidity with which temperature decreases with altitude. The normal lapse rate is defined to be 3.6 degrees F per 1000 feet change in altitude. The dry adiabatic lapse rate is about 5.5 degrees F per 1000 feet, and the wet adiabatic lapse rate varies between 2 and 5 degrees F per 1000 feet. (Source: Carbon Dioxide Information Analysis Center, 1990a).

latent heat. Energy transferred from the earth's surface to the atmosphere through the evaporation and condensation processes. (Source: Carbon Dioxide Information Analysis Center, 1990a).

Latent Cooling Load. The load created by moisture in the air, including from outside air infiltration and that from indoor sources such as occupants, plants, cooking, showering, etc. (Source: US Department of Energy, 1999a).

Latent Heat. The change in heat content that occurs with a change in phase and without change in temperature. (Source: US Department of Energy, 1999a).

Latent Heat of Vaporization. The quantity of heat produced to change a unit weight of a liquid to vapor with no change in temperature. (Source: US Department of Energy, 1999a).

Law(s) of Thermodynamics. The first law states that energy can not be created or destroyed; the second law states that when a free exchange of heat occurs between two materials, the heat always moves from the warmer to the cooler material. (Source: US Department of Energy, 1999a).

Lead Acid Battery. An electrochemical battery that uses lead and lead oxide for electrodes and sulfuric acid for the electrolyte. (Source: US Department of Energy, 1999a).

leaded gasoline. Gasoline containing tetraethyl lead, an important constituent in antiknock gasoline. Leaded gasoline is no longer sold in the United States. (Source: California Energy Commission, 1999a.)

Leading Edge. In reference to a wind energy conversion system, the area of a turbine blade surface that first comes into contact with the wind. (Source: US Department of Energy, 1999a).

Lethe. A measure of air purity that is equal to one complete air change (in an interior space). (Source: US Department of Energy, 1999a).

Levelized Cost. The present value of the total cost of building and operating a generating plant over its economic life, converted to equal annual payments. Costs are levelized in real dollars (i.e., adjusted to remove the impact of inflation). (Source: US Energy Information Administration, 1997a.)

Levelized Life Cycle Cost. A total life cycle cost divided into equal amounts. (Source: US Department of Energy, 1999a).

Life Cycle Cost. The sum of all the costs both recurring and nonrecurring, related to a product, structure, system, or service during its life span or specified time period. (Source: US Department of Energy, 1999a).

life extension. A term used to describe capital expenses which reduce operating and maintenance costs associated with continued operation of electric utility boilers. Such boilers usually have a 40 year operating life under normal circumstances. (Source: California Energy Commission, 1999a.)

life zone. A climatically-defined class that can be associated with regions of soil and biota with a high uniformity in species composition and environmental adaptation. See Holdridge life zone. (Source: Carbon Dioxide Information Analysis Center, 1990a).

lifeline rates. Rates charged by a utility company for the low income, the disadvantaged and senior citizens. The rates provide a discount for minimum necessary utilities, such as electricity requirements of typically 300 to 400 kilowatt/hours per month. (Source: California Energy Commission, 1999a.)

lifetime (atmospheric). The lifetime of a greenhouse gas refers to the approxi-mate amount of time it would take for the anthropogenic increment to an atmospheric pollutant concentration to return to its natural level (assuming emissions cease) as a result of either being converted to another chemical compound or being taken out of the atmosphere via a sink. This time depends on the pollutantís sources and sinks as well as its reactivity. The lifetime of a pollutant is often considered in conjunction with the mixing of pollu-tants in the atmosphere; a long lifetime will allow the pol-lutant to mix throughout the atmosphere. Average life-times can vary from about a week (e.g., sulfate aerosols) to more than a century (e.g., CFCs, carbon dioxide). See residence time.(Source: US Environmental Protection Agency, 1999a)

light-duty vehicles. Automobiles and light trucks combined.(Source: US Environmental Protection Agency, 1999a)

Light truck. Unless otherwise noted, light trucks are defined in this publication as two-axle, four-tire trucks. The U.S. Bureau of Census classifies all trucks with a gross vehicle weight less than 10,000 pounds as light trucks (See Truck size classifications). (Source: Center for Transportation Analysis, 1999a)

Light Quality. A description of how well people in a lighted space can see to do visual tasks and how visually comfortable they feel in that space. (Source: US Department of Energy, 1999a).

Lignite. The lowest rank of coal, often referred to as brown coal, used almost exclusively as fuel for steam-electric power generation. It is brown- ish- black and has a high inherent moisture content, sometimes as high as 45 percent. The heat content of lignite ranges from 9 to 17 million Btu per short ton on a moist, mineral-matter-free basis. The heat content of lignite consumed in the United States averages 13 million Btu per short ton, on the as-received basis (i.e., containing both inherent moisture and mineral matter).

Line Loss (or Drop). Electrical energy lost due to inherent inefficiencies in an electrical transmission and distribution system under specific conditions. (Source: US Department of Energy, 1999a).

liquefied natural gas (lng). Natural gas converted to liquid form by cooling to a very low temperature.(Source: US Environmental Protection Agency, 1999a)

Liquid-Based Solar Heating System. A solar heating system that uses a liquid as the heat transfer fluid. (Source: US Department of Energy, 1999a).

Liquid-To-Air Heat Exchanger. A heat exchanger that transfers the heat contained in a liquid heat transfer fluid to air. (Source: US Department of Energy, 1999a).

Liquid-To-Liquid Heat Exchanger. A heat exchanger that transfers heat contained in a liquid heat transfer fluid to another liquid. (Source: US Department of Energy, 1999a).

liquefied petroleum gas (lpg). Ethane, ethylene, propane, propylene, normal butane, butylene, and isobutane produced at refineries or natural gas processing plants, including plants that fractionate new natural gas plant liquids. (Source: US Environmental Protection Agency, 1999a)

Lithium-Sulfur Battery. A battery that uses lithium in the negative electrode and a metal sulfide in the positive electrode, and the electrolyte is molten salt; can store large amounts of energy per unit weight. (Source: US Department of Energy, 1999a).

lithosphere. The component of the Earth's surface comprising the rock, soil, and sediments. It is a relatively passive component of the climate system, and its physical characteristics are treated as fixed elements in the determination of climate. (Source: Carbon Dioxide Information Analysis Center, 1990a).

litter. Undecomposed plant residues on the soil surface. (Source: Carbon Dioxide Information Analysis Center, 1990a).

Little Ice Age. A cold period that lasted from about A.D. 1550 to about A.D. 1850 in Europe, North America, and Asia. This period was marked by rapid expansion of mountain glaciers, especially in the Alps, Norway, Ireland, and Alaska. There were three maxima, beginning about 1650, about 1770, and 1850, each separated by slight warming intervals. (Source: Carbon Dioxide Information Analysis Center, 1990a).

Live Steam. Steam available directly from a boiler under full pressure. (Source: US Department of Energy, 1999a).

LNG (liquefied natural gas). Natural gas that has been condensed to a liquid, typically by cryogenically cooling the gas to minus 327.2 degrees Fahrenheit (below zero). (Source: California Energy Commission, 1999a.)

longwave radiation. The radiation emitted in the spectral wavelength greater than 4 micrometers corresponding to the radiation emit-ted from the Earth and atmosphere. It is sometimes referred to as terrestrial radiation or infrared radiation, although somewhat imprecisely. See infrared radiation.(Source: US Environmental Protection Agency, 1999a)

low emission vehicle (lev). A vehicle meeting the low-emission vehicle standards. (Source: US Environmental Protection Agency, 1999a)

lower heating value. Quantity of heat liberated by the complete combustion of a unit volume or weight of a fuel assuming that the produced water remains as a vapor and the heat of the vapor is not recovered; also known as net calorific value. See higher heating value.(Source: US Environmental Protection Agency, 1999a)

LPG (liquefied petroleum gas). A mixture of gaseous hydrocarbons, mainly propane and butane that change into liquid form under moderate pressure. LPG or propane is commonly used as a fuel for rural homes for space and water heating, as a fuel for barbecues and recreational vehicles, and as a transportation fuel. It is normally created as a by-product of petroleum refining and from natural gas production. (Source: California Energy Commission, 1999a.)

Load. The demand on an energy producing system; the energy consumption or requirement of a piece or group of equipment. (Source: US Department of Energy, 1999a).

load centers. A geographical area where large amounts of power are drawn by end-users. (Source: California Energy Commission, 1999a.)

Load Factor. The ratio of average energy demand (load) to maximum demand (peak load) during a specific period. (Source: US Department of Energy, 1999a).

Load Forecast. An estimate of power demand at some future period. (Source: US Department of Energy, 1999a).

Load Leveling. The deferment of certain loads to limit electrical power demand, or the production of energy during off-peak periods for storage and use during peak demand periods. (Source: US Department of Energy, 1999a).

Load Management. To influence the demand on a power source. (Source: US Department of Energy, 1999a).

Load Profile or Shape. A curve on a chart showing power (kW) supplied (on the horizontal axis) plotted against time of occurrence (on the vertical axis) to illustrate the variance in a load in a specified time period. (Source: US Department of Energy, 1999a).

Load Shedding. Turning off or disconnecting loads to limit peak demand. (Source: US Department of Energy, 1999a).

Load Shifting. A load management objective that moves loads from on-peak periods to off-peak periods. (Source: US Department of Energy, 1999a).

Local Solar Time. A system of astronomical time in which the sun crosses the true north-south meridian at 12 noon, and which differs from local time according to longitude, time zone, and equation of time. (Source: US Department of Energy, 1999a).

loess. A buff-colored, wind-blown deposit of fine silt, which is frequently exposed in bluffs with steep faces. The thickness can range from 6 to 30 meters. The loess of the USA and Europe is thought to be the fine materials first transported and deposited by the waters of melting ice sheets during the glacial period. It was later blown considerable distances with, in some cases, deposition in lakes. The origin of Asiatic loess, however, is apparently wind-blown dust from central Asian deserts. (Source: Carbon Dioxide Information Analysis Center, 1990a).

Long Ton. A unit that equals 20 long hundredweight or 2,240 pounds. Used mainly in England. (Source: US Department of Energy, 1999a).

Long-Wave Radiation. Infrared or radiant heat. (Source: US Department of Energy, 1999a).

longwave radiation. The radiation emitted in the spectral wavelength greater than 4 micrometers corresponding to the radiation emitted from the Earth and atmosphere. It is sometimes referred to as terrestrial radiation or infrared radiation, although somewhat imprecisely. (Source: Carbon Dioxide Information Analysis Center, 1990a).

Loose Fill Insulation. Insulation made from rockwool fibers, fiberglass, cellulose fiber, vermiculite or perlite minerals, and composed of loose fibers or granules can be applied by pouring directly from the bag or with a blower. (Source: US Department of Energy, 1999a).

Losses (Energy). A general term applied to the energy that is converted to a form that can not be effectively used (lost) during the operation of an energy producing, conducting, or consuming system. (Source: US Department of Energy, 1999a).

Loss of Load Probability (LOLP). A measure of the probability that a system demand will exceed capacity during a given period; often expressed as the estimated number of days over a long period, frequently 10 years or the life of the system. (Source: US Department of Energy, 1999a).

Low Btu Gas. A fuel gas with a heating value between 90 and 200 Btu per cubic foot. (Source: US Department of Energy, 1999a).

Low-E glazing (window efficiency Terminology). A special window coating that helps prevent the warmth inside your house from escaping through the glass in the winter (pyrolitic). A variation (solar control) is designed to block heat from the summer sun. Low-E coating can reduce energy use by up to 35 percent. (Source: Lawrence Berkeley Laboratory, 1999)

Low Emission Vehicle (LEV). a vehicle certified by the California Air Resources Board to have emissions from zero to 50,000 miles no higher than 0.075 grams/mile (g/mi) of non-methane organic gases, 3.4 g/mi of carbon monoxide, and 0.2 g/mi of nitrogen oxides. Emissions from 50,000 to 100,000 miles may be slightly higher. (Source: California Energy Commission, 1999a.)

Lower (Net) Heating Value. The lower or net heat of combustion for a fuel that assumes that all products of combustion are in a gaseous state. (See Net Heating Value below.) (Source: US Department of Energy, 1999a).

Low-Flow Solar Water Heating Systems. The flow rate in these systems is 1/8 to 1/5 the rate of most solar water heating systems. The low-flow systems take advantage of stratification in the storage tank and theoretically allows for the use of smaller diameter piping to and from the collector and a smaller pump. (Source: US Department of Energy, 1999a).

Low Flush Toilet. A toilet that uses less water than a standard one during flushing, for the purpose of conserving water resources. (Source: US Department of Energy, 1999a).

Low-Pressure Sodium Lamp. A type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0.13 to 1.3 Pascal. The yellow light and large size make them applicable to lighting streets and parking lots. (Source: US Department of Energy, 1999a).

Lumen. An empirical measure of the quantity of light. It is based upon the spectral sensitivity of the photosensors in the human eye under high (daytime) light levels. Photometrically it is the luminous flux emitted with a solid angle (1 steradian) by a point source having a uniform luminous intensity of 1 candela. (Source: US Department of Energy, 1999a).

Lumens/Watt (lpw). A measure of the efficacy (efficiency) of lamps. It indicates the amount of light (lumens) emitted by the lamp for each unit of electrical power (Watts) used. (Source: US Department of Energy, 1999a).

Luminaire. A complete lighting unit consisting of a lamp(s), housing, and connection to the power circuit. (Source: US Department of Energy, 1999a).

Luminance. The physical measure of the subjective sensation of brightness; measured in lumens. (Source: US Department of Energy, 1999a).

Lux. The unit of illuminance equivalent to 1 lumen per quare meter. (Source: US Department of Energy, 1999a).