Natural Gas and Energy Efficiency Terminology Guide
October 2, 2008
The following is a glossary of terms associated with energy efficiency and the natural gas industry. Industry terminology was compiled with help from the following sources:
Energy Solutions Center, American Gas Association, The Encyclopedia of Alternative Energy and Sustainable Living, The U.S. Green Building Council, The Building Commissioning Association, U.S. Department of Energy & Engineering Toolbox.com.
This Glossary was produced by Summer Lewis & Partners on behalf of the Energy Solutions Center Inc
Energy Unit Calculator
Absolute Open Flow (AOF) – The number of cubic feet of gas per 24 hours that would be produced by a well if the only pressure against the face of the producing sand in the well bore were atmospheric pressure.
Absorbent – A material which, due to an affinity for certain substances, extracts one or more such substances from a liquid or gaseous medium with which it contacts, and which changes physically, or during the process.
Absorption – The extraction of one or more components from a mixture of gases when gases and liquids are brought into contact. The assimilation or extraction process causes (or is accompanied by) a physical or chemical change, or both, in the sorbent material.
Absorption Chiller – A type of air cooling device that uses absorption cooling to cool interior spaces. The key feature of absorption cooling equipment is that it produces cooling by using heat energy as an input, rather than by using mechanical energy. For this reason, absorption chillers are often common in facilities that had large boiler plants with excess capacity during the cooling season.
Absorption Chilling – A process in which cooling of an interior space is accomplished by the evaporation of a volatile fluid, which is then absorbed in a strong solution, then desorbed under pressure by a heat source, and then recondensed at a temperature high enough that the heat of condensation can be rejected to a exterior space.
Absorption cooling is essentially an air conditioner driven not by electricity, but by a heat source such as natural gas, propane, solar-heated water, or geothermal-heated water. Because natural gas is the most common heat source for absorption cooling, it is also referred to as gas-fired cooling. Although mainly used in industrial or commercial settings, absorption coolers are now commercially available for large residential homes.
Absorption Plant – A device that removes hydrocarbon compounds from natural gas, especially casing head gas. The gas is run through oil of proper character, which absorbs the liquid constituents, which are then recovered by distillation. Note: absorption plants can also be chiller plants with absorption chillers in place.
Absorption Type Air Conditioner, Direct Fired – A self-contained device whichprovides cooling by direct application of heat in the form of hot water, steam
or exhaust gas. Direct fired are gas or oil run.
Accelerated Cost Recovery System (ACRS) – A depreciation system enacted as part of the Economic Recovery Tax Act of 1981 that allows rapid depreciation
of assets for tax purposes. It was repealed in the Tax Reform Act of 1986.
Acceptance Test – An investigation performed on an individual lot of a previously qualified product (e.g., plastic pipe) by, or under the observation of, the purchaser to establish conformity with a purchase agreement stipulating specified requirements.
Acetone Test – A process control test for PVC pipe which indicates how well the rigid vinyl compound has been fused together in the extruder. Improperly fused pipe will tend to flake when placed in anhydrous acetone.
Achievable Potential – In DSM (demand side management), an estimate of energy savings based on the assumption that all energy-efficient options will be adopted to the extent that they are cost-effective and possible through utility DSM (demand side management) programs.
Active Solar Energy System – A solar water or space-heating system that uses pumps or fans to circulate the fluid from the solar collectors to a storage tank subsystem. There are two basic types of active solar heating systems based on the type of fluid – either liquid or air – that is heated in the solar energy collectors. Liquid-based systems heat water or an antifreeze solution in a “hydronic” collector, whereas air-based systems heat air in an air collector.
<![if !supportLineBreakNewLine]> <![endif]>Both systems collect and absorb solar radiation, then transfer the solar heat directly to the interior space or to a torage system, from which the heat is distributed. If the system cannot provide adequate space heating, an auxiliary or back-up system provides the additional eat. Liquid systems are more often used when storage is included, and are well suited for radiant heating systems, boilers with hot water radiators, and even bsorption heat pumps and coolers. Both air and liquid systems can supplement forced air systems.
Adiabatic – A term indicating that no heat is lost or gained by a material being subjected to a thermodynamic process. An adiabatic process is one in which there is no exchange of heat with the surroundings.
Adsorption – The extraction from a mixture of gases or liquids of one or more components, by surface adhesion to that material with which the gases or liquids come in contact. The adsorption or extraction process does not cause and is not accompanied by either a physical or chemical change in the sorbent material.
Advances for Construction – A deferred credit account representing cash advances paid to the utility by customers requiring the construction of facilities in their behalf. These advances are refundable — the time or extent of refund is dependent on the contract provisions of the advance (usually dependent on whether or not during a specified period the revenue from the installation warrants the refund). The unrefunded balance, if any, must be transferred to the appropriate plant account.
Air Conditioner, Room – A factory-made encasedassembly, designed as a unit for mounting in a window, through a wall, or as aconsole, for the purpose of delivering conditioned air to an enclosed space without ducts.
Air Conditioning – The
process of heating, cooling, humidifying, filtering, drying, deodorizing, or
otherwise treating air in a room or building to maintain a specified
temperature and/or relative humidity and to remove impurities.
Air Conditioning, Central – A mechanical system that is designed to provide air conditioning, which may include cooling, heating, dehumidifying, circulation and cleaning. The air is treated by the conditioner at one or more central locations outside the space served and conveyed to and from the space by means of fans and pumps through ducts and pipes.
Air Handler – An air handler, or air handling unit (often abbreviated to AHU), is a device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. Usually, an air handler contains a blower, heating and/or cooling elements, filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductwork that distributes the conditioned air through the building, and returns it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served, without ductwork.
Air Pollutants (from fossil fuel) – Carbon Dioxide, Nitrous Oxides, Sulfur oxides, Particulates, and VOC’s are by products of burning fossil fuels, and are health and environmental hazards when release in great quantities.
Air-Source Heat Pump – A heat pump that transfers heat from outdoor air to indoor air during the heating season, and works in reverse during the cooling season. Air-source heat pumps are efficient heating and cooling sources, especially in warm climates.
Allocation-Capacity – A process by which capacity available in a pipeline is distributed to parties in the event requests for volume (i.e., nominations) are in excess of the available space. Typically the allocation is based on service type, contract type and a company’s tariff provisions.
Allowance for Funds Used During Construction (AFUDC) – AFUDC is a component of construction costs representing net cost of borrowed funds and a reasonablerate on other funds used during the period of construction. AFUDC is capitalized until the project is placed in operation by concurrent credits to the income statement and charges to utility plant, based generally on the amount expended to date on the particular project. Effective January 1, 1977, FERC amended the Uniform System of Accounts establishing formulas for maximum allowable AFUDC rates.
Allowed Rate of Return – The rate of return that a regulatory commission allows on a rate base in establishing just and reasonable rates for a utility. It is usually based on the composite cost of financing rate base from debt, preferred stock, and common equity.
Ambient Vaporizer – A vaporizer which derives energy for vaporizing and heating LNG from storage conditions to send out conditions from naturally occurring sources such as the atmosphere, sea water, or geothermal waters.
American National Standards Institute (ANSI) – The coordinating organization for America’s federated national standards system. The ANSI federation consists of nine hundred companies, large and small, and some two hundred trade, technical, professional, labor, and consumer organizations.
American National Standards Institute X12 Committee – The committee sanctioned by ANSI for developing and maintaining U.S. standards for business-to-business electronic data interchange pertaining to trade transactions, with business-to-business defined broadly to include all organizations but excluding all individual consumers.
Annual Fuel Utilization Efficiency (AFUE) – AFUE measures average annual seasonal efficiency of a gas furnace or boiler and may be expressed as total heating output divided by total energy (fuel) input.
Associated Liquids – Condensates (liquid hydrocarbons without free water) produced in conjunction with the production of gas to be transported or liquefiable hydrocarbons contained in such gas, but not including oil.
Avoided Cost – The incremental cost that a utility would incur to purchase or produce an amount of gas equivalent to that saved by a DSM (demand side management) measure. Components may include energy, capacity, storage, transmission and distribution. Avoided costs are generally used to represent the benefits of utility-sponsored DSM (demand side management) programs.
Back Pressure – Pressure against which a fluid is flowing. May be composed of friction in pipes, restrictions in pipes, valves, pressure in vessels to which fluid is flowing, hydrostatic head, or other resistance to fluid flow.
Backhaul – A transaction that results in the transportation of gas in a direction opposite of the aggregate physical flow of gas in the pipeline. This is typically
achieved when the transporting pipeline redelivers gas at a point(s) upstream from the point(s) of receipt. A backhaul condition will exist as long as the aggregate backhaul transactions total less than the aggregate forward haul transactions. A backhaul transaction can result in a delivery by non-delivery or cut back (reduction) of physical flow at a delivery point.
<![endif]>Baffles – Plates, louvers, or screens placed in the path of fluid flow to cause change in the direction of flow; these are used to promote mixing of gases or to eliminate undesirable solid or liquid particles in the fluid stream. Sometimes baffles are inserted in a flue to lengthen the travel of flue gases and increase efficiency of operation.
Barrel (Oil) – A volumetric unit of measurement equivalent to 42 U.S. gallons, 9,702 cubic inches, 5.6146 cubic feet, 34.9722 Canadian Imperial gallons, 158.99 liters, or .15899 cubic meters. It is the unit of measurement commonly used to measure oil production and oil reserves within the U.S.
Base Pressure – The pressure used as a standard in determining gas volume. Volumes are measured at operating pressures and then corrected to base pressure volume. Base pressure is normally defined in any gas measurement contract. The standard value for natural gas in the United States is 14.73 psia, established by the American National Standards Institute as standard Z-132.1 in 1969.
Basic Air or Gas Time – The time required to pass one cubic foot of air or gas through a given orifice in a flow prover at stated base conditions. This time is stamped on the prover orifice in seconds.
Best Available Control Technology (BACT) – A concept taken from the Clean Air Act designed to preserve air quality from degradation by requiring
facilities in some instances be controlled to the extent possible using the best available technology.
Boiler, High Pressure – A boiler furnishing hot water at pressures in excess of 160 pounds per square inch (psi) and at temperatures in excess of 250oF (121oC) or steam at pressures in excess of 15 psi.
Boiler, Low Pressure – A boiler furnishing hot water at pressures not exceeding 160 pounds per square inch (psi) and at temperatures not more than 250oF (121oC) or steam at pressures not more than 15 psi.
Btu, Dry – Heating value contained in cubic foot of natural gas measured and calculated free of moisture content. Contractually, dry may be defined as less than or equal to seven pounds of water per Mcf.
Building Commissioning – Building commissioning provides documented confirmation that building systems function according to criteria set forth in the project documents to satisfy the owner’s operational needs. Commissioning existing systems may require developing new functional criteria to address the owner’s current requirements for system performance.
Commissioning for Existing Buildings (sometimes referred to as retro-commissioning) is a systematic
process for investigating, analyzing, and optimizing the performance of building systems by improving their operation and maintenance to ensure their continued performance over time. This process helps make the building systems perform interactively to meet the owner’s current facility requirements.
Burner, Conversion – A burner designed to supply gaseous fuel to an appliance originally designed to utilize another fuel. a. Firing Door Type – a conversion burner designed specifically for boiler or furnace firing door installation. b. Inshot Type – a conversion burner normally designed for boiler or furnace ash pit installation and fired in a horizontal position. c. Upshot Type – a conversion burner normally designed for boiler or furnace ash pit installation and fired in a vertical position at approximately grate level.
Burner, Gas – A device for the final release of air/gas, or oxygen/gas mixtures, or air and gas separately into the combustion zone. Gas burners may be classed as atmospheric burners or blast (pressure) burners.
Calibrate – To ascertain, usually by comparison with a standard, the locations at which scale or chart graduations should be placed to correspond to a series of values of the quantity which the instrument is to measure, receive or transmit. Also, to adjust the output of a device, to bring it to a desired value, within aspecified tolerance for a particular value of the input. Also, to ascertain the error in the output of a device by checking it against a standard.
Carbon/Hydrogen Ratio – The ratio, either on a weight or on a molecular basis, of carbon-to-hydrogen in a hydrocarbon material. Materials with a high carbon/hydrogen ratio (e.g., coal) are solid. The ratio is useful as a preliminary indication of the hydrogen quantity needed toconvert the hydrocarbon to a gas and/or liquid.
Class of Service – Defines the type of customer. The common classes of service applied to ultimate consumers, and considerably more completely described in the A.G.A. publication “Definitions of a Gas Customer and Classes of Service for IndustryReporting Purposes”, are: 1.Residential Service: Covers service to
customers for domestic purposes (single, multifamily, or mobile homes, etc.). In residential service, the number of housing units within a structure determines the customer classification. 2.Commercial Service: Covers service to customers engaged in wholesale or retail trade, agriculture, communications, finance, fisheries, forestry, government, insurance, real estate, transportation, etc., and to customers not directly involved in other classes ofservice. 3.Industrial Service: Covers service to customers engaged primarily in a process which either involves the extraction of raw materials from the earth or a change of raw unfinished materials into another form or product.
Classification of Costs – A two step process to take functionalized costs and (1) determine whether they are fixed or variable and then (2) determine whether the fixed costs will be recovered through the demand rate or the commodity rate.
Climate Change – A change in the “average weather” that a region experiences. Average weather includes all the features associated with weather such as temperature, wind patterns and precipitation. A natural system known as the greenhouse effect regulates the temperature
on Earth. Human activities have the potential to disrupt the balance of this systemby increasing the amount of heat-trapping gases in the atmosphere which enhances the warming capability of the natural greenhouse effect.
Coal Gasification – Acontrolled process of reacting coal, steam, and oxygen under pressure and
elevated temperature. The crude gas is purified and has a low heating value. Subsequent catalytic upgrading can be employed to produce high-Btu pipeline grade gas.
Coefficient of Heat Transmission (U-Value) – A value that describes the ability of a material to conduct heat. The number of
BTU that flow through one square foot of material in one hour. It is the reciprocal of the R-value (i.e. U-value = 1/R-value). The lower the number, the greater the heat transfer resistance (insulating)characteristics of the material.
Coefficient of Performance (COP) – A ratio of the work or useful energy outputof a system versus the amount of work or energy put in to the system as
determined by using the same energy equivalents for energy in and out. COP is used as a measure of the steady state performance or energy efficiency of heating, cooling, and refrigeration appliances. It is equal to the energy efficiency ratio (EER) divided by 3.412. The higher the COP, the more efficient the device.
Cogeneration – The use of a single prime fuel source in a reciprocating engine or gas turbine to
generate electrical and thermal energy in order to optimize the efficiency of the fuel used. The dominant demand for energy can be either electrical or
thermal. Usually it is the latter with excess electrical energy, if any, being transmitted into the local power supply company’s lines (with a reciprocal
situation existing when electrical demands exceed the cogeneration plant’s output). A parallel exists with total energy plants, which are typically
designed for the electrical demands rather than thermal. Under the 1978 Public Utility Regulatory Policies Act (PURPA), regulated utilities are required to
purchase electricity furnished by cogenerators and small power producers at rates set by regulatory bodies having jurisdiction over the utility receiving the electricity based on “full avoided cost.”
Combination Utility – Utility which supplies both gas and some other utility service (electricity, water, etc.). For purposes of A.G.A. statistics, a combination utility derives at least 5 percent but less than 95 percent of its total operating revenues from gas operation.
Combined Accounts – When two or more meters are combined for billing purposes under the following conditions: Where combinations of meter readings are specifically provided for in rate schedules. Where the maintenance of adequate service and/or where a company’soperating convenience shall require the installation.
Combined-Cycle – In a combined cycle power plant the hot exhaust gas of a gas or oil fired gas turbine is utilized to
generate steam in a separate water / steam cycle. The hot steam is expanded in a steam turbine providing power to drive a generator. The combination of gas and steam turbine cycles allows electric power generation with highest efficiency.
Combo Heater – A
single gas appliance that provides both space heating and domestic hot water. These systems are designed primarily for use as a forced air heating system, but can also be adapted for new hydronic baseboard installations.
Combustible Material – Combustible material, as pertaining to material adjacent to or in contact with heat producing appliances, chimney connectors and vent connectors, steam and hot water pipes, and warm air ducts, means material made of or surfaced with wood, compressed paper, plant fibers, or other material that will ignite and burn. Such material shall be considered as combustible even though flame proofed, fire retardant treated, or plastered.
Compact Fluorescent Lamp (CFL) – Lamps that combine the energy efficiency of fluorescent lighting with the convenience and popularity of incandescent fixtures. CFLs can replace incandescents that are roughly 3–4 times their wattage, saving up to 75% of the initial lighting
energy. Although CFLs cost more than comparable incandescent bulbs, they last 10–15 times as long.
Conditional Demand Analysis – A method that is used to estimate equipment-specific energy consumption, without requiring end-use metered data for the appliances. Instead, it relies on the statistical analysis of consumption data, appliance saturation data, and other data such as demographic, household, weather, economic and market data.
Conduction, Thermal – Process of heat transfer through a material medium in which kinetic energy is transmitted by the particles of the material from particle to particle without gross displacement of the particles.
Contract Demand (CD) – The amount of the system’s capacity to deliver gas which a natural gas pipeline or distributor agrees to reserve for a particular customer and for which the customer agrees to pay ademand charge as specified in the applicable tariff. Also, the daily quantity of gas which asupplier agrees to furnish and for which the buyer agrees to pay, under a specific contract.
Control, Limit – An automatic safety control responsive to changes in level, pressure, or temperature and normally set beyond the operating range for limiting the operation of the controlled equipment.
Control, Operating – A control other than a safety control or interlock, to start or regulate burner firing according to load demand and to stop or regulate fire on satisfaction of demand or upon reaching normal temperature or pressure in the device being fired. Operating controls may also actuate auxiliary equipment.
Convector – An agency of convection. In heat transfer, a surface designed to transfer its heat to a surrounding fluid largely or wholly by convection. The heated fluid may be moved mechanically or by gravity (gravity convector). Such a surface may or may not be enclosed or concealed.
Conversion to Natural Gas – Changing the gas service to ultimate customers from a fuel other than natural gas to natural gas, including
adjustment of consumers’ appliances to perform satisfactorily with natural gas. Natural gas does not necessarily mean straight natural gas; stabilizing the heat content of the sendout gas by diluent gases or enriching gases is not considered to change the basic character of natural gas. For the purpose of uniform reporting, a company should be considered a natural gas company when 95 percent of the system has been converted.
Critical Temperature and Pressure – That temperature above which a gas cannot be liquefied by pressure alone. The pressure under which a substance may exist as a gas in equilibrium with the liquid at the critical temperature is the critical pressure.
De-Coupling – In public utility regulation, decoupling refers to the disassociation of a utility profit’s from its sales of the energy commodity. Instead, a rate of return is aligned with meeting revenue targets, and rates are trued up or down to meet the target at the end of the adjustment period. This makes efficiency and distributed generation to operate within the utility environment.
Degree Day, Cooling – A measure of the need for air conditioning (cooling) based on temperature and humidity. Although cooling degree days are published for many weather stations, a specific procedure has not been generally accepted.
Dehumidifier – An appliance that reduces the humidity in a room by condensing moisture in the air on to a cold surface. A dehumidifier works in a similar way to an air conditioner, the main difference being that it has both its hot and cold coils in the same box. Air is drawn in by a fan and moisture from the air condenses on one set of coils much like an air conditioners evaporator coils. The water drips into a removable bucket or through a hose to a drain. The other coil warms the air, which is blown back into the room.
Demand – The rate at which gas is delivered to or by a system, part of a system, or a piece of equipment, expressed in cubic feet or therms or multiples thereof, for a designated period of time called the demand interval. Note: the electric industry also measures demand for electricity.
Demand Day – The 24-hour period specified by a supplier-user contract for purposes of determining the purchaser’s daily quantity of gas used (e.g., 8 AM to 8 AM, etc.). This term is primarily used in pipeline-distribution company agreements. It is similar to, and usually coincides with, the distribution company “sendout day”.
Demand, Integrated – The demand averaged over a specified period, usually determined by an integrating demand meter or by the integration of a load curve. It is the average of the instantaneous demands during a specified demand interval.
Demand Side Management (DSM) – Also known as energy demand management, entails actions that influence the quantity or patterns of use of energy consumed by end users, such as actions targeting reduction of peak demand during periods when energy-supply systems are constrained. Peak demand management does not necessarily decrease total energy consumption but could be expected to reduce the need for investments in networks and/or plants.
Department of Energy (U.S.DOE) – The Department of Energy is the twelfth Cabinet Position, and it consists of the Office of the Secretary of Energy and the Federal Energy Regulatory Commission. It was created on August 4, 1977 as a result of the Department of Energy Organization Act of 1977. There are many subdivisions within the DOE, but the Economic Regulatory Administration and Energy Information Administration are two groups which have significant bearing on gas utility operations.
Depreciation – Return of investment through inclusion in cost of service (and rates) of a pro rata part of the cost of property, calculated to spread the total investment cost over a certain period of time or number of units that measure the useful life of the investment. Depreciation (in the Code of Federal Regulations) is to reimburse the company for “…the loss in service value not restored by current maintenance, incurred in connection with the consumption or prospective retirement of gas plant in the course of service from causes which are known to be in current operation and against which the utility is not protected by insurance. Among the causes to be given consideration are wear and tear, decay, action of the elements, inadequacy, obsolescence, changes in the art, changes in demand and requirements of public authorities, and, in the case of a natural gas company, the exhaustion of natural resources.”
Desiccant Cooling – A new and potentially clean technology that can be used to condition the internal environment of buildings without the use of harmful refrigerants. Unlike conventional air conditioning systems, which rely on electrical energy to drive the cooling cycle, desiccant cooling is an open heat driven cycle, which uses a desiccant wheel and cooling coil in tandem to achieve both cooling and dehumidification. Because it is a heat driven cycle, there is the potential to use environmentally cleaner sources of energy such as gas, hot water, waste heat or any heat source, including solar thermal energy, able to elevate the air temperature to a level adequate for reactivation.
Desiccant materials, which absorb moisture, can be dried, or regenerated, by adding heat supplied by natural gas, waste heat, or the sun. In most systems, a wheel that contains a desiccant turns slowly to pick up humidity from incoming air and discharge that humidity to the outdoors. Desiccant cooling can also be used in tandem with conventional air conditioning system in which the desiccant removes humidity and the AC system provides cooling, and in energy recovery ventilators (ERV) to dehumidify incoming fresh air in the summer.
Differential Pressure – The pressure difference between two points in a system. For example, the difference in pressure between the upstream and downstream taps of an orifice plate, used to measure volume passing through the orifice.
Direct Water Heater – A type of water heater in which heated water is stored within the tank. Hot water is released from the top of the tank when a hot water faucet is turned. This water is replaced with cold water that flows into the tank and down to just above the bottom plate under which are the burners.
Distribution – The act or process of distributing gas from the city gas or plant that portion of utility plant used for the purpose of delivering gas from the city gate or plant to the consumers, or to expenses relating to the operating and maintenance of distribution plant.
Draft Hood – A device built into an appliance, or made a part of the flue or vent connectorfrom an appliance, which is designed to (a) assure the ready escape of the products of combustion from the combustion chamber in the event of no draft, back draft, or stoppage beyond the draft hood; (b) prevent a back draft from entering the combustion chamber of the appliance; and (c) neutralize the effect of stack action of the chimney or gas vent upon the operation of the appliance.
Economic Potential – In DSM (demand side management), an estimate of energy savings based on the assumption that all energy-efficient options will be adopted and all existing equipment will be replaced with the most efficient measure possible whenever it is cost-effective to do so, without regard to market acceptance.
Economic Regulatory Administration (ERA) – Formerly the agency in the Department of Energy charged with the responsibility for imports of natural gas. In 1989, the ERA was eliminated and its functions were transferred to the Office of Fossil Energy (FE) in the Department of Energy.
Economizer – An arrangement of tubes through which the feed water passes before entering boiler drum and flue gases leave burners. Economizers are invariably counter flow; meaning the water flows opposite to the gases, and heat of gases is transferred to the water.
Energy Efficiency Ratio (EER) – A ratio calculated by dividing the cooling capacity in Btu per hour by the power input in watts at any given set of rating conditions. Heating Seasonal Performance Factor (HSPF) – the total heating output of a heat pump during its normal annual usage period for heating divided by the total electric power input in watt-hours during the same period. Seasonal Energy Efficiency Ratio (SEER) – the total cooling capacity of a central unitary air conditioner or unitary heat pump in Btu’s during its normal annual usage period for coolingdivided by the total electric energy input in watt-hours during the same period.
EnergyGuide – Almost all home appliances, including refrigerators, dishwashers and laundry units, display a prominent yellow-and-black EnergyGuide. The label was developed by the Federal Trade Commission. The largest number on the guide states the estimated annual operating cost of the appliance. Some equipment, such as ovens or clothes dryers, may have two large numbers – one for electric, one for natural gas. One of the most helpful features of the EnergyGuide is a sliding scale that compares the appliance to other models and brands.
ENERGYSTAR – The ENERGYSTAR logo identifies appliances as being among the most energy-efficient products in their classes. Theyusually excee minimum federal energy-use standards by a significant amount. TheEnergySta designation, developed by the U.S. Environmental Protection Agency and Department of Energy, can be found on thousands of products, ncluding windows, water heaters, furnaces, air conditioners, light bulbs, computers and more.
Energy Audit – A review of a customer’s energy usage, often including recommendations to alter the customer’s demand or reduce energy usage. An audit normally involves a visit to the customer’s facility.
Energy Efficiency Program – A program aimed at reducing overall consumption, often without regard for the timing of the program-induced savings. Such savings are generally achieved by substituting technically more efficient equipment to produce the same level of end-use services with less energy.
Solutions Center- The Energy Solutions Center is a technology commercialization and market development organization representing energy utilities, municipal energy authorities, and equipment manufacturers and endors. The mission of the Center is to accelerate the acceptance of and deployment of new energy-efficient, gas-fueled technologies that enhance the operations and productivity of commercial and industrial energy users, and improves comfort and reliability for residential energy users.
Engine Driven Generator – A power generator that incorporates an engine and a generator driven by the engine. The generator incorporates a sound insulation cover that allows for efficient cooling of the various internal components. A fan draws in cooling air through one or more cooling air vents to cool a battery, a DC/DC converter, an electronic module, the engine, the generator, and the muffler. The insulation cover provides quiet operation and efficient cooling of the engine-driven generator.
Environmental Protection Agency (EPA) – A federal agency created in 1970 to permit coordinated and effective governmental action, for protection of the environment by the systematic abatement and control of pollution, through integration of research monitoring, standard setting, and enforcement activities.
Evaporative Cooling – The adiabatic exchange of heat between air and a water spray or wetted surface. The water approaches the wet bulb temperature of the air, which remains constant during its traverse of the exchanger.
Evaporator – Equipment or device that extracts or drives out vapors from liquid solutions or gases. Also, equipment that is part of refrigerating systems to permit liquid refrigerants to evaporate in the process of absorbing heat.
Exchange Transactions – In a gas exchange between two parties, gas is received from (or delivered to) the first party in exchange for gas delivered to (or received from) the second party. An exchange provides ameans for delivering gas supplies to a customer without the necessity o constructing and operating duplicative facilities. Central to the concept of an exchange is mutual benefits to the two parties engaging in the exchange. The transaction must involve reciprocal benefit or the trade of comparable values.
Exterior Zones – The portions of a building, with significant amounts of exterior walls, windows, roofs, or exposed floors. Such zones have heating or cooling needs largely dependent upon weather conditions.
Federal Energy Regulatory Commission (FERC) – An agency of the government of the United States created by an Act of Congress, the Department of Energy Federal Power Commission’s interstate regulatory functions over the electric power and natural gas industries. The Act also transferred from the Interstate Commerce Commission the authority to set oil pipeline transportation rates and to set the value of oil pipelines for ratemaking purposes. In 1978, Congress passed the Natural Energy Act, broadening the FERC’s jurisdiction and
regulatory functions. The FERC now also regulates producer sales of natural gas in intrastate commerce. The FERC establishes uniform ceiling prices for each of several categories of natural gas, and these prices apply to all sales on a nationwide basis.
Federal Power Commission – An agency of the government of the United States created by an Act of Congress, the Federal Water Power Act, in 1920. Originally charged with regulating the nation’s water resources, the FPC later assumed responsibility for regulating the electric power and natural gas industries that sell or transport electricity or gas for resale in interstate commerce. With respect to the gas industry, the general regulatory principles of the FPC were defined in the Natural Gas Act, as amended. In 1977, the FPC passed into history and the Department of Energy was created, incorporating the independent regulatory agency known as the Federal Energy Regulatory Commission.
Fin Fan Cooler – A dry cooler that passes cooling air over finned tubes, through which some hot fluid is being passed, during the cooling process. A fan is used to create movement of air over the finned tubes. Air movement is regulated in a number of ways, the most common being a variable speed fan.
Flash Back – The burning of gas in the mixing chamber of a burner or in a piping system, usually due to an excess of primary air or too low a velocity of the combustible mixture through the burner part.
Fuel Gas – A quantity of gas required by a transporter to provide the transportation service. Fuel gas includes, but is not limited to, gas consumed intransporter’s mainline compressor stations,gathering system booster stations and processing plants.
Furnace (Condensing) – Furnaces which recirculate the products of combustion and extract available heat to a point that causes condensation to occur. Some of this latent heat of vaporization is recovered as usable energy and results in higher operating efficiencies.
Furnace, Duct – A central furnace designed for installation in a duct of an air distributionsystem to supply warm air for heating and which depends for air circulation on a blower not furnished as part of the furnace.
Gas Central Furnace and Boiler Efficiency Measures – The annual efficiency ratings of furnaces and boilers based on average usage, including on and off cycling as determined by standardized Department of Energy test procedures.
Gas Turbine – A prime mover in which gas, under pressure or formed by combustion, is directed against a series of turbine blades; the energy in the expanding gas is converted into mechanical energy supplying power at the shaft.
Gas, Liquefied Petroleum (LPG) – A gas containing certain specific hydrocarbons which are gaseous under normal atmospheric conditions but can be liquefied under moderate pressure at normal temperatures. Propane and butane are the principal examples.
Gas, Manufactured – A gas obtained by destructive distillation of coal, or by the thermal decomposition of oil, or by the reaction of steam passing through a bedof heated coal or coke, or catalyst beds. Examples are coal gases, coke oven gases, producer gas, blast furnace gas, blue (water) gas, and carburetedwater gas. Btu content varies widely.
Gas, Natural – A naturally occurring mixture
of hydrocarbon and non-hydrocarbon gases found in porous geologic formationsbeneath the earth’s surface, often in association with petroleum. The principa constituent is methane. 1. Dry. Gas whose water content has been reduced by a dehydration process. Gas containing little or no hydrocarbons commercially recoverable as liquid product. Specified small quantities of liquids are permitted by varying statutory definitions in certain states. 2. Liquefied (LNG). 3. Sour. Gas found in its natural state, containing such amounts of compounds of sulfur as to make it impractical touse, without purifying, because of its corrosive effect on piping and equipment. 4. Sweet. Gas found in its natural state, containing such small amounts of compounds of sulfur that it can be used without purifying, with no deleterious effect on piping and equipment. 5. Wet. Wet natural gas is unprocessed natural gas or partially processed natural gas produced from strata containing condensable hydrocarbons. The term is subject to varying legaldefinitions as specified by certain state statutes. (The usual maximum allowable is 7lbs./MMcf water content and .02 gallons/Mcf of Natural Gasoline.)
Gas, Oil – A gas resulting from the thermal decomposition of petroleum oils, composed mainly of volatile hydrocarbons and hydrogen. The true heating value of oil gas may vary between 800 and 1600 Btu per cubic foot depending on operating conditions and feedstock properties.
Gas Pressure Booster – Gas pressure boosters are used for pumping low pressure gas up to the higher levels required by the downstream equipment. It is not a positive displacement pump such as would be used in gas compression for supply distribution, but more closely resembles a blower. The discharge pressure is the total of the incoming gas supply pressure plus the booster added pressure. (Inlet pressure plus boost pressure equals the outlet pressure.) Gas supplied through small piping will lose pressure as the flow increases. However as the gas appliance increases its firing rate, it will require more pressure than available, thus limiting its performance. A gas booster recovers the pressure deficit to allow full capacity operation.
Gas, Synthesis – A mixture of CO and H2 containing small amounts of nitrogen, some carbon dioxide and various trace impurities prepared for petrochemical synthesizing processes.It is also used in the manufacturing of SNG.
Generation, Non-Utility – Generation by producers having generating plants for the purpose of supplying electric power required in the conduct of their industrial and commercial operations. Generation by mining, manufacturing, and commercial establishments and by stationary plants of railroads and railways for active power is included.
Grid – The layout of a gas distribution system in which pipes are laid in both directions in the streets and frequently connected at intersections. Also, a series of equally spaced parallel bars held together by equally spaced crosspieces; a screen.
Head – The differential or pressure, usually expressed in terms of the height of a liquid column that the pressure will support. Also, the differential across a primary measuring device in feet of flowing fluid.
Heat Exchanger, Direct – A heat exchanger in which heat generated in the combustion chamber of the device is transferred directly through walls of the heat exchanger to the heating medium such as air, steam, or water, held in close contact with the combustion-chamber walls. It is a self-contained combustion and heat-transfer device, hence a direct eat-transfer device.
Heat Exchanger, Indirect – A heat exchanger which encloses or contains a heating medium such as air, steam, or water, the heat from which is transferred to another heating medium separately contained in close contact with or directed through the heat exchanger. It is an indirect heat-transfer device.
Heat Joining – Making a pipe joint by heating the mating surfaces of the parts to be joined so that they fuse and become essentially one piece with or without addition of material. NOTE: Also known as Heat fusion and Fusion.
Heat Pump – A year-round air-conditioning system employing refrigeration equipment in a manner which enables usable heat to be supplied to a space during the winter period, and by reversing the operation cycle to extract heat from the same space during the summer period. When operating as a heating system, heat is absorbed from an outside medium (either air, water, or the earth) and thisheat, together with the heat equivalent of the work of compression, is supplied
to space to be heated. When operating on the cooling cycle, heat is absorbed the work of compression, is rejected to the outside medium.
Heat, Specific – The heat required to raise a unit mass of a substance through a degree oftemperature difference. Also, the ratio of the thermal capacity of a substance to that of water at 60 degrees F (15.6 degrees C). Interchangeable with “heat capacity” in common usage.
Heater, Infra-Red Radiant (IR) – A self-contained, vented, or unvented heater used to convert the combustion energy to radiant energy, a substantial portion of which is in the infra-red spectrum, for the purpose of direct heat transfer.
Heater, Make Up Air – A self-contained, vented, or unvented, gas-fired air heater used only to heat air from the outside to replace air which is leaking, being vented, or being discharged from a heated building. May be direct-fired or indirect-fired.
Heater, Room – A self-contained, free-standing, non-recessed (except as noted below), gas-burning, air heating appliance intended for installation in the space being heated and not intended for duct connection. This shall not include heating appliances covered by other American Standard Approval or Listing It may be of either the gravity or mechanical air circulation type, vented, or unvented. (In some areas, this is referred to as a space heater).
Heater, Vented Recessed – A self-contained, vented appliance complete with grilles or equivalent, designed for incorporation in or
permanent attachment to a wall, floor, ceiling, or partition, and furnishing heated air circulated by gravity or by a fan directly into the space to be heated, through openings in the casing. Such appliances shall not be provided with duct extensions beyond the vertical and horizontal limits of the casing proper, except that boots not to exceed 10 inches beyond the horizontal limits of the casing for extension through walls of nominal thickness may be permitted. Where such boots are provided, they shall be supplied by the manufacturer as an integral part of the appliance and tested as such. This definition shall exclude floor furnaces, unit heaters, and central furnaces.
Heating Seasonal Performance Factor (HSPF) – HSPF is an abbreviation for Heating Seasonal Performance Factor. It is the mostcommonly used measure of the heating efficiency of heat pumps. (The cooling efficiency of a heat pump is measured by its SEER.) Technically speaking, the HSPF is a heat pump’s estimated seasonal heating output in divided by the amount of energy that it consumes.
Heating System, High-Temperature Water – A heating system in which water having supply temperature above 350 degrees Fahrenheit is used as a medium to convey heat from a central boiler, through a piping system, to the heating units.
Heating System, Hot Water – A heating system in which water having supply temperatures less than 250 degrees Fahrenheit is used as medium to convey heat from a central boiler, through a piping system, to the heating units.
Heating System, Medium-Temperature Water – A heating system in which water having supply temperatures between 250 and 350 degrees Fahrenheit is used as a medium to convey heat from a central boiler, through a piping system, to the heating units.
Heating Value – The amount of heat produced by the complete combustion of a unit quantity of fuel.The gross of higher heating value is that which is obtained when all of the products of combustion are cooled to the temperature existing before combustion, the water vapor formed during combustion is condensed, and all the necessary corrections have been made. The net or lower heating value is obtained by subtracting the latent heat of vaporization of the water vapor, formed by the combustion of the hydrogen in the fuel, from the gross or higher heating value.
- all products of the combustion are cooled down to the
temperature before the combustion
- the water vapor formed during combustion is condensed
High Btu Oil-Gas Process – A manufactured gas process in which oil is converted into a fuel gas having a higher heating value than that of coal gas or carbureted water gas. Often called Hi-Btu Gas Process.
Horsepower, Boiler – A boiler horsepower is used for boilers in power plants. It is equal to 33,475 Btu/h (9.8095 kW), which is the energy rate needed to evaporate 34.5 lb (15.65 kg) of water at 212 °F (100 °C) in one hour.
Horsepower, Brake – Brake horsepower (abbreviated bhp) is the measure of an engine’s horsepower without the loss in power caused by the gearbox, generator, differential, water pump, and other auxiliary components such as alternator,power steering pump, muffled exhaust system, etc.
Humidifier – A mechanical means of increasing the relative humidity by injecting water or water vapor into the air.
Heating Ventilation and Air Conditioning System (HVAC) – A system that provides either collectively or individually the processes of comfort heating, ventilation and/or cooling within or associated with a building.
Hydrate – A solid ice-like material resulting from the combination of a gas with water under pressure. Of naturalgas constituents — methane, ethane, propane, isobutane, normal butane, andalso hydrogen sulfide and carbon dioxide will form hydrates. The greater the pressure in the equipment, the higher the temperature at which the hydrate will form, usually well above freezing. Hydrates can cause restriction or stoppage of flow, and can be controlled by alcohol injection or by dehydration of the gas. Methane hydrates are found in some permafrost regions and beneath portions
of the ocean floor and may eventually be a source of methane gas.
Hydrocarbon – A chemical compound composed solely of carbon and hydrogen. The compounds having
a small number of carbon and hydrogen atoms in their molecules are usually gaseous; those with a larger number of atoms are liquid, and the compounds with the largest number of atoms are solid.
Hydrogen Sulfide (H2S) – A poisonous, corrosive compound consisting of two atoms of hydrogen and one of sulfur, gaseous in its natural state. It is found in manufactured gas made from coals or oils containing sulphur and must be removed. It is also found to some extent in some natural gas. It is characterized by the odor of rotten eggs.
Ignition, Automatic – A means which provides for automatic lighting of gas at the burner when the gas valve controlling flow is turned on and will effect relighting if the flame on the burner has been extinguished by means other than closing the gas burner valve.
Incremental Cost – The additional costs incurred from the production or delivery of an additional number of units of gas, usually the minimum capacity or production that can be added. The additional cost divided by the additional capacity or output is defined as the incremental cost. Also, in DSM (demand side management), the difference in costs between an efficient technology or measure and the alternative standard technology.
Independent System Operator (ISO) – An organization formed at the direction orrecommendation of the Federa Energy Regulatory Commission (FERC). In the areas where an ISO is established, it coordinates controls and monitors the operation of the electrical power system, usually within a single US State, but sometimes encompassing multiple states.
Similar to an ISO is a Regional Transmission Operator (RTO), the primary difference being that generally an RTO coordinates controls and monitors the operation of the electric power transmission system over a wider area that crosses state borders.
Only electric utilities that are located within the United States fall under FERC authority, but a larger organization called the North American Electric Reliability Corporation (NERC)overlays the entire FERC footprint and also includes a Mexican utility and several Canadian utilities. As such, international reciprocityi commonplace, and rules or recommendations introduced by FERC often are oluntarily accepted by NERC members outside of FERC’s jurisdiction. Therefore, one Canadian Province is a member of a US-based RTO, while two others function as an Electric System Operator (ESO), an organization essentially equal to aUS-based ISO.
Indirect Oven Thermostat System – A control system of two or more integrated automatic devices to maintain a selected oven temperature. That portion of the system responsive to oven temperature causes operation of another portion of the system to turn on or shut off the gas supply to the oven burner.
Indirect-Fired – A heater in which combustion products do not come in contact with the material to be heated; heating of the material is accomplished by radiation or conduction from the heated surfaced.
Indoor Air Quality (IAQ) – Deals with the content of interior air that could affect health and comfort of building occupants. The IAQ may be compromised by microbialcontaminants (mold, bacteria), chemicals (such as carbon monoxide, radon), allergens, or any mass or energy stressor
that can induce health effects. Using ventilation to dilute contaminants, filtration, and source control are the primary methodsfor improving indoor air quality in most buildings. <![if !supportLineBreakNewLine]> <![endif]>
Techniques for analyzing IAQ include collection of air samples, collection of samples on building surfaces and computer modeling of air flow inside buildings.The resulting samples can be analyzed for mold, bacteria, chemicals or otherstressors. These investigations can lead to an understanding of the sources of the contaminants and ultimately to strategies for removing the unwanted elements from the air.
Input Rate – The rate at which gas is supplied to an appliance. It may be expressed in Btu per hour (Btuh), thousands of Btu per hour (MBtuh); in cubic feet perhour (cfh); or thousands of cubic feet per hour (Mcfh); in therms (th) or dekatherms (Dth) per hour.
Input Rating – The gas-burning capacity of an appliance in Btu per hour as specified by the manufacturer. Appliance input ratings are based on sea level operation and need not be changed for operation up to 2,000 feet.
Integrated Resource Planning – A utility planning method whereby alternative resource mixes, including demand-side and supply-side options, are evaluated in order to determine which resource plan minimizes.
Integrating Pressure-and-Temperature Instrument – The integratingpressure-and-temperature instrument registers, on a counter, the total quantityof gas passed through the meter, reduced to standard cubic feet at a definitebase pressure and base temperature. Each increment of volume is multiplied by a temperature-factor corresponding to the line-temperature and base-temperature. It is then multiplied by the pressure-multiplier corresponding to the line
pressure and base pressure. The product is totaled on a counter index. A supplementary index is furnished which reads the total quantity passed at line
Integrating Pressure-Instrument – The integrating pressure-instrument registers the total volume of gas metered in cubic feet at a specified base pressure. This instrument is equipped with a second register which records the total volume at the flowing pressure. Each unit of volume flowing through the meter causes the integrating mechanism to make one cycle and apply the correct pressure multiplier for that unit. The summation of these products is registered on a counter index indicating the displaced volume at base pressure.
Interior Zones – The portions of a building which do not have significant amounts of exterior surfaces. Such zones have heating or cooling needs largely dependent upon internal factors such as lighting.
Internal rate of Return (IRR) – It is an indicator of the efficiency or quality of an investment, as opposed to net present value (NPV), which indicates value or magnitude. The IRR is the annualized effective compounded return rate which can be earned on the invested capital, i.e., the yield on the investment.
A project is a good investment proposition if its IRR is greater than the rate of return that could be earned by alternate investments.
Interruptible Service – Low priority service offered to customers under schedules or contracts which anticipate and permit interruption on short notice, generally in peak-load seasons, by reason of the claim of firm service customers and higher priority users. Gas is available at any time of the year if the supply is sufficient and the supply system is adequate.
Interruptible Transportation Service (ITS) – Low priority service offered to customers under schedules or contracts which anticipate and permit interruption on short notice, generally in peak-load seasons, by reason of the claim of firm service customers and higher priority users.
LEED Rating System – The Leadership in Energy and Environmental Design (LEED) Green Building Rating System™ is a third-party certification program and the nationally accepted benchmark for the design, construction and operation of high performance green buildings. LEED gives building owners and operators the tools they need to have an immediate and measurable impact on their buildings’ performance. LEED promotes a whole-building approach to sustainability by recognizing performance in five key areas of human and environmental health: sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality.
Liquefied Natural Gas (LNG) – Natural gas which has beenliquefied by reducing its temperature to minus 260 degrees Fahrenheit at atmospheric pressure. It remains a liquid at -116 degrees Fahrenheit and 673 psig. In volume, it occupies 1/600 of that of the vapor at standard conditions.
Liquefied Petroleum Gas (LPG) – A gas containing certain specific hydrocarbons which are gaseous under normal atmospheric conditions, but can be liquefied under moderate pressure at normal temperatures. Propane and butane are the principal examples.
Load – The amount of gas delivered or required at any specified point or points on a system; load originates primarily at the gas consuming equipment of the customers. Also, to load a pressure regulator is to set the regulator to maintain a given pressure as the rate of gas flow through the regulator varies.
Manufactured Gas – A gas obtained by destructive distillation of coal, by the thermal decomposition of oil, or by the reaction of steam passing through a bed of heated coal orcoke. Examples are coal gases, coke or oven gases, producer gas, blast furnace gas, blue (water) gas, or carbureted water gas. The Btu content varies widely.
Market Potential – InDSM (demand side management), an estimate of the possible energy savings that would occur because of normal market forces, without the implementation of a DSM (demand side management) program.
Mcf – The quantity of natural gas occupying a volume of one thousand cubic feet at atemperature of sixty degrees Fahrenheit and at a pressure of fourteen and seventy-three hundredths pounds per square inch absolute.
Maximum Daily Quantity (MDQ) – The term MDQ refers to maximum daily quantity of gas which a buyer, seller, or transporter is obligated to receive or deliver at each receipt or delivery point or in the aggregate as specified in an agreement.
Measuring and Regulating Station – Facilities installed at a given location for measuring and regulating the flow of gas in connection with distribution system operations other than the measurement of gas deliveries to customers.
Meter, Rotary (gas meter) – A gas meter is used to measure the volumeof fuel gases such as natural gas and propane. Gas meters are used at residential, commercial, and industrial buildings that consume fuel gas supplied by a gas utility. Gases are more difficult to measure than liquids, as measured volumes are highly affected by temperature and pressure. Gas meters measure a defined volume,regardless of the pressurized quantity or quality of the gas flowing through the meter. Temperature, pressure and heating value compensation must be made to measure actual amount and value of gas moving through a meter.
Meter, Turbine – A velocity measuring device in which the flow is parallel to the rotor axis andthe speed of rotation is proportional to the rate of flow. The volum of gas measured is determined by the revolutions of the rotor and converting them to a continuously totalized volumetric reading.
MMBtu – A thermal unit of energy equal to 1,000,000 Btus, that is, the equivalent of1,000 cubic feet of gas having a heating content of 1,000 Btus per cubic foot, as provided by contract measurement terms.
Modified Fixed-Variable (MFV) Method – A method for classifying fixed costs among demand and commodity charges in which all fixed costs except return on equity capital and related income tax items are classified to the demand charge. This method generally replaced other methods used by the Commission for classifying demand costs when first approved in the mid-1980s. The MFV method of cost classification usually is accompanied with a rate design methodology which employs a two-part (D-1 and D-2) demand and a commodity rate structure.
Monitor – To sense the presence of a flame. The device which does this is called a flame monitor. Also, to analyze and record various desired and undesired components of an atmosphere, or stream of flowing gas or fluid.
Monitoring Regulator – A pressure regulator set in series with a control pressure regulator for the purpose of automatically taking over the control of the pressure downstream in case that pressure tends to exceed a set maximum.
Name PlateRating – The full-load continuous rating of a generator, prime mover, pump, compressor, or other equipment under specified conditions as designated by the manufacturer. It is usually indicated on a name plate attached mechanically to the individualmachine or device.
National Association of Regulatory Utility Commission – A voluntary organization composed of federal and state regulatory commissioners who have jurisdiction over transportation agencies and public utilities.
National Fuel Gas Code – A code that provides general criteria for the installation and operation of gas piping and gas equipment on consumers’ premises. The code is sponsored by both the National Fire Protection Association (NFPA-54) and the American National Standards Institute (ANSI Z223.1).
National Gas Transportation Association (NGTA) – Formerly the National Transportation & Exchange Association. A group that promotes understanding of the national pipeline grid and is working toward standardization in the industry.
Natural Gas Liquids – The hydrocarbon components: propane, butanes, and pentanes (also referred to as condensate), or a combination of them that are subject to recovery from raw gas liquids by processing in field separators, scrubbers, gas processing and reprocessing plants, or cycling plants. The propane and butane components are often referred to as liquefied petroleum gases or LPG.
Normal Recovery Capacity – Amount of water in U.S. gallons raised 100 degrees F per hour or per minute when calculated on a thermal efficiency of 70%, representing the water heated by a gas input of 1,190 Btu per gallon.
Off-Peak – Theperiod during a day, week, month, or year when the load being delivered by a gas system is not at or near the maximum volume delivered by that system for the corresponding period of time.
Oil, Light – Generally, all oils lighter than residual fuel oil No. 5 and No. 6. Oils that have a lowspecific gravity, usually products of controlled distillation of crude oil but also including by-product benzol and toluol.
Open-Flow Test – A test made to determine the volume of gas that will flow from a well in a given time when flowing unrestricted and open to the atmosphere.This is usually calculated from pressure tests of restricted flow.
Oven, Indirect – One in which the flue gases do not flow through the oven compartment.
Oxygen (O2) – A gas which forms about 21%, by volume, of the atmosphere. It is chemically very active and is necessary for combustion. The combination of oxygen with other substances generally produces heat.
Peak Day – The one day (24 hours) of maximum system deliveries of gas during a year. Peak day data is used to, among other things; determine the allocation of certain costs between classes of service. The Commission sometimes required allocation based on an average of three continuous days of maximum deliveries (i.e., three day peak).
Persistence – A measure of the effectiveness, over time, of a DSM (demand side management) measure, usually represented by the percentage of energy savings that remainseach year. A decline in the energy savings of DSM (demand side management) options is usually caused by the following two factors: equipment degradation and consumer behavior.
Petroleum – An oil, flammable bituminous liquid that may vary from almost colorless to black, occurs in many places in the upper strata of the earth; is a complex mixture of hydrocarbons with small amounts of other substances, and is prepared for use as gasoline, naphtha, or other products by various refining processes.
Pilot Program – ADSM (demand side management) program that is generally limited in scope or targeted to a select group of customers and is designed to test or build capability to deliver a full scale program.
Pilot, Expanding – A pilot that burns throughout the entire time the burner assembly is in service, whether the main burner is firing or not. Upon a call for heat, the pilot is automatically expanded so as to reliably ignite the main burner. This pilot may be turned down automatically at the end of main burner flame-establishing period.
Pipeline – All parts of those physical facilities through which gas is moved in transportation, including pipe, valves, and other appurtenances attached to pipe, compressor units, metering stations, regulator stations, delivery stations, holders, and fabricated assemblies.
Potential – A measure of the capacity of a well to produce oil or gas. When a well is completed, its productive capacity is determined by an official test. The capacity as shown by this test is known as the well’s potential. The allowablerate of production assigned to the well is based in whole or in part on its potential.
Power Combustion Furnaces – Furnaces that have a combustion blower, which may be located either upstream or downstream from the heat exchangers. If the blower is located upstream, blowing the combustion air into the heat exchangers, the system is called a forced-draft system. If the blower is downstream, the arrangement is called an induced-draft system. Power combustion systems have been commonly used with outdoor furnaces in the past;however, more indoor furnaces are being designed using this concept.
Pressure Regulating Station – Equipment installed for the purpose of automatically reducing and regulating the pressure in the downstreampipeline or main to which it is connected. Included are piping auxiliary devices such as valves, control instruments, control lines, the enclosures, and ventilating equipment.
Pressure, Absolute (PSIA) – Pressure in excess of aperfect vacuum. Absolute pressure is obtained by algebraically adding gauge pressure to atmosphere pressure. Pressures reported in “Atmospheres” are understood to be absolute. Absolute pressure must be used in equations of state and in all gas-law calculations. Gauge pressures below atmosphericpressure are called “vacuum.”
Pressure, Atmospheric – The pressure due to the weight of the atmosphere (air and water vapor) on the earth’s surface. Theaverage atmospheric pressure at sea level (for scientific purposes) has been defined at 14.696 pounds per square inch absolute.
Preventive Maintenance – Examination of plant and equipment on a schedule basis and the replacement or repair ofparts that are worn by prescribed amounts or that are in such condition that further use will involve the risk of their failure while in service. It is designed to prevent operating breakdown.
Propane (C3H8) – A gas, the molecule of which is composed of three carbon and eight hydrogen atoms. Propane is present in most natural gas and is the first product refined from crude petroleum. It has many industrial uses and may be used for heatingand lighting. Contains approximately 2,500 Btu per cubic foot.
Psychometric – Pertaining to the state of the atmosphere with reference to moisture.
Public Utility – A business organization performing a service relating to or affecting all of the people within a specified area, usually under provisions of a franchise, charter or “certificate”, and subject to special governmental regulations. See SERVICE AREA.
Purge Cycle – Asapplied to electric pilot igniters, the period from the time of automatic closure of the main gas supply by the safety shutoff device to the time the electrical circuit is re-energized.
Purification – Theprocess by which unwanted impurities, such as hydrogen sulfide, are removed from a gas mixture. Purification of gas is accomplished by two principal methods. The dry method in which the gas is passed through some purifying material such as iron oxide mixed with wood shavings, and the wet method in which the gas is brought in contact with some liquid containing an active purifying agent such as ethanolamine or arsenic trioxide.
Qualifying Facility (QF) – Qualifying facilities are a distinct class of energy producer which consists of either small-scale producers of commercial energy who normally self-generate energy for their own needs but may have occasional or frequent surplus energy, or incidental producers who happen to generate saleable electric energy as a byproduct of other activities. When a facility of this type meets the Federal Energy Regulatory Commission’s requirements for ownership, size and efficiency, utility companies are obliged to purchase energy from these facilities based ona pricing structure referred to as avoided cost rates. These rates tend to behighly favorable to the producer, and are intended to encourage more productio of this type of energy as a means of reducing emissions and dependence on other sources of energy.
Qualifying facilities were first classified in 1978 with the establishment of the Public Utility Regulatory Policies Act, a piece of legislation which was intended to encourage more efficient and environmentallyfriendly energy production in the United States.
Radiator – A heating unit which transfers heat by radiation to objects within visible range and by conduction to the surrounding air which, in turn, is circulated by natural convection; a so-called radiator is also a convector, but the term radiator has been established by long usage.
Range, Gas – Cooking stove. GAMA lists the following types: (1) Free-standing; (2) Set-in; (3) High Oven; (4) Built-in, Commercial; (5) Luncheonette and Restaurant; (6) Heavy Duty (Quality, Battery Type).
Rate of Return – The return allowed to be earned (generally based on a cost of capital determination) or earned by a utility enterprise, generally calculated by dividing the net operating income (as defined) by the rate base.
Rate Schedule, Cogeneration – A special rate to encouragecommercial and industrial customers to use gas-fired cogeneration (generates their own electricity and use the waste heat from this process for thermal requirements).
Rates, Meter – The term “meter rate” is applicable to any method of charge for gasservice based solely upon quantity, such as Mcf or therms used. The term “block” indicates that a certain specified price per unit is charged for all units of gas taken within specified increments of use. Reduced prices per unit are charged for all or any part of succeeding blocks of such units, each such reduced price per unit applying only to a particular block or portion thereof. The term “inverted” indicates that an increasing unit charge will be applied to succeeding blocks of increasing energy use. The term “step” indicates that a certain specified price per unit is charged for all gas taken during a billing period, the rate, or price depending on the particular step within which the total consumption falls. The term “straight-line” indicates that the price charged per unit is constant, i.e., does not vary on account of an increase or decrease in the number of units.
Ratio of Specific Heats – For gases: The ratio of thespecific heat at constant pressure to the specific heat at constant volume. This ratio is important in thermodynamic equations, and is given the symbol kwhere k=cp/cv. The ratio k lies between 1.2 and 1.4 for most gases.
Rebate Program – A DSM (demand side management) program in which the utility offers a financial incentive for the installation of energy-efficient equipment. Non-DSM (demand side management) rebate programs also exist, in which the utility offers an incentive for purposes of gaining market share of a specific end-use.
Refrigerant – A substance which will absorb heat while vaporizing and whose boiling point and other properties make it useful as a medium for refrigeration. (Chilled water, which by common acceptance is called a refrigerant, does not vaporize).
Refrigerating System, Vapor-Compression – A refrigerating system in which the cooling effect results from expansion of a refrigerant aftermechanical compression by either centrifugal or reciprocating compressors.
Regulator, Domestic Appliance Pressure – A device either adjustable or non-adjustable for controlling and maintaining a uniform outlet gas pressure. Spring Type, Adjustable – A regulator in which the regulating force acting upon the diaphragm is derived principally from a spring, the loading of which is adjustable. Spring Type, Nonadjustable – A regulator in which the regulating force acting upon the diaphragm is derived principally from a spring, the loading of which is not adjustable. Either of the above types may be further classified as follows: Main Burner Load Application – A regulator capable of controlling the flow of gas to main burners only. In such applications, the pilot is taken off upstream from the regulator. Main Burner and Pilot Load Application – A regulator capable of controlling the flow of gas to main and pilot burners. In such applications the pilot is taken off downstream from the regulator valve.
Regulator, Monitoring – A pressure regulator set in series with a control pressure regulator for the purpose of automatically taking over, in an emergency, the control of the pressure downstream of the station in case that pressure tends to exceed a set maximum.
Regulator, Pressure – A device that maintains the pressure in a fluid flow line, less than its inlet pressure within a constant band of pressures, regardless of the rate of flow in the line or the change in upstream pressure.
Relief Opening – The opening provided in a draft hood to permit the ready escape to the atmosphere of the flue products from the draft hood in the event of no draft, back draft, or stoppage beyond the draft hood, and to permit inspiration of air into the draft hood in the event of a strong chimney updraft.
Return on Investment (ROI) – A performance measure used to evaluate the efficiency of an investment or to compare the efficiency of a number of different investments. To calculate ROI, the benefit (return) of an investment is divided by the cost of the investment; the result is expressed as a percentage or a ratio.
Safety Engineering – The planning, development, improvement, coordination and evaluation of the safety component of integrated systems of people,materials, equipment and environments to achieve optimum safety effectiveness in terms of protection of people and property.
Safety Shutoff Device – A device that will shut off the gas supply to the controlled burner(s) in the event the source of ignition fails. This device may interrupt the flow of gas to the main burner(s) only or to the pilot(s) and main burner(s) under its supervision.
Schematic – Anoutline, systematic arrangement, diagram, scheme, or plan. An orderly combination of events, persons, or things according to a definite plan. A diagram showing the relative position and/or function of different components or elements of an object or system.
SeasonalEnergy Efficiency Ratio (SEER) – The energy efficiency measurement for central air conditioners is measured in a unit called SEER – seasonal energy efficiency ratio. The SEER is the cooling output divided by the power consumption, with climate and other variables factored in. The higher the SEER, the better – a rating of 10 is considered the minimum for new systems. Older systems might have a SEER of 7 or 8 – or even less. The SEER will be listed prominently on the yellow-and-black EnergyGuide.
Solar Cell – A solar cell, also called a photovoltaic cell, is used to convert solar energy into electrical energy. Solar cells are the basic elements of a solar module (also known as a solar panel). Silicon is by far the commonest of a variety of semiconductors from which solar cells are made. A typical modern solar cell is squared-shaped measuring 10 cm × 10 cm. It is covered by a clear anti-reflection coating (ARC) that reduces the amount of light lost to reflection at the cell surface.
Specific Heat – The heat required to raise a unit mass of a substance through a degree of temperature difference. Also, the ratio of the thermal capacity of a substance to that of water. The specific heat of fluids varies with temperature and pressure.
Strategic Load Growth – A targeted increase in end-use consumption during certain time periods or among certain customer types. The result is a general increase in energy sales beyond the valley filling strategy. Strategic load growth may involve increased market share of loads that are, or can be, served by competing fuels, as well as area development.
Substitute Natural Gas (SNG) – A gas manufactured from carbonaceous material whose characteristics are substantially interchangeable with natural gas. The resultant gas is composed primarily of methane. At this writing, SNG feedstocks are the light hydrocarbons, propane, butane, and the naphthas. Development is underway of processes for production from heavier feedstocks, coal, peat, and solid wastes.
Synthetic Natural Gas – A descriptive term used interchangeably with SNG and Substitute Natural Gas. It is a gas manufactured from naphtha, coal, etc., and is substituted for, or mixed with, natural gas by a pipeline or gasdistribution utility.
Temperature, Ambient – Thetemperature of the air, atmosphere or other fluid that completely surrounds the apparatus, equipment or the work piece under consideration. For devices which do not generate heat, this temperature is the same as the temperature of themedium at the point of device location when the device is not present. For devices which do generate heat, this temperature is the temperature of themedium surrounding the device when the device is present and generating heat.Allowable ambient-temperature limits are based on the assumption that the device in question is not exposed to significant radiant-energy sources such as sunlight or heated surfaces.
Temperature, Effective – An arbitrary index which combines into a single value the effect of temperature, humidity, and air movement on the sensation ofwarmth or cold felt by the human body. The numerical value is that of the temperature of still, saturated air which would induce an identical sensation.
Temperature, Wet Bulb – The temperature an air parcel would have if cooled adiabatically to saturation at constant pressure by evaporation of water from it, all latent heat being supplied by the parcel.
Temperature-Compensated Meters – These meters measure volume temperature to volume at base temperature. These temperature compensators use a temperature-sensitive device to continuously vary the diaphragm-stroke to provide a temperature-compensated volume output. Meters equipped with temperature-compensators are often identified by red badges on the index face.
Thermostat – An automatic device actuated by temperature changes designed to control the gas supply to the burner(s) in order to maintain temperature between predetermined limits, and in which thethermal actuating element is an integral part of the device: 1. Electric Switch Type: A device which senses changes in temperature and control electrically, by means of separate components, the flow of gas to the burner(s) to maintain selected temperature. 2. Graduating Thermostat: A thermostat in which the motion of the thermostat valve is in direct proportion to the effective motion of the thermal element induced by temperature change. 3. Quick-Acting Graduating Thermostat: A thermostat which changes from the completely closed position, or vice versa, but not with a snap. 4. Snap-Acting Thermostat: A thermostat in which the thermostatic valve travels instantly from the closed to the open position, or vice versa.
Total Energy – A concept under which the electricity required by a given facility is producedon-site by natural gas and possible alternate standby fueled engines or turbines with the recovery of the equipment’s heat of rejection for space conditioning and/or process uses.
Trade Ally – In DSM (demand side management), an organization (architect, building contractor, etc.) that influences energy decisions of customers who are potential DSM (demandside management) program participants.
Transmission Company, Gas – A company which obtains at least 90% of its gas operating revenues from sales for resale and/or transportation of gas for others and/or main line sales to industrial customers and classifies at least 90% of its mains (other than service pipe) as field and gathering, storage, and/or transmission.
Tube, Injection – A tube with a venturi throat which leads from the primary air port and gas orifice or a gas burner to mixing chamber and burner ports. As the gas passes from the gas orifice through the tube, it draws air through the primary airport into the mixing chamber, after which the mixture is burned at the burner ports.
Turbine, Steam or Gas – An enclosed rotary type of prime mover in which heat energy in steam or gas is converted into mechanical
energy by the force of a high velocity flow of steam or gas directed againstsuccessive rows of radial blades fastened to a central shaft. Compare ENGINE, RECIPROCATING.
Turbine Inlet Cooling (TIC) – TIC is cooling of the ambient air before it enters the compressor that supplies high-pressure air to the combustion chamber from which hot air at high pressure enters thecombustion turbine. TIC is also called by many other names, including combustion turbine inlet air cooling (CTIAC), turbine inlet air cooling (TIAC), combustion turbine air cooling (CTAC), and gas turbine inlet air cooling (GTIAC).
U-Factor – The quantity of heat transmitted per hour through one square foot of a building section (wall, roof, window, etc.) for each degree Fahrenheit of temperaturedifference between the air on the warm side and the air on the cold side of the
U.S. Green Building Council (USGBC) – A non-profit organization committed to expanding sustainable building practices. USGBC is composed of more than 15,000 organizations from across the buildingindustry that are working to advance structures that are environmentally responsible, profitable, and healthy places to live and work. Members includes building owners and end-users, real estate developers, facility managers, architects, designers, engineers, general contractors, subcontractors, product and building system manufacturers, government agencies, and nonprofits.
Valve, Automatic Input Flow Control – A device for controlling the gas supply to the main burner without manual attention.
Valve, Back Pressure – A valve built to maintain agiven pressure in a piping system by remaining in a closed position until the given pressure is reached, at which time it opens to permit flow until the pressure falls below the specified pressure.
Valve, Manual Main Shut-Off – A manually operated valve or stop in the gas line for the purpose of completely turning on or shutting off the gas supply to the appliance except to pilot or pilots which are provided with independent shut-off valves.
Valve, Relief – An automatic valve designed to discharge when a preset pressure and/or temperaturecondition is reached. 1. Pressure Relief Valve. An automatic valve which opens and closes a relief vent, depending on whether the pressure is above or below a predetermined value. 2. Temperature ReliefValve. A. Fusible Type. A valve which opens and keeps open a relief vent by the melting or softening of a fusible element at a predetermined temperature. B.Manual Reset Type. A valve which automatically opens a relief vent at a predetermined temperature and which must be manually returned to the closed position. C. Reseating or Self-Closing Type. An automatic valve which opens and closes a relief vent when the temperature reaches a predetermined value. D. Vacuum Relief Valve. An automatic valve which opens or closes a vent for relieving a vacuum, depending on whether the vacuum is above or below a predetermined value. Frequently used in a hot water supply system.
Valve, Safety Shut-Off (Cut-Off) – A valve which automatically shuts off the supply of fuel through the functioning of a flame safeguard control or limiting device. This device may interrupt the flow of fuel to the main burner(s) only or to the pilot(s) and main burner(s).
Valve, Shut-Off – Stops or valves readily accessible and operable by the consumer, located in the piping system (to shut off individual equipment) or between the meter and gas main to shut off the entire piping system.
Vapor – The gaseous state of a substance as distinguished from permanent gases. A gaseous fluid may be classified as either a vapor or a gas. If it is near the region of condensation, it is called a vapor. If it is well above the region of condensation, it is called a gas. Vapors in general do not follow the ideal gas law, and engineers prefer to use tables and charts based on experimental data when working with vapors. Gases, however, may obey the ideal gas laws over a wide range of temperature and pressure.
Variable Cost – Operating costs which, in the aggregate, vary either directly or indirectly in relation to any change in the volume of gas sold and/or transported; i.e., compressorstation fuel and expenses.
Vent – An opening in a tank or other piece of equipment, sealed to prevent escape of material within the equipment at normal pressures but so arranged that it automatically opens to relieve excessive pressure in the equipment. Can be arranged for manual opening to depressure equipment as desired. Also, the relief opening in a pressure regulator, normally open to the atmosphere.
Vent Damper – A device installed in the vent pipe that connects the furnace to the chimney.When the burner goes off, the damper closes automatically, restricting the amount of heated air that can be lost through the chimney.
Water Heater Efficiency Measures – Energy Factor (EF) – A measure of the overall efficiency of a water heater based on its recovery efficiency, standby loss and energy input as set out in the standardized Department of Energy test procedures.
Water Heater , Tankless – Provide hot water only as it is needed. A tankless water heater is used only when there is a demand for hot water. They heat water directly without the use of a storage tank. Therefore, they avoid the standby heat losses associated with storage water heaters. In an electric Tankless Water Heater an electric element heats the water. In a gas-fired Tankless Water Heater a gas burner heats the water. As a result, Tankless Water Heaters deliver a constant supply of hot water.
Water Piping System, Closed – A heating system utilizing anair tank which provides a means of pressurizing the system for operation over a wide range of conditions and of circulating water which is used as a heat medium.
Water Source Heat Pump (geothermal heat pump) – Water source heat pumps, also known as geothermal heat pumps, use the constant temperature of the earth as the exchange medium instead of the outside air temperature. This allows the system to reach fairly high efficiencies (300%-600%) on the coldest of winter nights, compared to 175%-250% for air-source heat pumps on cool days.
Zone Heat – A central heating and/or cooling system which is arranged so that different temperatures can be maintained in two or more areas of the building being heated or cooled or simultaneously heated or cooled.