Appendix A: Glossary

aMW

Average megawatt is calculated by totaling the annual power consumed in a year (in this case megawatts or MW) and dividing that total annual consumption by the number of hours in given year (typically 8,760 during non-leap years). In Electricity Supply Planning, the average megawatt can provide useful context for understanding the average energy required to meet demand on an annualized basis.

Advanced Metering Infrastructure (AMI)

Advanced metering infrastructure (AMI) is an integrated system of meters, communications networks, and data management systems that enables two-way communications between utilities and customer meters.

Balancing

Balancing or matching load with resources to meet demand. Commonly referred to as load/resource balance.

Annualized Fuel Utilization Efficiency (AFUE)

Annualized Fuel Utilization Efficiency (AFUE) Furnaces are rated by the Annual Fuel Utilization Efficiency (AFUE) ratio, which is the percent of heat produced for every dollar of fuel consumed. Any furnace with an efficiency of 90% or higher is considered high efficiency.

Benefit/Cost Ratio (BCR)

A ratio used to summarize a benefit-cost analysis to determine if a proposed project’s benefits outweigh the costs. If the BCR is greater than one, the net present value of acting is expected to be positive. If the BCR is less than one, the costs outweigh the benefits.

BTU and BTUH

British Thermal Unit (BTU) is a measure of heat energy. BTUH is British Thermal Unit per hour. One BTU is the amount of energy needed to raise 1 pound of water by one degree Fahrenheit.

Capacity Utilization

Capacity utilization measures the maximum rate of potential output used over a set period.

Carbon

Short for carbon dioxide, a greenhouse gas produced by burning fossil-based fuels and other sources.

Carbon Intensity

The amount of carbon emitted per unit of energy consumed.

Capacity

The maximum output or electrical rating, commonly expressed in megawatts (MW).

Capacity Factor

The ratio of the net electricity generated, for the time considered, to the energy that could have been generated at continuous full-power operation during the same period.

Climate Change

The rise in average surface temperatures on Earth due primarily to the human use of fossil-based fuels, which releases carbon dioxide and other greenhouse gases into the air.

CEJST

The Climate and Economic Justice Screening Tool (CEJST) is a geospatial mapping tool to identify disadvantaged communities and is used to support the Federal Government’s Justice40 Initiative.

Coefficient of Performance (COP)

An efficiency ratio that measures useful heating or cooling provided relative to the work required. In electric heat pumps, this is the relationship between the energy that is delivered from the heat pump as cooling or heat (BTUh is converted to equivalent power kW), and the power (kW) that is supplied to the compressor.

Coincident Demand

The sum of two or more demands that occur in the same time interval.

Cold Climate Heat Technology

The most efficient type of air source heat pump designed for cold climates using variable speed drive compressor technology.

Commodity

An economic good that can be bought and sold and interchangeable with other goods of the same type.

Controlled Charging

Controlled or managed EV charging enables the utility and customer to align charging behavior that will potentially mitigate higher costs and carbon impacts during peak demand hours.

Cost-parity

Same price for product that is equivalent in value.

Critical Peak Pricing

Critical peak pricing is a price-responsive mechanism designed to incentivize customers to reduce or shift electricity usage during a critical event.

Demand

The rate at which energy is being used by the customer.

Demand Response (DR)

Demand response is a measure to reduce or shift electricity usage during peak periods or as a response to supply constraints.

Demand Side Management (DSM)

An action to effectively reduce or modify the demand for energy. DSM is often used to reduce load during peak demand and/or in times of supply constraint.

Direct Air Capture

A technology to capture CO2 from the atmosphere.

Direct Load Control (DLC)

The consumer load that can be interrupted at the time of peak load by direct control of the utility.

Discounted Cash Flow

A method to estimate the present value of an investment based on the expected future cash flows.

Discount Rate

The interest rate used to determine the present value of future cash flows.

Dispatchable

The operating control of an integrated electric system involving operations such as the assignment of load to specific generating stations and other sources of supply to affect the most economical supply as the total or the significant area loads rise or fall.

Distributed Generation (DG)

Distributed generation (sometimes call Distributed Energy Resources – DER) refers to systems that generate electricity at or near the load it is intended to serve (thereby reducing transmission needs/costs) and connected to the distribution system.

Distribution Assets

The portion of the electric system’s poles, transformers, and other equipment dedicated to delivering electricity at the required voltage for the end-user.

Distribution Capacity

The installed capacity and capable load of individual circuits within the distribution asset system.

Diurnal

Diurnal variation refers to daily fluctuations.

Disadvantaged Communities (DAC)

By the Justice 40 Federal definition, disadvantaged communities are those that are marginalized, underserved, and overburdened by pollution.

Duct System

A system of tubes and pipes used for heating, ventilation, and air conditioning.

Electric Panel

The electric service panel or circuit breaker box connects the main power line and distributes electrical currents to circuits within a home or building.

Electric Vehicle (EV)

A vehicle that derives all or part of its power from electricity supplied by the electric grid. Primary EV options include battery, plug-in hybrid, or fuel cell.

(1) Battery Electric Vehicles (BEV) typically do not have an internal combustible engine (ICE) or fuel tank and rely solely on its battery charged by electricity to operate the vehicle. Typical driving ranges are less ICE vehicle options but newer models with advanced battery technology support higher ranges.

(2) Plug-in Hybrid Electric Vehicles (PHEV) are powered by an on-board battery and gasoline with the ability to operate solely on its battery, ICE, or a combination of both. When the battery is fully charged and gasoline tank full, the PHEV driving range is comparable to a conventional ICE vehicle.

(3) Fuel Cell Electric Vehicles (FCEV) run on compressed liquid hydrogen. Combining hydrogen with oxygen generates the electrical energy that either flows to the motor or to the battery to store until it’s needed. FCEVs have a driving range comparable to a conventional ICE vehicle.

Electric Vehicle (EV) Charging Stations

EV charging stations typically fall under three primary categories: Level 1, Level 2, and Level 3 also referred to as DC Fast Chargers. 

Level 1: Provides charging through a 120 V AC plug and does not require installation of additional charging equipment. Can deliver 2 to 5 miles of range per hour of charging. Most often used in homes, but sometimes used at workplaces. 

Level 2: Provides charging through a 240 V (for residential) or 208 V (for commercial) plug and requires installation of additional charging equipment. Can deliver 10 to 20 miles of range per hour of charging. Used in homes, workplaces, and for public charging. 

DC Fast Charge: Provides charging through 480 V AC input and requires highly specialized, high-powered equipment as well as special equipment in the vehicle itself. (Plug-in hybrid electric vehicles typically do not have fast charging capabilities.) Can deliver 60 to 80 miles of range in 20 minutes of charging. Used most often in public charging stations, especially along heavy traffic corridors.

End Use

The use of energy for a specific purpose where electricity is converted into useful work. Examples include transportation, heating, or cooling.

Energy Efficiency (EE)

Refers to programs that are aimed at reducing the amount energy used in homes and other buildings. Examples include high-efficiency appliances, lighting, and heating systems.

Energy Efficiency Ratio (EER)

The Energy Efficiency Ratio (EER) of an HVAC cooling device is the ratio of output cooling energy (in BTU) to input electrical energy (in watts) at a given operating point.

Energy Factor (EF)

The energy factor (EF) indicates a water heater's overall energy efficiency based on the amount of hot water produced per unit of fuel consumed over a typical day.

Fossil Fuel

An energy source formed in the Earth's crust from decayed organic material. The common fossil fuels are petroleum, coal, and natural gas.

Generation

The process of producing electricity from water, wind, solar, fossil-based fuels, and other sources.

Generation Capacity

The maximum output, commonly expressed in megawatts (MW), that generating equipment can supply to system load.

Green

Green or clean electricity produced with little-to-no environmental impact or contributes to global warming caused by greenhouse gas emissions.

Greenhouse Gas (GHG) Emissions

GHG emissions are gases, such as carbon dioxide, that trap heat in the atmosphere. The largest source of GHG emissions from human activities in the U.S. is from burning fossil-based fuels for electricity, heat, and transportation.

Grid

The electricity grid, or grid, refers to the system that moves electricity from its source through transformers, transmission lines, and distribution lines to deliver the product to its end-user, the consumer.

Heat Pump

Heating and/or cooling equipment that, during the heating season, draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling.

Heating seasonal performance factor (HSPF)

Heating seasonal performance factor (HSPF) is a term used in the heating and cooling industry. HSPF is specifically used to measure the efficiency of air source heat pumps. HSPF is defined as the ratio of heat output (measured in BTUs) over the heating season to electricity used (measured in watt-hours).

HVAC

HVAC is an acronym for heating, ventilation, and air conditioning.

Incremental Cost

See Marginal Cost.

Inflation

The growth rate of a price index. Inflation occurs when the purchasing power of your dollars decreases due to rising prices.

Integrated Resource Plan (IRP)

An IRP is a plan that outlines how a utility will meet its future electricity needs over a long-term planning horizon.

Interval Metering

Interval metering data is a series of measurements of energy consumption, taken at pre-defined intervals, typically sub-hourly. In end-use studies, energy consumption is measured in 15-minute or 1-minute granularity.

Intra-day Net Load Ramping

Net load ramping occurs within the day when renewable generation decreases at the same time load rises.

Justice 40 Initiative

The goal set by the Federal Government under the Biden Administration that 40% of the overall benefits of certain Federal investments (IIJA, IRA, etc.) flow to disadvantaged communities that are marginalized, underserved, and overburdened by pollution. These communities are mapped in the US using the Climate and Economic Justice Screening Tool (CEJST).

Light-duty Vehicles

Light duty refers to gross vehicle weight rating and includes passenger cars, SUVs, trucks, and vans that weigh up to 10,000 pounds.

Line-loss

The amount of electricity lost during the transmission and distribution phases as it travels across the grid.

Load

The amount of electricity on the grid at any given time, as it makes its journey from the power source to all the homes, businesses.

Load Shape

A method of describing peak load demand and the relationship of power supplied to the time of occurrence. Interval metering of end-uses is one method used to develop a load shape.

Marginal Cost

The change in cost associated with a unit change in quantity supplied or produced.

Marginalized Communities

Communities that experience discrimination and exclusion from social, economic, and/or cultural life.

Market-based pricing

Prices of electric power or other forms of energy determined in an open market system of supply and demand under which prices are set solely by agreement as to what buyers will pay and sellers will accept. Such prices could recover less or more than full costs, depending upon what the buyers and sellers see as their relevant opportunities and risks.

Market Liquidity

Market liquidity refers to the extent a market, such as the wholesale electricity market or real estate market, allows assets to be bought and sold with price transparency.

Megawatt (MW)

The standard term of measurement for bulk electricity. One megawatt is 1 million watts. One million watts delivered continuously 24 hours a day for a year (8,760 hours) is called an average megawatt.

Mini-Split Ductless System

A ductless heating and cooling system for use in smaller spaces or individual rooms. Mini-split systems have two main components: an outdoor compressor/condenser and an indoor air-handling unit(s).

MPGe

Miles per gallon of gasoline equivalent. Think of this as being like MPG, but instead of presenting miles per gallon of the vehicle’s fuel type, it represents the number of miles the vehicle can go using a quantity of fuel with the same energy content as a gallon of gasoline. This allows a reasonable comparison between vehicles using different fuels.

MSRP

MSRP is the acronym for manufacturer’s suggested retail price.

MTCO2e

Metric tons of carbon dioxide equivalent are a unit of measurement. The unit "CO2e" represents an amount of a GHG whose atmospheric impact has been standardized to that of one unit mass of carbon dioxide (CO2), based on the global warming potential (GWP) based on the global warming potential (GWP) of the gas.

NESC

National Electric Safety Code.

Nominal Dollar

Nominal or current dollars have not been adjusted for inflation.

Noncoincident Demand

Sum of two or more demands on individual systems that do not occur in the same demand interval.

1-in-2 or 1-in-10

A statistical measure used for risk analysis. The probability or chance of something occurring one year such as a one-hour peak in year 2, 1-in-2 year, is 1 / 2 or 50%. A 1-in-10 year has 1/10 or 10% chance of occurring in any one year.

Peak Demand

The largest instance of power usage in a given time frame.

Peak Diversity Factor

Peak Diversity Factor is the ratio of coincident peak demand to the non-coincident peak demand over a given period. This ratio illustrates the relationship between the peak electricity use of a population relative to the sum of all individual peak electricity use within the population. A high peak diversity factor (100%) indicates that the individual units within the population peak simultaneously, whereas a low peak diversity factor illustrates that individual units within the population peak at different times.

Peak Time Rebate

A pricing mechanism designed to incentivize reducing energy during peak time events by offering a rebate.

Peaker Plant

Peaker plant, also known as a peaking power plant or simply peaker, is a power plant that generally runs during times when demand for electricity is high or at its peak time. Peaker plants are typically gas turbines that burn natural gas.

Photovoltaic (PV)

PV is the process of converting sunlight into electrical energy using semiconducting materials.

Power

The rate of producing, transferring, or using energy, most associated with electricity. Power is measured in watts and often expressed in kilowatts (kW) or megawatts (MW).

PUC

Public Utility Commission.

Quad

Quadrillion Btu 10¹⁵ Btu. The quantity 1,000,000,000,000,000(10 to the 15th power).

Qualitative

Qualitative data is descriptive, conceptual, and is non-numerical.

Quantitative

Quantitative data is anything that can be counted, measured, or quantified using a numerical value.

Real-time

Actual time of occurrence.

Real-time Pricing

Real-time Pricing is designed to charge each kWh delivered based on fluctuating wholesale prices or production costs.

Renewable Natural Gas (RNG)

RNG is derived from the decomposition of organic waste and has lower carbon emissions than conventional natural gas.

Residential Building Stock Assessment (RBSA)

An assessment developed to capture the residential building sector that considers building practices, fuel choices, and diversity of climate across the region.

Resource Adequacy

Ensuring there are sufficient generating resources when and where they are needed to serve the demands of electrical load in “real time” (i.e., instantaneously). An adequate physical generating capacity dedicated to serving all load requirements to meet peak demand and planning and operating reserves, at or deliverable to locations and at all times.

Resource Portfolio

All the sources of electricity provided by the utility.

Scenario

A projection or forecast that provides a framework to explore plausible outcomes. Scenario analysis is the process of analyzing plausible outcomes and typically includes base-case, expected-case, and worst-case scenario analysis.

Sector

Group of major energy consumers developed to analyze energy use. Commonly referred to as residential, commercial, industrial, and transportation sectors.

Segment

Customer segmentation or segment means separating the diverse population of end-use customers in groups based on similarities in customer needs and preferences.

Sensitivity

Sensitivity analysis is a method to determine how changes in methods, models, values of variable or assumptions may lead to different interpretations or conclusions by assessing the impact, effect or influence of key assumptions or variable.

Social Cost of Carbon

The estimated economic damage in dollars from emitting one ton of carbon dioxide.

Therms

A measurement of heat energy in natural gas. One unit of heat is equal to 100,000 British thermal units (BTU).

Time of Use (TOU) Rate

Time of use rates are rate structures which incent a customer to change their electric usage patterns, because they typically charge higher prices for consumption during peak periods.

Total Lifecycle

Lifecycle of a targeted measure refers to the expected life from the time the product is introduced in the market until it’s removed.

Transformer

An electrical device for changing the voltage of alternating current.

Transmission

An interconnected group of lines and associated equipment for the movement or transfer of bulk energy products from where they are generated to distribution lines that carry the electricity to consumers.

Transmission Capacity

The maximum line and associated equipment available to move or transfer bulk energy across a transmission system.

Uncontrolled Charging

Uncontrolled charging allows for charging at any time of time without restraints including differences in price to charge. Also known as unmanaged charging.

Uniform Energy Factor (UEF)

A water heater's UEF rating is a measure of its energy efficiency, with higher numbers denoting more efficient units. The UEF calculation is based off how much energy the water heater uses and how much energy is used to power the water heater itself.

Upstream Emissions

Upstream typically refers to accounting for the all the emissions associated with extracting and processing resources used to create energy.

Variable Generation

Variable generation is produced using renewable resources (e.g., solar, wind, or run-of-river hydro) that is intermittently available.

Voltage

The difference in electrical potential between any two conductors or between a conductor and ground. It is a measure of the electric energy per electron that electrons can acquire and/or give up as they move between the two conductors.

Wholesale Market

The market for buying and selling of electricity before it is sold to the end-user.