Glossary of Energy Efficiency Terms and Definitions
The technical jargon associated with energy efficiency can be overwhelming. To help you better understand this terminology, we have created a guide for consumers with some basic definitions for quick reference:
- Air Sealing
- The process of sealing the leaky nooks and crannies in your house often with caulk, spray foam or weather stripping.
Practical info: this is often the most cost effective way to increase a home’s energy efficiency and improve how well your insulation will work.
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- Btu (British thermal unit)
- A fuel's energy content typically is shown in Btu. The quantity of heat needed to raise the temperature of 1 pound of water by 1 degree Fahrenheit at or near 39.2 degrees.
Practical info: 3413 BTU = 1 kWh of electricity. Burning one wooden matchstick provides about one Btu.
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- Building Performance Institute (BPI)
- Organization whose goal is to enhance the health, safety, comfort, durability, and energy efficiency of residential buildings by providing skills verification and promoting best practices. www.bpi.org
Practical info: BPI-accredited contractors must pass rigorous written exams as well as field exams where they demonstrate their competency.
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- CCF
- A measurement of space or volume -- the amount of gas contained in a space equal to one hundred cubic feet.
Practical info: A CCF is approximately equivalent to 1 therm. Convert CCFs to therms, to perform price comparisons.
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- CFL
- A compact fluorescent light bulb. It uses 75 percent less energy than a traditional incandescent bulb.
Practical info: A single CFL saves approximately $30 over its lifetime and will pay for itself in about six months. Learn which bulb is right for you and how to dispose of CFLs.
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- Demand reduction
- Programs or technologies that reduce electric peak demand during periods of high cost electricity or shift it to non-peak periods. See also Load management.
Practical info: Demand reduction devices may be energy control or energy storage technologies. Examples include remote control of water heaters, AC compressors, and pool pump motors.
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- Demand Side Management (DSM)
- Utility activities designed to help customers use electricity, water, and gas more efficiently.
Practical info: Compared with utilities' past history, energy prices are expected to rise and availability is expected to fall. DSM programs are therefore likely to proliferate.
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- Electric grid
- Network of shared electric power. Generators feed power into a regional grid; energy is drawn on an as-needed basis. The electricity you receive is determined by a generator’s physical location.
Practical info: Power plants consume about 3.3 kilowatt-hours’ worth of fuel for every 1 kWh that reaches your home. The rest is lost along the way.
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- Energy Efficiency Measure (EEM)
- Energy-using appliance, equipment, control system, or practice whose implementation results in reduced energy use while maintaining a comparable or higher level of service.
Practical info: EEMs decrease the amount of energy used to provide a specific service or to accomplish a specific amount of work (e.g., kWh per cubic foot of refrigerator held at a specific temperature, etc).
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- Energy Efficiency Ratio (EER)
- Commonly used measurement for air conditioning equipment, often used with a seasonal energy efficiency ratio. The higher the EER number the better.
Practical info: A unit with an EER of 12 or higher may qualify for a federal tax credit.
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- Energy service company (ESCO)
- A business or organization that installs energy efficient and other demand side management measures in facilities.
Practical info: Historically operating most often in commercial, institutional and industrial areas, ESCOs have offered performance contracting (guaranteed energy savings) for decades.
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- Federal Energy Regulation Commission (FERC)
- The agency that regulates the price, terms, and conditions of energy sold through interstate commerce and all transmission services.
Practical info: Consumers pay rates based on average annual costs or other constructed prices, not real-time pricing.
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- Grid
- The layout of an electrical distribution system; a system of interconnected power lines and generators.
Practical info: The system is managed so that electricity is dispatched as needed, to meet the requirements of connected customers.
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- HCFCs
- Hydrochlorofluorocarbons are man-made refrigerants commonly found in appliances, that release chlorine and bromine in the upper atmosphere, eroding the earth’s life-preserving ozone layer.
Practical info: As of January 1, 2010 the EPA will ban on production and importing of HCFC-22 and HCFC-142B.
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- Home Energy Rating System (HERS)
- Ratings provide a standardized evaluation of a home's energy efficiency and expected energy costs.
Practical info: For an accurate assessment of your home’s energy performance, use a HERS rater. See RESNET.
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- Heating Seasonal Performance Factor (HSPF)
- A representation of the total heating output of a central air-conditioning heat pump in Btus during its normal usage period for heating, divided by the total electrical energy input in watt-hours during the same period.
Practical info: A heat pump with a high HSPF is more efficient than one with a low HSPF.
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- Kilowatt (kW)
- 1,000 watts, where a watt is a unit of electrical power calculated as the rate of energy transfer equivalent to one ampere flowing under a pressure of one volt.
Practical info: Ten 100-watt bulbs operating at full power for one hour would be 1 kWh of power.
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- Kilowatt hours (kWh)
- A measurement that appears on your electric bill to show your usage. One thousand watt-hours equal 1 kWh.
Practical info: A typical U.S. household uses approximately 27,022 kilowatt-hours of electricity per year.
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- Load
- The amount of electric power required at a specific time, or over a specific period of time, by a consumer, circuit, or electric company system.
Practical info: On a household level, the electric load is the combined total of the energy used by all electrical devices and lights in your home.
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- Load management
- see also Demand reduction. Utility activities designed to influence the timing and amount of electricity customers may use.
Practical info: Load management is the responsibility of transmission system operators. When system load approaches maximum generating capacity, operators must either find additional supply or find ways to curtail the load in order to prevent blackouts.
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- Megawatt (MW)
- One million watts of electricity.
Practical info: Most often used to describe the capacity of a power plant.
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- Non-utility supplier
- A company other than a utility that provides natural gas or electricity.
Practical info: Also known as an "independent power producer."
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- Peak demand
- The maximum level of metered electricity demand during a specified period.
Practical info: Peak demand usually occurs on hot summer days. Residential and commercial air conditioning consumes roughly 40% of total electricity during peak periods.
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- Renewable Energy Certificates (RECs)
- Tradable units that represent the commodity formed by unbundling the environmental attributes of a unit of renewable energy from its underlying electricity.
Practical info: The REC market is driven mostly by Renewable Portfolio Standards ("compliance" market).
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- Renewable Portfolio Standard (RPS)
- A requirement that a certain amount of total annual electricity sales from each retail generator must be derived from renewable sources.
Practical info: Also known as the Renewable Electricity Standard (RES), these vary by state and territory.
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- RESNET
- Residential Energy Services Network, whose mission is to improve the energy efficiency of the nation's housing stock.
Practical info: CSG is a Rater Training Provider RESNET member.
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- R-Value
- Commonly used to measure insulation, the ability to resist heat flow. Different areas of the house require different R-values, but generally speaking the higher better.
Practical info: Proper amount of insulation will help keep your house warm in the winter and cool in the summer.
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- Seasonal Energy Efficiency Ratio (SEER)
- Commonly used measurement for air conditioning equipment, often used with an energy efficiency ratio. The higher the SEER the better.
Practical info: A unit with an SEER of 14 or higher may qualify for a federal tax credit.
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- Therm
- A standard unit for measuring the amount of gas used, defined as the volume of gas needed to generate 100,000 Btu.
Practical info: Natural gas is measured by volume. The therm is the industry standard, used by most gas utilities in the U.S.
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- U-Factor
- The rate of heat loss is indicated by U-factor (U-value) of a window assembly. The lower the U-factor, the greater a window's resistance to heat flow and the better its insulating value.
Practical info: A low U-factor serves double duty – it is useful during cold days to keep the heat inside & also on hot days to keep the heat outside.
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- Watt (W)
- The unit of electrical power equal to one ampere under a pressure of one volt.
Practical info: A watt is equal to 1/746 horsepower.
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