Resources and Glossary


Executive Summary

General Insights


Co-Benefits with Energy Savings


Energy Efficiency in Utilities


Investment and Financing








Looking to the Future



Definitions and Additional Notes for Context

50001 Ready: The U.S Department of Energy’s 50001 Ready is a self-paced program that helps a facility establish the foundational components of ISO 50001 with a step-by-step walkthrough of best practices aimed towards continuous energy performance improvement, i.e. the key ingredients to work towards ISO 50001 certification.

A-line Bulbs: the most common residential light bulb, making up about 60% of the wattage market share. (adapted from BPA)

Advanced Metering Infrastructure (AMI): infrastructure that constitutes integrated systems of smart meters, communications networks, and data management systems that enable two-way flows of information between utilities and their customers.

Benchmarking: A method to measure a building’s energy performance baseline and compare it to other similar buildings.

Better Plants Program: A Department of Energy program launched in 2011 as part of the broader Better Buildings Initiative to help improve energy consumption in the U.S. industrial sector. Companies that become Better Plants partners make a voluntary commitment to improve their energy intensity by 25% within 10 years. The program provides customized technical assistance for improving energy efficiency to Better Plants partners – which are improving their energy intensity at an average rate of 2.6% annually – as well as resources to the public on energy-saving best practices and tools. (DOE)

Building Controls, Sensors, and Submeters: Including smart thermostats, automated fault detection and diagnostics, automated shades, variable frequency drives, occupancy sensors, etc.

Carbon Intensity: The amount of carbon by weight emitted per unit of economic activity. Carbon intensity of the energy supply is measured as CO2 per unit of energy consumed. By holding carbon intensity constant, it is possible to project forward a “business as usual” scenario and track changes in the power sector that led to decarbonization.

Combined Heat and Power (CHP) Technologies: A suite of technologies that significantly enhances energy efficiency by using a single source of energy to concurrently 1) produce electricity or mechanical power and 2) recapture the waste heat to deploy as usable thermal energy for heating and/or cooling. It is considered a form of distributed energy, and is often installed at the site of consumption (e.g. industrial facilities, hospitals).

Commercial Sector: The sector consisting of service-providing facilities and equipment of businesses; federal, state and local governments; and other private and public organizations, such as religious, social, or fraternal groups. Common energy uses include space heating, water heating, air conditioning, lighting, refrigeration, cooking, and a variety of other equipment. (Adapted from EIA)

Deep Energy Retrofits: A deep energy retrofit is a major building renovation project in which site energy use intensity, including plug loads, has been reduced by at least 50% from the pre-renovation baseline with a corresponding improvement in indoor environmental quality and comfort. (Adapted from IEA)

Demand Response: Demand response enables participating customers to adjust their energy consumption in response to grid conditions, earning program participants energy bill savings and allowing utilities to avoid more costly grid management during peak periods. Strategies include reduced rates for interruptible loads, air conditioner and water heater cycling programs, and different pricing mechanisms.

Subsectors covered by Better Plants: Utilities, food, chemicals, primary metals, fabricated metal products, industrial machinery, transportation, electrical, paper/forest products.

Electricity Losses: The loss of electrical energy due to a number of different mechanisms including conductor, dielectric, reactive current, and sheath losses. Electricity losses can be mitigated with investments in technology, load management, and the reconfiguration of systems to reduce congestion; however, they cannot be entirely avoided.

Emerging Commercial Buildings (for zero net energy): Emerging zero net energy buildings have a stated goal of achieving zero energy, but do not yet have 12 months of energy use and production data to share or have not yet hit the zero energy performance target.

End-use Energy: The energy directly consumed by the user, including electricity, gasoline, natural gas, and other fuels. Does not include upstream electricity losses.

Energy Productivity: A measure of the economic output derived from each unit of energy consumed. Economy-wide energy productivity is often measured as the ratio of national GDP to primary energy consumed.

Energy Savings Performance Contracts (ESPCs): A contract between an entity, such as a federal government agency, and an energy service company (ESCO) to procure energy savings and facility improvements, paid through the project’s energy savings, with no up-front capital costs or special appropriations from Congress. (Adapted from DOE)

Energy Service Companies (ESCOs): A delivery mechanism to provide energy efficiency resources through the design, financing, installation, and operation of energy efficiency projects. Unlike other energy efficiency contractors, ESCOs link energy savings to project compensation, such as through the terms of an energy savings performance contract (ESPC).

ENERGY STAR: ENERGY STAR® is the government-backed symbol for energy efficiency, providing simple, credible, and unbiased information to consumers and businesses. The ENERGY STAR Program certifies products, single-family homes and apartment buildings, commercial buildings and industrial plants, and provides information and tools to help all these sectors make well-informed decisions. Cumulative electricity savings of the program as a whole total nearly 4,000 TWh, with 370 TWh saved in 2017 alone.  Annual savings from the ENERGY STAR program represent about 10 percent of U.S. electricity sales and associated greenhouse gas reductions are equivalent to the annual emissions of over 60 million cars.

ENERGY STAR Products: The ENERGY STAR® product certification program engages thousands of manufacturers, retailers and utilities to work with the U.S. Environmental Protection Agency to build, sell and promote products that are independently certified to meet strict specifications for high efficiency without sacrifice in performance. Americans purchase more than 300 million ENERGY STAR certified products and more than 300 million ENERGY STAR certified light bulbs annually, with an overall annual market value of more than $100 billion.  More about ENERGY STAR®.

Heat Rate: A measure of thermal efficiency in power plants, the amount of energy used by an electrical generator/power plant to generate one kilowatthour (kWh) of electricity, often measured in Btu per net kWh generated. (Adapted from EIA).

Home Energy Rating System (HERS rating): An analysis of a home’s projected energy efficiency compared to the efficiency of a “reference home” that meets the requirements of a baseline residential energy code, the 2006 International Energy Conservation Code. (For additional information, see Resnet HERS Index)

Incremental Energy Efficiency Savings: Energy savings accrued in one year corresponding to the energy efficiency measures implemented in that same year; does not count energy savings from investments made in previous years. (Adapted from ACEEE)

Industrial Sector: The sector that consists of facilities and equipment used for producing, processing, or assembling goods. Includes the following types of activity manufacturing: agriculture, forestry, fishing and hunting; mining, including oil and gas extraction; and construction. Energy uses are largely for process heating and cooling and powering machinery, with lesser amounts used for facility heating, air conditioning, and lighting. This sector also includes on-site generation of power for electricity and/or useful thermal output. (Adapted from EIA)

ISO 50001: A standard for energy management systems of the International Organization for Standardization (ISO) that requires the use of a data-driven energy management system to support a company in developing an energy policy, tracking its facility’s energy data, and utilizing the data to meet its energy goals by continuously improving energy performance. (Thomas)

Jobs (in energy efficiency): The U.S. Energy and Employment Report defines energy efficiency jobs as employment that covers “both the production and installation of energy-saving products and the provision of services that reduce end-use energy consumption.” For more information, please see The 2019 U.S. Energy and Employment Report.

LEED Certification: The LEED certification system awards points to projects according to criteria such as health of indoor spaces, waste generation, and water consumption, as well as energy related outcomes including minimizing energy consumption, implementing demand response and other grid integration strategies, and generating renewable energy. The greater the number of points awarded, the higher the LEED rating level achieved (certified, silver, gold, or platinum).

Levelized Program Administrator Cost of Saved Electricity: A measure of the cost-effectiveness of an energy efficiency program. It is the cost incurred by the program administrator for achieving electricity savings over the economic lifetime of the measures installed, amortized over that lifetime and discounted back to the first year. (Adapted from LBNL)

Levelized Total Cost of Saved Electricity: A measure of the cost-effectiveness of an energy efficiency program. Includes the costs incurred by both the program administrator and participants for achieving electricity savings over the economic lifetime of the measures installed. Value is amortized over that lifetime and discounted back to the first year. (Adapted from LBNL)

Load Aggregators: A load aggregator is a traditional load-serving entity or third-party company focused on providing demand response solutions to customers, enabling them to submit load modification or other grid service offers directly into wholesale and retail markets. (Adapted from NREL)

Load Factor (for vehicles): A measure of the capacity utilization of a transportation mode, often reported as persons per vehicle.

Low Income Home Energy Assistance Program (LIHEAP): A program administered by the U.S. Department of Health and Human Services that assists families with energy costs, including support for home energy bills, energy crises, and weatherization and energy-related minor home repairs. (Adapted from LIHEAP)

Medium- and Heavy-duty Vehicles: Larger highway transportation vehicles. Medium-duty vehicles are qualified as vehicles classes 3-6, ranging from 10,001-26,000 lbs; heavy-duty trucks include classes 7-8, weighing 26,001 lbs and above.

Model Energy Codes: A model building code is a building code that is developed and maintained by an independent organization, which can then be adopted by a state or local government.

Monetized Health Benefits: Avoided mortality, heart attacks, work loss days, asthma exacerbation, etc. associated with avoided particulate matter emissions.

Other Loads (in commercial buildings): The “Other” category includes process equipment, motors, air compressors, and other miscellaneous uses (such as televisions, personal computers, security systems, data center servers, and other devices).

Passenger Miles per Gallon of Gasoline Equivalent (pmpGGE): The energy required, in gallon gasoline equivalents, to move one passenger one mile in a given travel mode.

Peak Demand Savings: Energy savings achieved during periods of high electricity demand, which can range from one hour per year to several hours per day during high-load seasons. (Adapted from DOE)

Petroleum Violation Escrow (PVE) Funds: Oil overcharge funds from fines paid by oil companies in violation of the federal oil price caps from 1973-1981. More than half the funds were channeled through the U.S. Department of Energy’s State Energy and Weatherization Assistance Programs and the U.S. Department of Health and Human Services’ Low-Income Home Energy Assistance Program. (Adapted from AFDC)

Primary Energy: Primary energy is that which is in the form that it is first accounted for before any transformation to secondary or tertiary forms of energy. Includes energy losses due to conversion and transmission of energy, such as consumption of fuels (coal, petroleum, natural gas, nuclear, hydro, renewables), energy losses from electricity production, and electricity net imports.

Property Assessed Clean Energy Programs (PACE): A program that allows a property owner to finance the up-front cost of energy efficiency or other eligible improvements on a property and then pay the costs back over time through a voluntary assessment. (Adapted from DOE)

Range Anxiety: The perceived fear of not having access to a vehicle fueling station, usually applied to electric vehicle chargers. Range anxiety is consistently referenced as a primary barrier for consumers to purchase an electric vehicle.

Real-world Miles per Gallon: The U.S. Environmental Protection Agency’s best estimate of real-world fuel economy based on the 5-cycle test procedure that utilizes high-speed, cold start, and air conditioning tests in addition to the 2- cycle tests to provide data more representative of real-world driving. (EPA)

Residential Sector: The sector that consists of living quarters for private households, including those living in single-family, multi-family, apartment, and mobile homes. Common energy uses include consumption of electricity, natural gas, propane, or oil for a variety of uses, including powering electrical devices and appliances, heating, air conditioning, cooking, water heating and other uses. Does not include institutional living quarters. (Adapted from EIA)

States that implement Zero-Emission Vehicle mandates: CA, CT, ME, MD, MA, NJ, NY, OR, RI, VT

Smarter, More Digitalized Technologies: Technologies including smart meters and smart thermostats, smart home platforms, controls, and energy management systems; internet of things (IoT) technologies that allow cross-communication among appliances and devices to optimize a system; smart electric vehicle charging stations; and optimization protocols that allow for better integration of buildings with one another, with transportation systems, and with the grid.

Structural Changes: Major changes in the structure of production in an economy, such as a shift away from energy-intensive industries toward services.

Transportation Sector: The sector that consists of all vehicles whose primary purpose is transporting people and/or goods from one physical location to another. Includes highway vehicles such as automobiles, trucks, buses, motorcycles; as well as trains, subways, other rail vehicles, aircraft, ships, barges, and other waterborne vehicles. (Adapted from EIA)

Verified Commercial Buildings (for zero net energy): Verified and certified buildings have provided energy use and power production data to the New Building Institute to validate their zero energy status, or have been reviewed and approved by the International Living Future Institute’s zero energy certification or the U.S. Green Building Council’s LEED Zero program.

Weatherization Assistance Program (WAP): A program administered by the U.S. Department of Energy to reduce energy costs for low-income households by increasing home energy efficiency. (Adapted from WAP website)

Well-to-Wheel: Well-to-wheel analysis, also known as life cycle analysis, considers the energy impact of a vehicle running on a certain fuel including the energy consumed in fuel extraction, refinement, distribution, and use in the vehicle.

Zero Net Energy: Buildings, campuses, portfolios, or communities that, through a combination of energy efficiency and renewable energy, produce at least as much energy as they consume over the course of a year.50001 Ready: The U.S Department of Energy’s 50001 Ready is a self-paced program that helps a facility establish the foundational components of ISO 50001 with a step-by-step walkthrough of best practices aimed towards continuous energy performance improvement, i.e. the key ingredients to work towards ISO 50001 certification.