Active Efficiency and the Collaborative

Active Efficiency is a key enabler for creating an equitable, adaptable,
and decarbonized energy system.

As energy efficiency enters the digital age, we must coalesce around a shared vision that integrates well-established energy efficiency approaches with the capabilities of smart and connected technologies, distributed energy resources, and key decarbonization strategies. 


Active Efficiency

The optimized use of energy by integrating the benefits of traditional energy efficiency measures with the opportunities presented by digital technologies.

Advanced metering infrastructure (AMI)

An integrated system of smart meters, communications networks, and data management systems that enables two-way communication between utilities and customers. (DOE)

Ancillary services

Services necessary to support the transmission of capacity and energy from generation resources to consumers, while maintaining the reliable operation of the transmission system.

Beneficial electrification

The application of electricity to end-uses where doing so satisfies at least one of the following conditions without adversely affecting the others: saving consumers money over time; reducing greenhouse gas emissions; improving product quality or consumer quality of life; and/or fostering a more robust and resilient grid. (BEL)

Building system

A combination of equipment, operations, controls, accessories, and means of interconnection that use energy to perform a specific function.
(Alliance to Save Energy)

Central utility plant

A central utility plant provides heating, cooling, and/or electricity. The equipment at a central utility plant may include chillers, boilers, power generators, and pumps.

Commercial sector

An energy-consuming sector that consists 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. The commercial sector includes institutional living quarters. Note: This sector includes generators that produce electricity and/or useful thermal output primarily to support the activities of the above-mentioned commercial establishments. (EIA)

Cooling degree days

A measure of how hot the temperature was on a given day or during a period of days. (EIA)

Demand flexibility

The ability to shift electricity demand across hours of the day to when power is abundant and cheap, while maintaining the same or better quality with a lower cost. (RMI)

Demand response (DR)

Instances when consumers reduce or shift their electricity usage during peak periods in response to time-based rates or other forms of financial incentives.

Demand-side management programs

Programs designed by electric utilities that aim to encourage consumers to modify their level and pattern of electricity usage. (EIA)

Distributed energy resource (DER)

A resource sited close to customers that can provide all or some of their immediate electric and power needs and can also be used by the system to either reduce demand (such as energy efficiency) or provide supply to satisfy the energy, capacity, or ancillary service needs of the distribution grid. Examples of DERs include solar photovoltaics, wind, combined heat and power (CHP), energy storage, demand response, electric vehicles, microgrids, and energy efficiency. (DOE)

Emissions efficiency

A metric that reflects emissions created per unit of output of an energy-consuming service. (RAP/BEL)

Energy efficiency

The ongoing reduction in energy use to provide the same or improved function. (DOE)

Evaluation, measurement & verification (EM&V)

A set of processes (listed below in the order they are typically conducted) to determine project and/or program energy savings impacts. (NRDC)

  • Measurement – This step estimates the amount of energy and/or demand savings resulting from the implementation of an energy efficiency measure. There are several common methods of estimating savings, involving a combination of physical measurements, engineering calculations, statistical analysis, and/or computer simulation of buildings. Because energy efficiency savings are the difference between actual usage and a counterfactual baseline, “measured” savings are actually all estimations, with varying levels of confidence around the prediction.
  • Verification – Program staff or third parties verify (often with on-site field inspection) that energy efficiency measures have been implemented and are operating properly. This may entail counting the number of measures that have been implemented.
  • Evaluation – After a given program or portfolio is completed, evaluations analyze its performance and operation, including total energy savings relative to predictions, impact on markets, and cost-effectiveness.

Grid-interactive efficient building (GEB)

An energy-efficient building with smart technologies characterized by the active use of DERs to optimize energy use for grid services, occupant needs and preferences, and cost reductions in a continuous and integrated way. (DOE)

Heating degree days

A measure of how cold the temperature was on a given day or during a period of days. (EIA)

Load shifting/shaping

The ability to change the timing of electricity use to minimize demand during peak periods and/or to take advantage of the cheapest time-of-use differences in electricity prices. (DOE)

Performance-based utility program

A utility energy efficiency program that delivers energy savings and/or demand flexibility by providing incentives for measured and verified energy and/or demand reductions over a specified time period.


The degree to which the performance of the electric grid results in power being delivered to consumers within accepted standards and in the amount desired.

Residential sector

An energy-consuming sector that consists of living quarters for private households. Common uses of energy associated with this sector include space heating, water heating, air conditioning, lighting, refrigeration, cooking, and running a variety of other appliances. The residential sector excludes institutional living quarters. (EIA)

Responsive customers

Customers that change their electricity use in response to wholesale electricity prices or other signals.

Smart loads

Loads that follow the power generation profile to regulate its energy use in a way that supports the stability of the grid.

    Where definitions have been adapted from other sources, links are provided to the original source in parenthesis.