CA CEG key terms

A structured, ongoing effort to reduce energy use and cost through planning, tracking, and improvement. It typically includes goal setting, baseline development, action plans, measurement, and management review.

A reference level of energy use, adjusted for relevant variables such as weather or production, against which savings are measured. It represents what consumption would have been without the efficiency actions.

Energy consumed per unit of output or activity, such as kWh per unit produced or kBtu per square foot. It allows comparison across time or facilities with different scales.

Annual energy consumption per unit of floor area, often expressed in kBtu per square foot per year. It is used to benchmark a building's energy performance against similar buildings.

Comparing a facility's energy performance with that of similar facilities or with historical data. It helps identify poor performers and prioritize improvement opportunities.

A systematic study of energy flows in a facility to identify how energy is used and where efficiency can be improved. Audits range from walk-through assessments to detailed engineering analyses.

A preliminary walk-through assessment that identifies obvious waste and low-cost opportunities. It relies on utility bills and visual inspection rather than detailed measurements.

A detailed energy survey that includes measurement of major end uses and engineering calculations of savings for identified measures. It provides cost and savings estimates sufficient for project prioritization.

A comprehensive engineering analysis that uses detailed data collection, modeling, and sometimes monitoring to support major capital decisions. It provides refined savings and cost estimates for specific projects.

The process of using measurements and calculations to reliably determine actual savings from an energy project. It compares post-installation energy use with an adjusted baseline.

A statistical technique that relates energy use to driving variables such as outdoor temperature or production level. It is used to adjust baselines and estimate savings in M&V.

An M&V approach that measures energy use for the entire facility using utility meters. It is suitable when savings are large and diverse across the facility.

An M&V approach that measures energy use of the specific system affected by a measure, using dedicated meters or sensors. It isolates savings from other changes in the facility.

The time required for annual savings to equal the initial project cost, calculated as cost divided by annual savings. It ignores the time value of money and savings after payback.

The total cost of owning and operating a system over its useful life, including initial cost, energy, maintenance, and replacement. It allows comparison of alternatives with different cost profiles.

The sum of future cash flows discounted to present value, minus the initial investment. A positive NPV indicates a project is expected to add value at the chosen discount rate.

The discount rate at which a project's net present value equals zero. It represents the project's expected annual return and is compared with a hurdle rate.

The rate used to convert future cash flows to present value, reflecting the time value of money and risk. A higher rate reduces the present value of future savings.

The ratio of real power (kW) to apparent power (kVA) in an alternating-current circuit. A low power factor increases current for the same real power and can incur utility penalties.

A utility charge based on the maximum rate of energy use (kW or kVA) during a billing period. Reducing peak demand can lower this charge even if total energy use is unchanged.

The ratio of average load to peak load over a period. A high load factor indicates more even energy use and often lower average cost per unit.

Voltage or current distortions at integer multiples of the fundamental frequency, caused by non-linear loads such as variable-frequency drives. They can overheat equipment and reduce power quality.

The ratio of useful heating or cooling output to energy input for a heat pump or refrigeration system. A higher COP indicates greater efficiency at given operating conditions.

The ratio of cooling output in Btu per hour to electrical input in watts at a specified condition. It is commonly used to rate unitary air-conditioning equipment.

A device that controls the speed of an electric motor by varying the frequency and voltage of its power supply. It saves energy in fans and pumps by matching output to load.

Relationships showing how flow, head, and power change with speed for fans and pumps. Power varies approximately with the cube of speed, so modest speed reductions yield large energy savings.

The ratio of useful heat output to fuel energy input, often determined by stack loss and other losses. It can be improved with tune-ups, air-fuel control, and heat recovery.

A heat exchanger that recovers heat from boiler flue gases to preheat feedwater or combustion air. It reduces fuel consumption by lowering stack losses.

A valve that automatically discharges condensate and non-condensable gases while preventing steam loss. Failed traps waste steam and degrade system performance.

The removal of water from a boiler to control dissolved solids and prevent scale. Excessive blowdown wastes energy, while insufficient blowdown risks boiler damage.

The building elements that separate conditioned interior space from the outdoors or unconditioned spaces. Its performance depends on insulation, air sealing, windows, and thermal bridging.

The overall rate of heat transfer through an assembly, expressed in Btu per hour per square foot per degree Fahrenheit. Lower U-factors indicate better insulation performance.

Uncontrolled outdoor air entering a building through cracks, gaps, and penetrations. It increases heating and cooling loads and can be reduced by air sealing.

A path of relatively high heat conductance through an otherwise insulated assembly, such as a steel stud or concrete slab. It reduces effective insulation and can cause condensation.

The installed lighting power per unit of floor area, typically in watts per square foot. It is used in energy codes to limit lighting energy use.

A device that regulates current and voltage for fluorescent and other discharge lamps. Electronic ballasts operate more efficiently than older magnetic types.

A semiconductor light source that converts electricity to light with high efficiency and long life. LEDs are widely used for energy-saving lighting retrofits.

The simultaneous production of electricity and useful thermal energy from a single fuel source. It can achieve much higher overall efficiency than separate generation.

Capturing heat that would otherwise be rejected from a process or equipment and using it for useful purposes such as preheating or space heating. It reduces purchased fuel or electricity.

The engine or turbine that drives an electric generator or mechanical equipment in a CHP or power system. Common types include reciprocating engines, gas turbines, and steam turbines.

A system that converts sunlight directly into electricity using semiconductor cells. Its output depends on irradiance, temperature, and orientation.

A device that converts direct current (DC) electricity from sources such as solar panels or batteries into alternating current (AC) for use in buildings or the grid.

The ratio of actual energy output over a period to the maximum possible output at rated capacity. It indicates how fully a generating source is utilized.

Gases such as carbon dioxide, methane, and nitrous oxide that trap heat in the atmosphere. Energy projects reduce emissions by lowering fossil fuel combustion.

The total greenhouse gas emissions caused directly or indirectly by an entity, expressed as carbon dioxide equivalent. It is used to track and report climate impact.

The amount of a pollutant or greenhouse gas released per unit of energy consumed or produced. It is used to convert energy savings into emissions reductions.

A tradable certificate representing the environmental attributes of one megawatt-hour of renewable electricity. It allows buyers to claim renewable energy use.