AEE Certified Energy Manager (CEM) key terms

Sets minimum energy efficiency requirements for the design and operation of most commercial and high-rise residential buildings, covering envelope, HVAC, service water heating, power, lighting, and other equipment.

A model energy code published by the International Code Council that sets minimum efficiency requirements for residential and commercial buildings; local jurisdictions adopt it, often by reference, as enforceable law.

Standard specifying minimum ventilation rates and indoor air quality requirements for commercial and institutional buildings; its outdoor-air rates directly affect heating, cooling, and fan energy use.

A code compliance route in which each building component must individually satisfy listed minimum requirements, such as insulation levels or lighting wattage limits, without relying on whole-building energy modeling trade-offs.

The ratio of real power in kilowatts to apparent power in kilovolt-amperes in an AC circuit. Low power factor raises current for the same useful work, increasing losses and often triggering utility penalties.

A monthly utility charge based on the highest rate of energy use recorded during a billing period, usually averaged over a short interval such as 15 minutes; reducing peaks lowers this charge.

An electric motor efficiency designation defined by NEMA MG 1 that exceeds prior standard-efficiency levels; many codes require premium-efficiency motors for general-purpose applications in new and replacement installations.

An electronic device that varies the speed of an AC motor by adjusting the frequency and voltage supplied to it, so fan and pump output tracks load instead of running at constant full speed.

A quality-focused process for verifying that building systems and assemblies are designed, installed, tested, and able to operate and be maintained according to the owner's requirements and the design intent.

A systematic process applied to existing buildings that were not newly commissioned, to identify and correct operational deficiencies and tune controls and equipment so systems perform as intended or better.

A documented test in which a system is operated under staged conditions to demonstrate that it performs its intended function and interacts correctly with related systems and controls.

Total annual site energy use of a building divided by its gross floor area, typically stated in kBtu per square foot per year or kWh per square meter per year; a convenient benchmark for comparing similar buildings.

An energy survey with detailed analysis of energy use and costs broken down by end use, plus identification and rough costing of conservation measures; more thorough than a walk-through but short of investment-grade analysis.

A diagnostic test that mounts a calibrated fan in an exterior doorway to pressurize or depressurize a building, measuring envelope air leakage and helping locate infiltration paths.

An inspection technique using thermal cameras to visualize surface temperature differences, revealing insulation gaps, air leakage, moisture, and overheating electrical connections that are invisible to the naked eye.

On-site generation of electricity and useful thermal energy from a single fuel source, such as a gas turbine or engine, with recovered heat used for process loads, space heating, or absorption cooling.

The fuel energy input required to produce one unit of useful output, typically Btu per kWh for generators or a dimensionless ratio for boilers; a lower heat rate means higher efficiency.

The ratio of energy actually produced by a generating unit over a period to the energy it would have produced at rated output continuously; wind and solar typically show low values compared with dispatchable plants.

A tradable certificate representing the environmental attributes of one megawatt-hour of electricity generated from renewable sources, used to claim renewable use and to comply with portfolio standards.

The ratio of useful heating or cooling output to energy input expressed in consistent units; a COP of 4 delivers four units of cooling per unit of electricity, roughly equal to 13.6 EER.

A control strategy that uses cool outdoor air instead of mechanical cooling when outdoor conditions permit, by modulating outdoor-air and relief dampers to bring outside air into the building.

An air distribution system in which the supply fan delivers a varying volume of air at a roughly constant temperature, and zone boxes throttle airflow to match each zone's changing load.

Electrical demand in kilowatts divided by cooling output in tons of refrigeration; lower values are better, with efficient machines typically near 0.5 to 0.6 kW per ton at design conditions.

A standard data communication protocol, ASHRAE Standard 135, that lets building automation devices from different manufacturers exchange data over a common network, supporting interoperability and competitive bidding.

A control algorithm whose output combines proportional, integral, and derivative responses to the difference between setpoint and measured value, giving stable control of temperature, pressure, and flow.

The range of values around a setpoint within which no control action is taken, preventing equipment from cycling rapidly between heating and cooling; wider deadbands generally save energy.

A ventilation strategy that modulates outdoor air intake in response to measured occupancy, often using carbon dioxide sensors, so spaces get needed outdoor air without over-ventilating and wasting conditioning energy.

A system that stores cooling or heating capacity, usually in water, ice, or phase-change material, during low-cost or off-peak periods and discharges it later to meet building loads.

A thermal storage approach that builds ice in tanks or on coils using a chiller at night, then melts it during the day to supply chilled water, shifting electric demand to off-peak hours.

Deliberately reducing facility electric demand during high-cost or constrained periods, often through storage discharge, load shedding, or on-site generation, to cut demand charges and capacity costs.

The natural layering of a stored fluid by temperature, with warmer, lighter water at the top and cooler, denser water below; good stratification preserves usable capacity in chilled or hot water storage tanks.

Installed lighting wattage in a space divided by its floor area, expressed in watts per square foot; energy codes set maximum allowed values used in prescriptive and whole-building compliance calculations.

The delivered light output of a complete luminaire in lumens divided by the power it draws in watts, including driver or ballast losses; the key metric for comparing lighting products.

The ratio of light output from a fluorescent lamp operated on a given ballast to the output obtained with a standard reference ballast; it scales both lumen output and input wattage.

A control strategy that dims or switches electric lighting in response to available daylight measured by photosensors, maintaining target illuminance while cutting lighting energy and cooling load.

A device that detects whether a space is occupied, using passive infrared, ultrasonic, or both, and turns lighting or ventilation off or down when the area is empty.

A contracting arrangement in which an energy services company finances and installs efficiency improvements and is repaid from measured savings, under guaranteed or shared-savings terms set in the contract.

An industry framework published by EVO defining common measurement and verification options, boundary definitions, baseline adjustment, and reporting conventions so claimed energy savings can be verified consistently and transparently.

The measured or modeled energy use during a defined pre-retrofit period, adjusted for routine factors such as weather, occupancy, and production, against which post-installation consumption is compared to determine savings.

A measurement and verification option in which savings for an individual measure are determined by field measurement of that measure's energy use, separate from the rest of the facility, using short-term or continuous metering.