Free AEE CEM Exam Flashcards

Sets minimum energy-efficiency requirements for the design of most new commercial buildings and major renovations (excludes low-rise residential). Many state and local energy codes adopt or reference it as their baseline.

An energy management system (EnMS) standard built on a Plan-Do-Check-Act cycle. Organizations are certified to the standard for their ongoing energy-management process, not for a one-time efficiency project or a specific savings percentage.

Scope 1 is direct emissions from sources the organization owns or controls (boilers, fleet vehicles). Scope 2 is indirect emissions from purchased electricity, steam, heat, or cooling. Scope 3 covers all other indirect emissions in the value chain, such as supplier activities and employee travel.

The energy charge bills for total kWh consumed over the billing period. The demand charge bills separately for the highest kW (or kVA) the facility pulled in a short interval, because the utility must size infrastructure for that peak even if it lasts only minutes.

Billing demand is the greater of this month's actual peak or a tariff-set percentage (e.g., 80%) of the highest peak recorded in a look-back period (often the prior 11 months), so one high month can raise demand charges for months afterward.

Utilities add a surcharge when a facility's power factor drops below a tariff-specific threshold, often 0.85-0.95, because a lower power factor makes the utility supply more capacity for the same real power delivered.

Level 1 is a brief walk-through with utility bill review and low-cost recommendations. Level 2 adds a detailed engineering survey with energy-saving calculations for specific measures. Level 3 is an investment-grade audit with the detailed data and financial analysis needed to secure project financing.

Annual energy consumption divided by building floor area, in kBtu per square foot per year. Convert first: 1 kWh = 3,412 Btu; 1 therm = 100,000 Btu. EUI normalizes energy use so buildings of different sizes can be benchmarked against each other or a baseline year.

Annual energy cost divided by building floor area, in dollars per square foot per year. Unlike EUI, ECI is rate-dependent: a building can have a high EUI but only moderate ECI (or vice versa), depending on its fuel mix and utility rates.

Higher Heating Value (HHV) includes the heat released when water vapor in the combustion products condenses; Lower Heating Value (LHV) excludes it. HHV is always greater than or equal to LHV for the same fuel - equal only for fuels with no hydrogen, which produce no water vapor - and efficiency calculations must use one basis consistently.

Average demand divided by peak demand over a period. A load factor close to 1.0 means the facility runs near its peak most of the time (efficient use of capacity); a low load factor means occasional spikes drive up demand charges relative to average use.

Initial project cost divided by annual savings, in years. It is easy to calculate but ignores the time value of money, savings that change over time, and any project life beyond the payback point - so it can favor short paybacks over more profitable long-term projects.

NPV converts all future cash flows to today's dollars using a discount rate, then subtracts the initial cost. A positive NPV means the project is expected to create value beyond the required rate of return; a negative NPV means it does not.

The discount rate reflects the time value of money and the return an investor requires, used to bring future cash flows back to present value. The escalation rate is the expected annual increase in energy prices, used to project future costs or savings before discounting them.

The discount rate at which a project's NPV equals zero; accept a single project when its IRR exceeds the required hurdle rate. IRR ignores project size, and some cash-flow patterns produce multiple IRRs, so mutually exclusive projects of different sizes should be ranked by NPV instead.

The ratio of real power (kW, the power that does useful work) to apparent power (kVA, the total power the system must deliver). A power factor below 1.0 means part of that capacity is non-productive reactive power rather than usable real power.

Real power (P, kW) performs useful work. Reactive power (Q, kVAR) sustains magnetic fields in motors and transformers but does no work. Apparent power (S, kVA) is their vector sum: S squared = P squared + Q squared.

For a centrifugal pump or fan, flow scales directly with speed, pressure (head) scales with speed squared, and power scales with speed cubed. Cutting speed by half theoretically cuts power to about one-eighth.

The ratio of a motor's actual output to its rated (nameplate) output. Motors run most efficiently in roughly the 50%-100% load range; a motor that is greatly oversized for its job runs lightly loaded, at reduced efficiency and power factor, wasting capacity and energy.

kVAR needed = kW × (tan θ1 − tan θ2), where θ = arccos(PF). Example: raising 500 kW from 0.80 to 0.95 PF needs about 500 × (0.750 − 0.329) ≈ 211 kVAR. Real power (kW) is unchanged; apparent power (kVA) and current both drop.

Lumens measure the total light output of a source. Footcandles measure illuminance - how much of that light actually lands on a work surface, one footcandle equaling one lumen per square foot. The same lamp can produce very different footcandles depending on fixture design, mounting height, and room reflectance.

Light output divided by electrical power input, expressed in lumens per watt (lm/W). It lets you compare how efficiently different lamp technologies convert electricity into visible light, independent of how much total light a space needs.

Describes how accurately a light source renders object colors versus a reference light of similar color temperature. CRI tops out at 100 but has no fixed floor - some sources score negative. It reflects color quality only, not efficacy or energy use.

COP is a dimensionless ratio of useful cooling output to work input. EER = 3.412 × COP (Btu/h output per watt input). kW/ton = 12 ÷ EER = 3.517 ÷ COP - so a COP of 5.0 equals an EER near 17.1, or about 0.70 kW/ton. Lower is better for kW/ton; higher is better for COP and EER.

Brings in extra outside air to cool a building for free when outdoor conditions allow, cutting or eliminating mechanical cooling. Needs correctly sized and sequenced dampers and controls, or it can pull in humid or cold air and waste energy instead.

A measure of how much and how long outdoor temperature stayed above or below a base temperature (commonly 65°F). Heating degree days (HDD) estimate heating loads: seasonal envelope loss (Btu) ≈ U × A × HDD × 24, divided by heating-system efficiency for fuel input. Cooling degree days work the same way for cooling.

R-value measures thermal resistance - how well a material resists heat flow, so higher is better insulation. U-value is its reciprocal (U = 1/R), measuring thermal conductance, so a lower U-value means a better-insulated assembly.

A CAV system supplies a fixed airflow and varies only supply air temperature to meet zone loads. A VAV system holds temperature closer to constant and instead varies the volume of air delivered to each zone, which lets fan power drop with demand and generally uses less energy at part load.

A chart that plots the interrelated properties of moist air - dry-bulb temperature, wet-bulb temperature, relative humidity, humidity ratio, and enthalpy - so an energy manager can find any other property once two are known, and evaluate cooling, heating, or dehumidification processes graphically.

It expresses total electrical input (chiller, plus often pumps and cooling-tower fans) per ton of cooling delivered, so a rising kW/ton over time signals fouled heat-exchanger surfaces, low refrigerant charge, or control problems - even if the chiller is still meeting the cooling load.

Proportional (P) control alone leaves a permanent offset between setpoint and actual value. Adding integral action (PI) drives that offset to zero over time. Adding derivative action (PID) reacts to the rate of change as well, improving response to fast disturbances but requiring more careful tuning.

A control strategy that uses indoor and outdoor temperature (and sometimes building thermal mass data) to calculate the latest possible time to start HVAC equipment before occupancy and the earliest time to stop it before the space is vacated, while still meeting comfort requirements at those boundary times.

Setback lowers (or raises) a zone's temperature setpoint during unoccupied hours to save energy. Reset instead adjusts a setpoint - such as supply-air or hot-water temperature - based on a variable like outdoor temperature or zone demand, so the system produces only as much heating or cooling capacity as conditions require.

Software that continuously compares building automation system data against expected performance rules or models to flag equipment operating abnormally - such as simultaneous heating and cooling, or a stuck damper - so staff can correct energy-wasting faults before they persist for months.

Full storage meets the entire on-peak cooling load from storage, with the chiller off during on-peak hours. Partial storage keeps the chiller running on-peak too - either at constant output all day (load leveling) or reduced output (demand limiting) - with storage covering the rest of the load.

The percentage of energy put into a storage system that can later be retrieved as usable output, after accounting for charging, discharging, and standby losses. A lower round-trip efficiency means more of the stored energy - and its associated cost - is lost rather than delivered.

Periodically draining a controlled amount of boiler water to remove dissolved solids that concentrate as steam is generated. Too little blowdown lets solids build up and cause scale or carryover; too much wastes hot water and treatment chemicals, so it must be balanced against water quality targets.

A steam trap is meant to release condensate and air while holding back live steam. A trap that fails open blows live steam continuously into the condensate system - a large, often unnoticed energy loss - while a trap that fails closed backs up condensate and can cause water hammer or heating problems.

A CHP system captures the heat that a conventional power plant or generator would otherwise reject as waste and puts it to use for space heating, process heat, or absorption cooling, so more of the fuel's energy content ends up as useful output instead of being discarded.

The ratio of energy a source actually produced over a period to what it would produce running at full rated output the whole time. A solar or wind asset can be highly efficient but have a low capacity factor, because its resource is intermittent.

Generating compressed air is inherently inefficient - only a small fraction of the electrical energy fed to the compressor ends up as usable pneumatic work, with most lost as heat - so leaks, oversized pressure, and inefficient end uses waste a disproportionate amount of electricity for the work delivered.

Throttling a valve or damper reduces flow by adding artificial resistance while the motor keeps running near full speed and power. A VFD instead slows the motor to match the process demand, which - per the affinity laws - cuts power consumption much more than throttling does for the same flow reduction.

The difference between the cold water leaving the tower and the ambient wet-bulb temperature. A rising approach temperature over time (for the same conditions) signals fouled fill, poor air distribution, or scaling - reduced tower performance that forces the chiller to work harder to reject the same heat load.

Commissioning verifies that a new building's systems are installed and operating as designed. Retrocommissioning applies that same verification process to an existing building that was never formally commissioned. Recommissioning repeats the process on a building that was already commissioned, to recapture performance that drifted over time.

Preventive maintenance follows a fixed schedule (such as replacing a filter every three months) regardless of actual equipment condition. Predictive maintenance instead uses monitored data - vibration, temperature, oil analysis - to trigger service based on the equipment's actual condition, aiming to avoid both unnecessary service and unexpected failure.

Whether a project's measured energy savings continue at the same level in later years, rather than only in the first measurement period. Savings can erode as controls drift, filters clog, or occupants override setpoints, which is why ongoing monitoring - not just a one-time verification - matters for long-lived measures.

An extension of one-time retrocommissioning that keeps using trend data and automated fault detection to catch performance drift as it happens, rather than waiting years for the next scheduled commissioning study to find problems that accumulated in the meantime.

Deliberately forcing a system through its full range of operating conditions and sequences - not just observing it in whatever mode it happens to be running - to confirm that controls, interlocks, and equipment respond correctly in every mode, including rarely-occurring modes such as an emergency power failure sequence.

In a guaranteed-savings ESPC, the ESCO guarantees a savings level and reimburses shortfalls, while the customer usually arranges financing. In a shared-savings ESPC, the ESCO arranges financing too, so it carries both performance risk and credit risk, and the two parties split the savings.

Option A (retrofit isolation) measures the key parameter and stipulates the rest; Option B (retrofit isolation) measures all parameters. Option C (whole facility) uses utility meter data for the entire building. Option D (calibrated simulation) applies when baseline or post-retrofit data are missing.