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AEE Certified Energy Manager (CEM) study materials
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AEE Certified Energy Manager (CEM) practice questions

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Question 1Codes and Standards

ASHRAE Standard 90.1 applies to which of the following buildings?

  1. A two-story duplex apartment
  2. A three-story multifamily residence
  3. A one-story single-family house
  4. A three-story office tower Correct answer.

Explanation

ASHRAE 90.1 covers buildings except low-rise residential buildings, which are defined as residential buildings three stories or fewer above grade. Single-family houses, duplexes, and low-rise multifamily buildings fall under ASHRAE 90.2 instead. A three-story office tower is a commercial building and therefore within 90.1 scope.

Question 2Codes and Standards

The International Energy Conservation Code (IECC) is developed and published by which organization?

  1. The National Fire Protection Association
  2. The American Society of Heating, Refrigerating and Air-Conditioning Engineers
  3. The U.S. Green Building Council
  4. The International Code Council Correct answer.

Explanation

The IECC is a model energy code maintained and published by the International Code Council. ASHRAE publishes Standard 90.1, which is a separate energy standard often referenced as an alternative compliance path. NFPA and USGBC publish fire codes and green building rating systems, respectively.

Question 3Codes and Standards

ASHRAE Standard 62.1 addresses which subject?

  1. Energy efficiency in new commercial buildings
  2. Thermal comfort in occupied spaces
  3. Ventilation and indoor air quality Correct answer.
  4. Energy use in existing buildings

Explanation

ASHRAE 62.1 is titled Ventilation for Acceptable Indoor Air Quality and sets minimum ventilation rates and other IAQ requirements. Thermal comfort is addressed by Standard 55, and energy efficiency in new commercial buildings by Standard 90.1. Standard 100 addresses existing buildings.

Question 4Codes and Standards

ASHRAE Standard 55 sets requirements for which of the following?

  1. Motor efficiency test methods
  2. Energy performance of data centers
  3. Human thermal comfort conditions Correct answer.
  4. Residential ventilation requirements

Explanation

ASHRAE 55 defines the ranges of indoor thermal environmental conditions that are acceptable to a specified percentage of occupants. It addresses temperature, humidity, air speed, radiant asymmetry, and clothing and metabolic factors. It does not set ventilation rates, motor efficiency, or data center energy requirements.

Question 5Codes and Standards

In ASHRAE 90.1, lighting power density for a building is normally expressed in which units?

  1. Kilowatt-hours per square foot
  2. Watts per square foot Correct answer.
  3. Footcandles per square meter
  4. Lumens per watt

Explanation

Lighting power density (LPD) is the connected lighting power divided by the floor area of the space or building, expressed in watts per square foot in inch-pound units. Lumens per watt is efficacy, and footcandles measure illuminance. Kilowatt-hours per square foot measures annual energy use, not connected power density.

Question 6Codes and Standards

The Energy Independence and Security Act of 2007 established efficiency standards that phased out which lamps?

  1. T8 linear fluorescent tube lamps
  2. Integrated LED downlight fixtures
  3. Standard incandescent bulbs Correct answer.
  4. Ceramic metal halide arc lamps

Explanation

EISA 2007 set maximum wattage standards for general service incandescent lamps in common wattages, which effectively phased out the least efficient standard incandescent bulbs. The law did not phase out fluorescent, metal halide, or LED products. It also addressed other efficiency measures, including federal building performance.

Question 7Codes and Standards

Under ASHRAE 90.1, the requirement for an air-side economizer on a comfort cooling system depends primarily on which two factors?

  1. Cooling capacity and climate zone Correct answer.
  2. Chiller efficiency and refrigerant type
  3. Fan power and duct static pressure
  4. Building height and occupancy type

Explanation

ASHRAE 90.1 Section 6.5.1 requires economizers based on the cooling system capacity and the ASHRAE climate zone in which the building is located. Larger systems in cooler climate zones are more likely to require economizers, while some climate zones have exceptions. Fan power, chiller efficiency, and building height do not trigger the economizer requirement.

Question 8Codes and Standards

In the ASHRAE 62.1 Ventilation Rate Procedure, the breathing zone outdoor airflow rate Vbz is calculated by which expression?

  1. Rp x Az + Ra x Pz
  2. Ra x Pz + Rp x Az
  3. Rp x Pz + Ra x Az Correct answer.
  4. Pz x Az / (Rp + Ra)

Explanation

The breathing zone outdoor airflow is the sum of the people component and the area component: Vbz = Rp x Pz + Ra x Az. Rp is the outdoor airflow rate required per person, Pz is the zone population, Ra is the rate per unit area, and Az is the zone floor area. The other expressions incorrectly combine or divide these terms.

Question 9Codes and Standards

ISO 50001 contains requirements for which of the following?

  1. A building energy code
  2. A lighting power budget
  3. A refrigerant management plan
  4. An energy management system Correct answer.

Explanation

ISO 50001 specifies requirements for establishing, implementing, maintaining, and improving an energy management system. It is built on the Plan-Do-Check-Act cycle and requires an energy policy, energy objectives, and action plans. It is not a prescriptive building code or a lighting or refrigerant regulation.

Question 10Codes and Standards

ASHRAE 90.1 requires automatic lighting shutoff controls for interior lighting in buildings larger than what floor area?

  1. 10,000 square feet
  2. 2,000 square feet
  3. 25,000 square feet
  4. 5,000 square feet Correct answer.

Explanation

ASHRAE 90.1 Section 9.4.1.1 requires automatic lighting shutoff controls in buildings larger than 5,000 square feet. The controls may be time-switch based, occupancy based, or another approved automatic method. Smaller buildings are not subject to that specific automatic shutoff requirement.

Question 11Codes and Standards

In EPA's ENERGY STAR Portfolio Manager, a 1-100 energy score of 75 for an office building indicates which of the following?

  1. It has met 75% of certification requirements
  2. It uses 75% of the energy of an average building
  3. It uses 75% less energy than the national median
  4. It ranks in the top 25% of similar buildings Correct answer.

Explanation

The ENERGY STAR score compares a building's source energy use with that of similar buildings nationwide; a score of 75 means it performs better than 75% of its peers, placing it in the top quartile. A score of 50 represents median performance. A score of 75 is one eligibility criterion for ENERGY STAR certification, but other criteria must also be met.

Question 12Codes and Standards

ASHRAE Standard 100 provides requirements for which of the following?

  1. Energy efficiency in low-rise residential buildings
  2. Ventilation for acceptable indoor air quality
  3. Energy efficiency in existing buildings Correct answer.
  4. Thermal comfort in occupied spaces

Explanation

ASHRAE Standard 100 is the energy efficiency standard for existing buildings. It addresses operation, maintenance, and retrofit measures to improve energy performance over time. New commercial buildings are covered by 90.1, and low-rise residential buildings by 90.2.

Question 13Codes and Standards

California's Title 24, Part 6 contains which of the following?

  1. Energy efficiency standards Correct answer.
  2. Voluntary green rating requirements
  3. Plumbing fixture requirements
  4. Fire and life safety requirements

Explanation

Title 24, Part 6 is the California Energy Code, which contains the state's building energy efficiency standards. It covers residential and nonresidential energy requirements and is updated on a three-year cycle. Fire requirements are in Part 9, and plumbing requirements are in Part 5.

Question 14Codes and Standards

ASHRAE Standard 189.1 provides requirements for which type of building?

  1. High-performance green buildings Correct answer.
  2. Health care facilities only
  3. Existing buildings only
  4. Low-rise residential buildings of three stories or fewer

Explanation

ASHRAE 189.1 is the Standard for the Design of High-Performance Green Buildings and is often used as the technical basis for the International Green Construction Code. It covers site, water, energy, materials, and indoor environmental quality beyond the minimum energy code. It applies broadly to new construction and major renovations.

Question 15Codes and Standards

ASHRAE 90.1 limits HVAC fan system power primarily by which method?

  1. A fixed 5 horsepower cap per air handler
  2. A maximum W/cfm based on system type Correct answer.
  3. A percentage of connected chiller capacity
  4. A maximum duct static pressure of 2 in. w.c.

Explanation

ASHRAE 90.1 Section 6.5.3 limits fan system power in watts per cubic foot per minute of supply air, with the allowable value depending on the system type. The limitation is intended to encourage efficient fan and duct design. It does not impose a fixed horsepower cap or a universal duct static pressure limit.

Question 16Codes and Standards

ASHRAE 62.1 demand-controlled ventilation typically modulates outdoor air based on which sensor?

  1. A differential temperature sensor
  2. A carbon dioxide sensor Correct answer.
  3. A duct static pressure sensor
  4. A relative humidity sensor

Explanation

Demand-controlled ventilation commonly uses carbon dioxide concentration as an indicator of occupancy and adjusts outdoor air delivery accordingly. It is permitted where the zone population varies and the design maintains the required minimum rates. Static pressure, humidity, and temperature sensors serve other control functions.

Question 17Codes and Standards

In ASHRAE 90.1 Appendix G, the baseline building performance is determined by simulating the proposed design at how many orientations?

  1. Four orientations Correct answer.
  2. Eight orientations
  3. Two orientations
  4. One orientation

Explanation

Appendix G requires the baseline building model to be rotated to the four cardinal orientations, and the average of the four results is used as the baseline performance. This reduces sensitivity to the actual building orientation. The proposed design is modeled in its actual orientation.

Question 18Codes and Standards

Under ASHRAE 62.1, the Indoor Air Quality Procedure differs from the Ventilation Rate Procedure in which way?

  1. It prescribes fixed outdoor airflow rates per person
  2. It removes the requirement for outdoor air
  3. It relies on contaminant limits Correct answer.
  4. It applies only to residential occupancies

Explanation

The Indoor Air Quality Procedure is a performance-based approach that limits known contaminants and maintains acceptable perceived air quality. The Ventilation Rate Procedure is prescriptive and uses tabulated outdoor airflow rates per person and per unit area. Both procedures require adequate outdoor air and apply to nonresidential occupancies covered by 62.1.

Question 19Codes and Standards

Which ASHRAE 90.1 compliance path allows trade-offs among envelope, lighting, and HVAC systems?

  1. The energy cost budget method Correct answer.
  2. The envelope trade-off option only
  3. The mandatory provisions only
  4. The prescriptive path only

Explanation

The Energy Cost Budget method compares the proposed design's annual energy cost with that of a budget building, allowing trade-offs across envelope, lighting, and HVAC systems. The prescriptive provisions in Sections 5 through 10 generally must be met without cross-system trade-offs, except for the limited envelope trade-off option. The mandatory provisions apply regardless of the compliance path.

Question 20Codes and Standards

For commercial buildings, the IECC generally permits compliance by showing that the building meets which ASHRAE standard as an alternative?

  1. ASHRAE 90.1 Correct answer.
  2. ASHRAE 55
  3. ASHRAE 62.1
  4. NFPA 101

Explanation

The IECC commercial provisions allow compliance with ASHRAE 90.1 as an alternative to the IECC's own commercial requirements. A building designed to meet 90.1 is generally deemed to satisfy the IECC commercial energy provisions. Standards 62.1 and 55 address ventilation and thermal comfort rather than the energy code alternative.

Question 21Electrical Power Systems and Motors

Power factor in an AC electrical system is defined as which ratio?

  1. Reactive power divided by real power
  2. Real power divided by reactive power
  3. Real power divided by apparent power Correct answer.
  4. Apparent power divided by real power

Explanation

Power factor is the cosine of the angle between voltage and current, numerically equal to real power (kW) divided by apparent power (kVA). Inductive loads such as motors draw lagging reactive power, which drives the ratio below unity. Utilities penalize low power factor because the extra current heats conductors without delivering useful work.

Question 22Electrical Power Systems and Motors

The synchronous speed of a polyphase induction motor is given by which expression, where f is supply frequency in hertz and P is the number of poles?

  1. f/(120P)
  2. 120f/P Correct answer.
  3. 60f/P
  4. P/(120f)

Explanation

Synchronous speed in revolutions per minute equals 120 times the frequency divided by the number of poles. The constant 120 combines the conversion from hertz to revolutions per minute with the fact that a pole pair is completed every half cycle. Actual rotor speed is a few percent lower because of slip.

Question 23Electrical Power Systems and Motors

An electric bill shows both a kilowatt-hour charge and a kilowatt demand charge. The demand charge is based on which quantity?

  1. Peak power demand reached in the period Correct answer.
  2. Average power measured across the period
  3. Total energy consumed over the whole period
  4. Reactive energy supplied to the facility

Explanation

The demand charge recovers the cost of capacity the utility must hold available, so it is set by the highest rate of power use recorded in the billing period. Energy charges recover fuel and variable costs and are based on accumulated kilowatt-hours. Demand is normally integrated over a short window such as 15 or 30 minutes.

Question 24Electrical Power Systems and Motors

A variable frequency drive controls the speed of an AC induction motor primarily by varying which parameter?

  1. Supply frequency Correct answer.
  2. Number of motor poles
  3. Supply voltage magnitude only
  4. Stator winding resistance

Explanation

The inverter stage of a drive changes the frequency of the voltage applied to the motor, and synchronous speed is directly proportional to frequency. Volts-per-hertz control adjusts voltage along with frequency so that air-gap flux stays essentially constant. Pole count and winding resistance are fixed by the motor design.

Question 25Electrical Power Systems and Motors

In a transformer, the copper (winding) losses vary in proportion to which quantity?

  1. The square of the load current Correct answer.
  2. The load power factor
  3. The load current directly
  4. The square root of the applied voltage

Explanation

Winding loss is resistive loss, equal to current squared times resistance, so it rises with the square of load current and is called a variable or load loss. Core loss from hysteresis and eddy currents is essentially constant at rated voltage and frequency. Maximum efficiency occurs where the two loss components are equal.

Question 26Electrical Power Systems and Motors

Load factor for a facility is defined as which ratio?

  1. Peak demand divided by average load
  2. Average load divided by peak demand Correct answer.
  3. Connected load divided by peak demand
  4. Peak demand divided by connected load

Explanation

Load factor is average load divided by peak demand over the same period, and it measures how fully the peak capacity is used. A low load factor means capital-intensive capacity sits idle much of the time. It is distinct from demand factor, which relates peak demand to connected load.

Question 27Electrical Power Systems and Motors

A 500 kW load operates at 0.80 power factor. What capacitor rating is required to raise the plant power factor to 0.95?

  1. 286 kVAr
  2. 164 kVAr
  3. 375 kVAr
  4. 211 kVAr Correct answer.

Explanation

Required reactive compensation equals real power times the difference between the tangents of the initial and target power factor angles. For 500 kW: 500 x (0.750 - 0.329), which is about 211 kVAr. Adding capacitors supplies reactive power locally and does not change the kW demand of the load.

Question 28Electrical Power Systems and Motors

A balanced three-phase motor draws 460 V, 60 A at 0.85 power factor. What is its electrical input power?

  1. 23.5 kW
  2. 34.5 kW
  3. 47.8 kW
  4. 40.6 kW Correct answer.

Explanation

Three-phase input power is the square root of three times line voltage times line current times power factor. Substituting gives 1.732 x 460 x 60 x 0.85, or roughly 40.6 kW. Ignoring the power factor would yield apparent power in kVA rather than real power.

Question 29Electrical Power Systems and Motors

Which of the following best describes the function of a solid-state soft starter?

  1. It converts DC power to AC for the motor
  2. It corrects the motor power factor to unity
  3. It maintains constant motor speed regardless of load
  4. It limits inrush current during acceleration Correct answer.

Explanation

A soft starter uses thyristors to ramp the applied voltage during acceleration, which reduces starting current and torque compared with a direct-on-line start. It is bypassed once the motor reaches full speed and does not regulate running speed. Continuous speed control requires a variable frequency drive instead.

Question 30Electrical Power Systems and Motors

A 4-pole, 60 Hz induction motor has a nameplate full-load speed of 1750 rpm and is measured at 1762 rpm. What is its approximate load?

  1. About 50%
  2. About 95%
  3. About 76% Correct answer.
  4. About 30%

Explanation

Slip is the gap between synchronous speed and actual rotor speed; for 4 poles at 60 Hz the synchronous speed is 1800 rpm. Full-load slip is 1800 minus 1750, or 50 rpm, while measured slip is 1800 minus 1762, or 38 rpm. Load is therefore roughly 38 divided by 50, about 76% of rating.

Question 31Electrical Power Systems and Motors

Voltage unbalance on a three-phase induction motor primarily causes which adverse effect?

  1. Higher shaft speed and increased windage losses
  2. Lower starting torque and reduced inrush current
  3. Negative-sequence current that heats the rotor Correct answer.
  4. Higher power factor and reduced line current

Explanation

An unbalanced supply resolves into positive- and negative-sequence components; the negative-sequence component rotates against the rotor and induces currents near twice line frequency. Those currents concentrate in the rotor and cause rapid heating and reduced insulation life. Motors are therefore derated for unbalance well before 5%.

Question 32Electrical Power Systems and Motors

When a standard-efficiency induction motor is replaced with a NEMA Premium efficiency unit, the savings are greatest under which operating condition?

  1. Long idle periods with the motor energized
  2. Continuous full-load operation for many hours Correct answer.
  3. Intermittent duty of under one hour per day
  4. Frequent starting and stopping at light load

Explanation

Savings equal the efficiency improvement multiplied by the energy the motor actually consumes, so they are largest for motors that run many hours near rated load. Light, intermittent, or idle duty leaves little energy to save and stretches the simple payback past the motor's life. High-hour, high-load motors are therefore screened first.

Question 33Electrical Power Systems and Motors

A tariff contains a 12-month ratchet of 80% of the highest billing demand. If the July peak was 400 kW and January's peak is 250 kW, what demand is billed in January?

  1. 320 kW Correct answer.
  2. 400 kW
  3. 200 kW
  4. 250 kW

Explanation

A ratchet clause bills the greater of the current period's demand or a stated percentage of the highest demand over the preceding months. Here 80% of 400 kW equals 320 kW, which exceeds the January peak of 250 kW. The ratchet is designed to recover fixed capacity costs from customers whose peaks drop seasonally.

Question 34Electrical Power Systems and Motors

Six-pulse variable frequency drives are a significant source of which harmonic orders in a facility's electrical system?

  1. 3rd and 9th
  2. 2nd and 3rd
  3. 5th and 7th Correct answer.
  4. 4th and 8th

Explanation

A six-pulse converter generates characteristic harmonics at orders equal to six times an integer plus or minus one, so the 5th, 7th, 11th, and 13th dominate. The 5th and 7th are usually the largest in magnitude. Even-order and triplen harmonics largely cancel in a balanced three-phase bridge.

Question 35Electrical Power Systems and Motors

An induction motor that is substantially oversized for its driven load will typically exhibit which operating characteristic?

  1. Higher power factor and lower efficiency
  2. Lower power factor and higher efficiency
  3. Lower power factor and lower efficiency Correct answer.
  4. Higher power factor and a higher efficiency

Explanation

At light load the magnetizing current becomes a large share of total current, so power factor falls sharply. Part-load efficiency also drops because fixed losses are spread over a smaller useful output. Matching motor size to actual load is therefore a standard efficiency measure.

Question 36Electrical Power Systems and Motors

At what loading does a transformer reach its maximum efficiency?

  1. When the load power factor is unity
  2. When core losses equal copper losses Correct answer.
  3. When copper losses are twice the core losses
  4. When the transformer carries full-load current

Explanation

Efficiency peaks where the constant core, or no-load, losses exactly equal the variable copper losses. Because copper loss grows with the square of load current, this balance typically occurs below nameplate rating. The load power factor affects how kVA converts to kW but not the loss-equality condition.

Question 37Electrical Power Systems and Motors

A 100 kW centrifugal pump runs 4,000 hours per year. A variable frequency drive reduces average flow to 80% of design. Using the affinity laws and ignoring drive losses, what is the approximate annual energy saving?

  1. About 100,000 kWh
  2. About 320,000 kWh
  3. About 80,000 kWh
  4. About 195,000 kWh Correct answer.

Explanation

For a centrifugal machine, shaft power varies with the cube of speed and flow. At 80% flow the power becomes 0.8 cubed, or about 0.512 of the original, a saving of roughly 48.8%. Applied to 100 kW for 4,000 hours, the saving is about 195,000 kWh per year.

Question 38Electrical Power Systems and Motors

Installing power factor correction capacitors in a facility with high harmonic distortion can create which problem?

  1. Parallel resonance that amplifies harmonic currents Correct answer.
  2. Harmonic distortion is reduced at the capacitor bank
  3. Lower harmonic levels because capacitors absorb them
  4. Higher motor synchronous speed and reduced slip

Explanation

The capacitor bank forms a resonant circuit with the source and transformer inductance, and the resonant frequency can coincide with a harmonic produced by drives. When that happens, harmonic voltages and currents are amplified, stressing capacitors and causing nuisance trips. Detuned reactors or tuned filter banks are used to shift the resonance safely.

Question 39Electrical Power Systems and Motors

A 50 hp (37 kW) motor with 94% nameplate efficiency draws a measured 30 kW at the input. What is its approximate load?

  1. About 60%
  2. About 81%
  3. About 76% Correct answer.
  4. About 94%

Explanation

Shaft output equals measured input power multiplied by motor efficiency, so 30 kW times 0.94 is about 28.2 kW. Dividing by the 37 kW rating gives roughly 76% load. Shaft output is always below the measured input because of motor losses.

Question 40Electrical Power Systems and Motors

A 300 kVAr capacitor bank is connected to a 480 V three-phase bus. What line current does the bank draw?

  1. 208 A
  2. 361 A Correct answer.
  3. 625 A
  4. 180 A

Explanation

Three-phase reactive power equals the square root of three times line voltage times line current, so current is kVAr divided by 1.732 times the line voltage. For 300 kVAr at 480 V, that is 300,000 divided by 831, or about 361 A. This is the same magnitude as the reactive current the bank supplies to the load.

Question 41Maintenance and Commissioning

Which of the following best describes the primary objective of a preventive maintenance program for building mechanical equipment?

  1. Repair of equipment only after a failure has occurred and a work order has been issued
  2. Scheduled service based on manufacturer guidance and operating history, before failure occurs Correct answer.
  3. Reduction of total maintenance labor by eliminating routine inspections and all scheduled service tasks
  4. Replacement of major equipment at fixed intervals regardless of its measured condition

Explanation

Preventive maintenance is planned, time- or usage-based service intended to reduce unplanned failures and preserve equipment efficiency. It is triggered by schedules and operating history rather than by breakdown. This keeps labor and downtime predictable and protects performance between capital renewals.

Question 42Maintenance and Commissioning

Vibration analysis performed on a large centrifugal fan motor is best classified as which type of maintenance activity?

  1. Deferred maintenance, postponed to a future budget cycle
  2. Predictive maintenance, based on measured condition data Correct answer.
  3. Routine housekeeping, performed by janitorial staff
  4. Corrective maintenance, performed after a deficiency is found

Explanation

Predictive or condition-based maintenance uses measured parameters such as vibration, temperature, and oil analysis to trend degradation and schedule intervention before functional failure. Corrective maintenance is the repair work done after a problem is identified. Vibration monitoring is a diagnostic input, not a repair task.

Question 43Maintenance and Commissioning

An infrared scan of an electrical panel shows one breaker termination running much hotter than the other two phases at comparable load. What is the most appropriate first action?

  1. De-energize the entire building immediately and replace the panel and all of its breakers
  2. Raise the load on the panel temporarily to confirm that the temperature reading repeats reliably
  3. Log the anomaly and check the termination; a phase delta under load signals added resistance Correct answer.
  4. Ignore the reading, since phase-to-phase temperature differences of this size are always normal

Explanation

Thermographic surveys compare phase-to-phase and similar-load conditions; an unbalanced temperature rise indicates a high-resistance connection such as a loose lug or deteriorated conductor. The finding is recorded, prioritized by severity, and the connection is investigated and repaired under a safe work plan. Load is not increased to verify a suspected hot connection.

Question 44Maintenance and Commissioning

A steam trap survey finds one trap discharging live steam continuously to the condensate return. What does this indicate and what action is required?

  1. The trap has failed open; repair or replace it, since live steam is being wasted Correct answer.
  2. The trap is undersized; a larger trap of the same type should be installed
  3. The trap is cold and blocked; it should be warmed slowly with live steam
  4. The trap is working normally; continuous discharge is expected on all steam traps

Explanation

A trap passing live steam to the return has failed in the open position, wasting the steam's latent heat and adding flash load to the condensate system. Trap surveys classify findings as blowing-through, cold or plugged, and leaking so repairs can be prioritized. Failed-open traps typically produce the largest energy penalty.

Question 45Maintenance and Commissioning

A plant compressor runs loaded most of the time, and a leak survey attributes a significant share of its output to leaks. Which approach best quantifies the value of repairing them?

  1. Compare the compressor nameplate horsepower with the plant electrical service rating
  2. Count the leaks found and multiply by the purchase price of a replacement fitting
  3. Convert saved airflow to input power using specific power, then to energy cost Correct answer.
  4. Measure the ambient temperature rise in the compressor room during loaded operation

Explanation

Leak savings are quantified by the reduction in delivered air flow, converted to compressor input power through the compressor's specific power in kW per cfm, then multiplied by operating hours and energy cost. This produces an annual dollar figure and simple payback for the repair program. Counting leaks yields no energy value.

Question 46Maintenance and Commissioning

In the commissioning process, the commissioning authority (CxA) is normally contracted by and reports to which party?

  1. The general contractor, so the CxA can direct the subcontractors' work
  2. The equipment manufacturer, so equipment warranties are protected
  3. The design engineer of record, so design issues can be resolved quickly
  4. The owner, so findings stay independent of the design and construction team Correct answer.

Explanation

The CxA serves the owner's interest, which requires independence from the organizations whose work is being verified. Independence lets the CxA report deficiencies candidly without commercial pressure from designers or builders. The CxA observes and documents contractor testing but does not direct construction means and methods.

Question 47Maintenance and Commissioning

The Owner's Project Requirements (OPR) developed at the start of a commissioning project primarily does which of the following?

  1. States the owner's measurable performance, occupancy and operating goals Correct answer.
  2. Serves as the contractor's means-and-methods plan for installing the systems
  3. Substitutes for the construction drawings and project specifications
  4. Serves as the contractor's schedule of pay applications and retainage

Explanation

The OPR documents what the owner needs the facility to do: measurable performance targets, occupancy schedules, redundancy, and operating constraints. Design and commissioning verification are then judged against those stated goals. It does not replace contract documents.

Question 48Maintenance and Commissioning

Functional performance testing of an air handling unit should demonstrate correct response under which set of conditions?

  1. Normal operation, staging, safeties, alarms and representative part loads Correct answer.
  2. Only with all VAV terminal boxes fully open and the fan at full speed
  3. Only at design full-load conditions with all terminal boxes at maximum
  4. Only with the building unoccupied and the controls in unoccupied mode

Explanation

Functional testing verifies interactive system behavior across its operating range, including staging transitions, safeties, alarms, and part-load sequences. Testing only at one condition leaves control logic unverified. Deferred or seasonal testing is used when a condition cannot be created at turnover.

Question 49Maintenance and Commissioning

An older office building has no reported operating problems, but the owner wants low-cost efficiency gains without major capital work. Which approach fits best?

  1. Commissioning of new construction against the contract documents
  2. Retro-commissioning, which tunes existing systems without major capital work Correct answer.
  3. Replacement of the entire HVAC system under a design-build contract
  4. A code-compliance review limited to envelope and lighting requirements

Explanation

Retro-commissioning applies a systematic investigation and tune-up process to existing systems and controls to restore performance toward intended design. It typically produces operational and energy savings at low cost. Major equipment replacement and new-construction commissioning address different situations.

Question 50Maintenance and Commissioning

Monitoring-based commissioning (MBCx) is characterized by which of the following?

  1. Ongoing analysis of trend data to detect faults Correct answer.
  2. Visual inspection of equipment nameplates and labels
  3. A single test performed only at project turnover
  4. Verification based only on monthly utility bills

Explanation

MBCx uses permanent metering and building automation trend data with analytics to detect performance faults continuously over time. It converts commissioning from a one-time event into a persistent process. Utility bills alone are too coarse and too delayed to locate faults.