Free CEM Test Energy Audits and Instrumentation Questions and Answers — Questions and Answers
Question 1: An energy auditor is conducting a preliminary assessment of a large industrial facility. The primary goal is to identify low-cost and no-cost energy saving opportunities and to determine if a more detailed audit is warranted. Which type of energy audit is most appropriate for this scenario?
- ASHRAE Level 2 Audit
- ASHRAE Level 3 Audit
- ASHRAE Level 1 Audit (Correct answer)
- Investment-Grade Audit
Correct answer: ASHRAE Level 1 Audit
An ASHRAE Level 1 audit, also known as a walk-through analysis, is the appropriate choice. It is designed to be a preliminary review to identify obvious areas of energy waste and to determine the potential for energy savings. This level of audit focuses on low-cost and no-cost measures and helps decide if a more detailed Level 2 or Level 3 audit is justified.
Question 2: During an energy audit of a compressed air system, an auditor detects a distinct high-frequency hissing sound near a pipe fitting, but the area is too noisy for the leak to be heard by ear. Which instrument would be most effective for pinpointing the exact location of this leak?
- Infrared Thermometer
- Anemometer
- Manometer
- Ultrasonic Leak Detector (Correct answer)
Correct answer: Ultrasonic Leak Detector
An ultrasonic leak detector is the ideal instrument for this task. Pressurized gas leaks create a high-frequency sound (ultrasound) that is beyond the range of human hearing. This instrument detects this ultrasonic noise and converts it into an audible signal, allowing the auditor to precisely locate the source of the leak even in a noisy industrial environment.
Question 3: A facility manager wants to proceed with a major HVAC system retrofit that involves significant capital investment. To secure financing, a highly detailed analysis with calibrated energy modeling, life-cycle cost analysis, and construction-grade cost estimates is required. Which of the following audits would provide the necessary level of detail?
- A Preliminary Walk-Through
- An ASHRAE Level 2 Audit
- An ASHRAE Level 3 Audit (Correct answer)
- A Utility Bill Analysis
Correct answer: An ASHRAE Level 3 Audit
An ASHRAE Level 3 audit, often called an "Investment-Grade Audit," is required for this situation. It provides a detailed engineering analysis of capital-intensive projects, often using whole-building computer simulations and extensive data logging to accurately model energy savings. This level of detail is necessary to support major financial decisions.
Question 4: An energy auditor is evaluating the efficiency of a natural gas-fired boiler. To determine the combustion efficiency, the auditor needs to analyze the composition of the flue gases. Which instrument is essential for this measurement?
- Combustion Analyzer (Correct answer)
- Infrared Camera
- Power Quality Analyzer
- Pitot Tube
Correct answer: Combustion Analyzer
A combustion analyzer is the correct instrument. It measures the content of flue gases, such as oxygen (O2), carbon monoxide (CO), and stack temperature, to determine the combustion efficiency of fuel-burning equipment like boilers and furnaces. This data allows the auditor to identify opportunities for improving efficiency and ensuring safe operation.
Question 5: To accurately measure the true power (kW) consumed by a three-phase motor, an energy auditor must measure which of the following sets of electrical parameters?
- Voltage and Current only
- Voltage, Current, and Resistance
- Voltage, Current, and Power Factor (Correct answer)
- Apparent Power (kVA) and Reactive Power (kVAR) only
Correct answer: Voltage, Current, and Power Factor
To determine the true power (kW) in an AC circuit, it is necessary to measure the voltage, current, and the power factor. The relationship is True Power (kW) = Voltage x Current x Power Factor (for a single-phase circuit, with an additional factor for three-phase). Measuring only voltage and current yields apparent power (kVA), not true power.
Question 6: Which of the following instruments is used to measure the quantity of light or illuminance level in a space, typically expressed in foot-candles or lux?
- Psychrometer
- Light Meter (Correct answer)
- Spectrometer
- Tachometer
Correct answer: Light Meter
A light meter, also known as a lux meter or photometer, is the instrument used to measure the intensity of visible light in a specific area. The measurements are commonly expressed in units of foot-candles (FC) or lux. This is crucial for verifying lighting levels meet design standards and identifying areas that are over-lit.
